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Pahlevan NM, Yao T, Chu K, Cole S, Tran T, Wood JC, King KS. Group delay method for MRI aortic pulse wave velocity measurements in clinical protocols with low temporal resolution: Validation in a heterogeneous cohort. Magn Reson Imaging 2020; 69:8-15. [PMID: 32105671 DOI: 10.1016/j.mri.2020.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/21/2020] [Accepted: 02/23/2020] [Indexed: 11/24/2022]
Abstract
BACKGROUND MRI assessment of aortic pulse wave velocity (PWV) helps predict the risk of vascular events, but the recommended phase contrast sampling rate is faster than what is utilized in most clinical sequences. There are many existing MRI databases obtained for assessment of cardiac output using lower temporal frequency sampling where information might be obtained about aortic stiffness (PWV). In this work, we sought to evaluate whether the Group Delay (GD) method can generate a reproducible measure of stiffness and describe expected age-related stiffening of the aortic arch using lower sampling rates in standard clinical sequences. METHODS Phase contrast (PC) MRI was obtained on the ascending and descending aortic arch in a heterogeneous adult cohort (n = 23; 9 women) spanning over a wide range of ages (ages 24-89, mean 49.4 ± 18.4). Data was collected with standard cardiac MRI protocols for cardiac output evaluation (repetition time = 7.8 ms, views-per-segment = 4, encoding velocity = 200 cm/s). Pulse wave transit times (TT) were computed using the GD method, two other validated automated approaches (cross correlation TT Algorithm by Gaddum and Segment by Medviso), and the manual tangent method. Pressure waveforms from tonometry and flow waveforms from PC MRI were used to assess wave reflections. RESULTS Group Delay and TT-Algorithm showed significant and high retest reproducibility (r = 0.86 for both) as well as high PWV correlation with age (r = 0.93, P-value < 0.00005 and r = 0.96, P-value < 0.00005 respectively) and with each other (r = 0.94, P-value < 0.00001, RMSE = 0.94 m/s). Arbitrary altering of the image acquisition trigger in the GD method introduced error of 10%-13%, but the TT-algorithm error range was 11%-25%. CONCLUSION Group Delay enables reproducible assessment of transit time to derive PWV from low temporal resolution clinical cardiac MRI sequences that can also identify age-related stiffening.
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Affiliation(s)
- Niema M Pahlevan
- Department of Aerospace & Mechanical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA; Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA 91105, USA.
| | - Timothy Yao
- Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA 91105, USA
| | - Karen Chu
- Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA 91105, USA.
| | - Soren Cole
- Department of Aerospace & Mechanical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA; Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA 91105, USA.
| | - Thao Tran
- Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA 91105, USA.
| | - John C Wood
- Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Division of Pediatric Cardiology, Children's Hospital Los Angeles, CA 90027, USA.
| | - Kevin S King
- Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA 91105, USA.
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Farrell AT, Panepinto J, Carroll CP, Darbari DS, Desai AA, King AA, Adams RJ, Barber TD, Brandow AM, DeBaun MR, Donahue MJ, Gupta K, Hankins JS, Kameka M, Kirkham FJ, Luksenburg H, Miller S, Oneal PA, Rees DC, Setse R, Sheehan VA, Strouse J, Stucky CL, Werner EM, Wood JC, Zempsky WT. End points for sickle cell disease clinical trials: patient-reported outcomes, pain, and the brain. Blood Adv 2019; 3:3982-4001. [PMID: 31809538 PMCID: PMC6963237 DOI: 10.1182/bloodadvances.2019000882] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/26/2019] [Indexed: 12/12/2022] Open
Abstract
To address the global burden of sickle cell disease (SCD) and the need for novel therapies, the American Society of Hematology partnered with the US Food and Drug Administration to engage the work of 7 panels of clinicians, investigators, and patients to develop consensus recommendations for clinical trial end points. The panels conducted their work through literature reviews, assessment of available evidence, and expert judgment focusing on end points related to: patient-reported outcomes (PROs), pain (non-PROs), the brain, end-organ considerations, biomarkers, measurement of cure, and low-resource settings. This article presents the findings and recommendations of the PROs, pain, and brain panels, as well as relevant findings and recommendations from the biomarkers panel. The panels identify end points, where there were supporting data, to use in clinical trials of SCD. In addition, the panels discuss where further research is needed to support the development and validation of additional clinical trial end points.
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Affiliation(s)
| | - Julie Panepinto
- Pediatric Hematology, Medical College of Wisconsin/Children's Wisconsin, Milwaukee, WI
| | - C Patrick Carroll
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD
| | | | - Ankit A Desai
- Krannert Institute of Cardiology, Indiana University, Bloomington, IN
| | - Allison A King
- Division of Hematology and Oncology in Pediatrics and Medicine, Washington University School of Medicine, St. Louis, MO
| | - Robert J Adams
- Department of Neurology, Medical University of South Carolina, Charleston, SC
| | | | - Amanda M Brandow
- Pediatric Hematology, Medical College of Wisconsin/Children's Wisconsin, Milwaukee, WI
| | - Michael R DeBaun
- Vanderbilt-Meharry Center of Excellence in Sickle Cell Disease, Vanderbilt University Medical Center, Nashville, TN
| | - Manus J Donahue
- Department of Radiology and Radiological Sciences
- Department of Neurology, and
- Department of Psychiatry, School of Medicine, Vanderbilt University, Nashville, TN
| | - Kalpna Gupta
- Division of Hematology, Oncology, and Transplantation, Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN
| | - Jane S Hankins
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN
| | - Michelle Kameka
- Nicole Wertheim College of Nursing and Health Sciences, Florida International University, Miami, FL
| | - Fenella J Kirkham
- Developmental Neurosciences Unit and
- Biomedical Research Unit, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Harvey Luksenburg
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | | | | | - David C Rees
- Department of Haematological Medicine, King's College Hospital, London, United Kingdom
- School of Cancer and Pharmaceutical Sciences, King's College London, London, United Kingdom
| | | | - Vivien A Sheehan
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - John Strouse
- Division of Hematology, Department of Medicine, and
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | - Cheryl L Stucky
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI
| | - Ellen M Werner
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - John C Wood
- Children's Hospital Los Angeles, Los Angeles, CA; and
| | - William T Zempsky
- Department of Pediatrics, Connecticut Children's/School of Medicine, University of Connecticut, Hartford, CT
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Cheng AL, Wee CP, Pahlevan NM, Wood JC. A 4D flow MRI evaluation of the impact of shear-dependent fluid viscosity on in vitro Fontan circulation flow. Am J Physiol Heart Circ Physiol 2019; 317:H1243-H1253. [PMID: 31585044 DOI: 10.1152/ajpheart.00296.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Fontan procedure for univentricular heart defects creates a nonphysiologic circulation where systemic venous blood drains directly into the pulmonary arteries, leading to multiorgan dysfunction secondary to chronic low-shear nonpulsatile pulmonary blood flow and central venous hypertension. Although blood viscosity increases exponentially in this low-shear environment, the role of shear-dependent ("non-Newtonian") blood viscosity in this pathophysiology is unclear. We studied three-dimensional (3D)-printed Fontan models in an in vitro flow loop with a Philips 3-T magnetic resonance imaging (MRI) scanner. A 4D flow phase-contrast sequence was used to acquire a time-varying 3D velocity field for each experimental condition. On the basis of blood viscosity of a cohort of patients who had undergone the Fontan procedure, it was decided to use 0.04% xanthan gum as a non-Newtonian blood analog; 45% glycerol was used as a Newtonian control fluid. MRI data were analyzed using GTFlow and MATLAB software. The primary outcome, power loss, was significantly higher with the Newtonian fluid [14.8 (13.3, 16.4) vs. 8.1 (6.4, 9.8)%, medians with 95% confidence interval, P < 0.0001]. The Newtonian fluid also demonstrated marginally higher right pulmonary artery flow, marginally lower shear stress, and a trend toward higher caval flow mixing. Outcomes were modulated by Fontan model complexity, cardiac output, and caval flow ratio. Vortexes, helical flow, and stagnant flow were more prevalent with the non-Newtonian fluid. Our data demonstrate that shear-dependent viscosity significantly alters qualitative flow patterns, power loss, pulmonary flow distribution, shear stress, and caval flow mixing in synthetic models of the Fontan circulation. Potential clinical implications include effects on exercise capacity, ventilation-perfusion matching, risk of pulmonary arteriovenous malformations, and risk of thromboembolism.NEW & NOTEWORTHY Although blood viscosity increases exponentially in low-shear environments, the role of shear-dependent ("non-Newtonian") blood viscosity in the pathophysiology of the low-shear Fontan circulation is unclear. We demonstrate that shear-dependent viscosity significantly alters qualitative flow patterns, power loss, pulmonary flow distribution, shear stress, and caval flow mixing in synthetic models of the Fontan circulation. Potential clinical implications include effects on exercise capacity, ventilation-perfusion matching, risk of pulmonary arteriovenous malformations, and risk of thromboembolism.
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Affiliation(s)
- Andrew L Cheng
- Division of Pediatric Cardiology, Children's Hospital Los Angeles, Los Angeles, California.,Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Choo Phei Wee
- Biostatistics Core, Children's Hospital Los Angeles, Los Angeles, California
| | - Niema M Pahlevan
- Keck School of Medicine, University of Southern California, Los Angeles, California.,Department of Aerospace and Mechanical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California
| | - John C Wood
- Division of Pediatric Cardiology, Children's Hospital Los Angeles, Los Angeles, California.,Keck School of Medicine, University of Southern California, Los Angeles, California
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Choi S, O'Neil SH, Joshi AA, Li J, Bush AM, Coates TD, Leahy RM, Wood JC. Anemia predicts lower white matter volume and cognitive performance in sickle and non-sickle cell anemia syndrome. Am J Hematol 2019; 94:1055-1065. [PMID: 31259431 DOI: 10.1002/ajh.25570] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 06/25/2019] [Accepted: 06/26/2019] [Indexed: 12/13/2022]
Abstract
Severe chronic anemia is an independent predictor of overt stroke, white matter damage, and cognitive dysfunction in the elderly. Severe anemia also predisposes to white matter strokes in young children, independent of the anemia subtype. We previously demonstrated symmetrically decreased white matter (WM) volumes in patients with sickle cell disease (SCD). In the current study, we investigated whether patients with non-sickle anemia also have lower WM volumes and cognitive dysfunction. Magnetic Resonance Imaging was performed on 52 clinically asymptomatic SCD patients (age = 21.4 ± 7.7; F = 27, M = 25; hemoglobin = 9.6 ± 1.6 g/dL), 26 non-sickle anemic patients (age = 23.9 ± 7.9; F = 14, M = 12; hemoglobin = 10.8 ± 2.5 g/dL) and 40 control subjects (age = 27.7 ± 11.3; F = 28, M = 12; hemoglobin = 13.4 ± 1.3 g/dL). Voxel-wise changes in WM brain volumes were compared to hemoglobin levels to identify brain regions that are vulnerable to anemia. White matter volume was diffusely lower in deep, watershed areas proportionally to anemia severity. After controlling for age, sex, and hemoglobin level, brain volumes were independent of disease. WM volume loss was associated with lower Full Scale Intelligence Quotient (FSIQ; P = .0048; r2 = .18) and an abnormal burden of silent cerebral infarctions (P = .029) in males, but not in females. Hemoglobin count and cognitive measures were similar between subjects with and without white-matter hyperintensities. The spatial distribution of volume loss suggests chronic hypoxic cerebrovascular injury, despite compensatory hyperemia. Neurocognitive consequences of WM volume changes and silent cerebral infarction were strongly sexually dimorphic. Understanding the possible neurological consequences of chronic anemia may help inform our current clinical practices.
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Affiliation(s)
- Soyoung Choi
- Neuroscience Graduate ProgramUniversity of Southern California Los Angeles California
- Signal and Image Processing InstituteUniversity of Southern California Los Angeles California
- Division of Hematology, Oncology and Blood and Marrow TransplantationChildren's Hospital Los Angeles Los Angeles California
| | - Sharon H. O'Neil
- The Saban Research Institute, Children's Hospital Los Angeles Los Angeles California
- Division of NeurologyChildren's Hospital Los Angeles Los Angeles California
- Department of Pediatrics, Keck School of MedicineUniversity of Southern California Los Angeles California
| | - Anand A. Joshi
- Signal and Image Processing InstituteUniversity of Southern California Los Angeles California
| | - Jian Li
- Signal and Image Processing InstituteUniversity of Southern California Los Angeles California
| | - Adam M. Bush
- Division of Hematology, Oncology and Blood and Marrow TransplantationChildren's Hospital Los Angeles Los Angeles California
- Biomedical EngineeringUniversity of Southern California Los Angeles California
- Radiology DepartmentStanford University Stanford California
| | - Thomas D. Coates
- Division of Hematology, Oncology and Blood and Marrow TransplantationChildren's Hospital Los Angeles Los Angeles California
- Department of Pediatrics, Keck School of MedicineUniversity of Southern California Los Angeles California
| | - Richard M. Leahy
- Neuroscience Graduate ProgramUniversity of Southern California Los Angeles California
- Signal and Image Processing InstituteUniversity of Southern California Los Angeles California
| | - John C. Wood
- Division of Hematology, Oncology and Blood and Marrow TransplantationChildren's Hospital Los Angeles Los Angeles California
- Department of Pediatrics, Keck School of MedicineUniversity of Southern California Los Angeles California
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Detterich JA, Liu H, Suriany S, Kato RM, Chalacheva P, Tedla B, Shah PM, Khoo MC, Wood JC, Coates TD, Milne GL, Oh JY, Patel RP, Forman HJ. Erythrocyte and plasma oxidative stress appears to be compensated in patients with sickle cell disease during a period of relative health, despite the presence of known oxidative agents. Free Radic Biol Med 2019; 141:408-415. [PMID: 31279092 PMCID: PMC6750280 DOI: 10.1016/j.freeradbiomed.2019.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/03/2019] [Accepted: 07/03/2019] [Indexed: 01/17/2023]
Abstract
Sickle cell disease (SCD) is a monogenetic disease that results in the formation of hemoglobin S. Due to more rapid oxidation of hemoglobin S due to intracellular heme and adventitious iron in SCD, it has been thought that an inherent property of SCD red cells would be an imbalance in antioxidant defenses and oxidant production. Less deformable and fragile RBC in SCD results in intravascular hemolysis and release of free hemoglobin (PFHb) in the plasma, which might be expected to produce oxidative stress in the plasma. Thus, we aimed to characterize intracellular and vascular oxidative stress in whole blood and plasma samples from adult SCD patients and controls recruited into a large study of SCD at Children's Hospital of Los Angeles. We evaluated the cellular content of metHb and several components of the antioxidant system in RBC as well as oxidation of GSH and Prx-2 oxidation in RBC after challenge with hydroperoxides. Plasma markers included PFHb, low molecular weight protein bound heme (freed heme), hemopexin, isoprostanes, and protein carbonyls. While GSH was slightly lower in SCD RBC, protein carbonyls, NADH, NAD+ and total NADP+ + NADPH were not different. Furthermore, GSH or Prx-2 oxidation was not different after oxidative challenge in SCD vs. Control. Elevated freed heme and PFHb had a significant negative, non-linear association with hemopexin. There appeared to be a threshold effect for hemopexin (200 μg/ml), under which the freed heme rose acutely. Plasma F2-isoprostanes were not significantly elevated in SCD. Despite significant release of Hb and elevation of freed heme in SCD when hemopexin was apparently saturated, there was no clear indication of uncompensated vascular oxidative stress. This somewhat surprising result, suggests that oxidative stress is well compensated in RBCs and plasma during a period of relative health.
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Affiliation(s)
- Jon A Detterich
- Division of Cardiology, Children's Hospital of Los Angeles, USA.
| | - Honglei Liu
- Division of Cardiology, Children's Hospital of Los Angeles, USA
| | - Silvie Suriany
- Division of Cardiology, Children's Hospital of Los Angeles, USA; Division of Hematology, Children's Hospital of Los Angeles, USA
| | | | | | - Bruke Tedla
- Division of Cardiology, Children's Hospital of Los Angeles, USA
| | - Payal M Shah
- Division of Hematology, Children's Hospital of Los Angeles, USA
| | - Michael C Khoo
- Viterbi School of Engineering, University of Southern California, USA
| | - John C Wood
- Division of Cardiology, Children's Hospital of Los Angeles, USA; Viterbi School of Engineering, University of Southern California, USA
| | - Thomas D Coates
- Division of Hematology, Children's Hospital of Los Angeles, USA
| | - Ginger L Milne
- Division of Clinical Pharmacology, Vanderbilt University, USA
| | - Joo-Yeun Oh
- Department of Pathology and Center for Free Radical Biology, University of Alabama School of Medicine, USA
| | - Rakesh P Patel
- Department of Pathology and Center for Free Radical Biology, University of Alabama School of Medicine, USA
| | - Henry Jay Forman
- Leonard Davis School of Gerontology, University of Southern California, USA
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Miao X, Nayak KS, Wood JC. In vivo validation of T2- and susceptibility-based S v O 2 measurements with jugular vein catheterization under hypoxia and hypercapnia. Magn Reson Med 2019; 82:2188-2198. [PMID: 31250481 DOI: 10.1002/mrm.27871] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/26/2019] [Accepted: 05/27/2019] [Indexed: 01/23/2023]
Abstract
PURPOSE To investigate the mutual agreement of T2-based and susceptibility-based methods as well as their agreement with jugular catheterization, for quantifying venous oxygen saturation (Sv O2 ) at a broad range of brain oxygenation levels. METHODS Sv O2 measurements using T2-relaxation-under-spin-tagging (TRUST) and susceptibility-based oximetry (SBO) were performed in 13 healthy subjects under room air, hypoxia, and hypercapnia conditions. Agreement between TRUST and SBO was quantitatively evaluated. In two of the subjects, TRUST and SBO were compared against the clinical gold standard, co-oximeter measurement via internal jugular vein catheterization. RESULTS Absolute Sv O2 measurements using TRUST and SBO were highly correlated across a range of saturations from 45% to 84% (Pearson r = 0.91, P < .0001). Sv O2 -TRUST was significantly lower than Sv O2 -SBO under hypoxia and room air conditions, but the two were comparable under hypercapnia. TRUST demonstrated a larger Sv O2 increase under hypercapnia than SBO and had good agreement with jugular catheterization under hypercapnia but significantly underestimated Sv O2 under room air and hypoxia. The agreement between Sv O2 -SBO and the reference did not depend on the physiological state. CONCLUSION A systematic bias was observed between T2-based and susceptibility-based methods that depended on the oxygenation state. In vivo validation with jugular catheterization indicated potential underestimation of TRUST under room air and hypoxia conditions. Our findings suggested that caution should be employed in comparison of absolute Sv O2 measurements using either TRUST or SBO.
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Affiliation(s)
- Xin Miao
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California
| | - Krishna S Nayak
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California.,Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California
| | - John C Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California.,Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California
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Detterich JA, Kato R, Bush A, Chalacheva P, Ponce D, De Zoysa M, Shah P, Khoo MC, Meiselman HJ, Coates TD, Wood JC. Sickle cell microvascular paradox-oxygen supply-demand mismatch. Am J Hematol 2019; 94:678-688. [PMID: 30916797 DOI: 10.1002/ajh.25476] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 12/13/2022]
Abstract
We have previously demonstrated that sickle cell disease (SCD) patients maintain normal global systemic and cerebral oxygen delivery by increasing cardiac output. However, ischemic end-organ injury remains common suggesting that tissue oxygen delivery may be impaired by microvascular dysregulation or damage. To test this hypothesis, we performed fingertip laser Doppler flowmetry measurements at the base of the nailbed and regional oxygen saturation (rSO2 ) on the dorsal surface of the same hand. This was done during flow mediated dilation (FMD) studies in 26 chronically transfused SCD, 75 non-transfused SCD, and 18 control subjects. Chronically transfused SCD patients were studied prior to and following a single transfusion and there was no acute change in rSO2 or perfusion. Laser Doppler estimates of resting perfusion were 76% higher in non-transfused and 110% higher in transfused SCD patients, compared to control subjects. In contrast, rSO2 was 12 saturation points lower in non-transfused SCD patients, but normal in the transfused SCD patients. During cuff occlusion, rSO2 declined at the same rate in all subjects suggesting similar intrinsic oxygen consumption rates. Upon cuff release, laser doppler post occlusive hyperemia was blunted in SCD patients in proportion to their resting perfusion values. Transfusion therapy did not improve the hyperemia response. FMD was impaired in SCD subjects but partially ameliorated in transfused SCD subjects. Taken together, non-transfused SCD subjects demonstrate impaired conduit artery FMD, impaired microcirculatory post-occlusive hyperemia, and resting hypoxia in the hand despite compensated oxygen delivery, suggesting impaired oxygen supply-demand matching. Transfusion improves FMD and oxygen supply-demand matching but not microcirculation hyperemic response.
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Affiliation(s)
- Jon A. Detterich
- Division of Cardiology, Children's Hospital Los AngelesUniversity of Southern California Keck School of Medicine Los Angeles California
- Department of Physiology and NeuroscienceUniversity of Southern California Keck School of Medicine Los Angeles California
| | - Roberta Kato
- Division of Pediatric PulmonologyChildren's Hospital Los Angeles Los Angeles California
| | - Adam Bush
- Department of Biomedical EngineeringUniversity of Southern California Viterbi School of Engineering
| | - Patjanaporn Chalacheva
- Department of Biomedical EngineeringUniversity of Southern California Viterbi School of Engineering
| | - Derek Ponce
- Division of Cardiology, Children's Hospital Los AngelesUniversity of Southern California Keck School of Medicine Los Angeles California
| | - Madushka De Zoysa
- Division of Cardiology, Children's Hospital Los AngelesUniversity of Southern California Keck School of Medicine Los Angeles California
| | - Payal Shah
- Division of Hematology Oncology, Children's Hospital Los AngelesUniversity of Southern California Keck School of Medicine Los Angeles California
| | - Michael C. Khoo
- Department of Biomedical EngineeringUniversity of Southern California Viterbi School of Engineering
| | - Herbert J. Meiselman
- Department of Physiology and NeuroscienceUniversity of Southern California Keck School of Medicine Los Angeles California
| | - Thomas D. Coates
- Division of Hematology Oncology, Children's Hospital Los AngelesUniversity of Southern California Keck School of Medicine Los Angeles California
| | - John C. Wood
- Division of Cardiology, Children's Hospital Los AngelesUniversity of Southern California Keck School of Medicine Los Angeles California
- Department of Biomedical EngineeringUniversity of Southern California Viterbi School of Engineering
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Shah P, Khaleel M, Thuptimdang W, Sunwoo J, Veluswamy S, Chalacheva P, Kato RM, Detterich J, Wood JC, Zeltzer L, Sposto R, Khoo MCK, Coates TD. Mental stress causes vasoconstriction in subjects with sickle cell disease and in normal controls. Haematologica 2019; 105:83-90. [PMID: 30975906 PMCID: PMC6939522 DOI: 10.3324/haematol.2018.211391] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/05/2019] [Indexed: 01/02/2023] Open
Abstract
Vaso-occlusive crisis (VOC) is a hallmark of sickle cell disease (SCD) and occurs when deoxygenated sickled red blood cells occlude the microvasculature. Any stimulus, such as mental stress, which decreases microvascular blood flow will increase the likelihood of red cell entrapment resulting in local vaso-occlusion and progression to VOC. Neurally mediated vasoconstriction might be the physiological link between crisis triggers and vaso-occlusion. In this study, we determined the effect of mental stress on microvascular blood flow and autonomic nervous system reactivity. Sickle cell patients and controls performed mentally stressful tasks, including a memory task, conflict test and pain anticipation test. Blood flow was measured using photoplethysmography, autonomic reactivity was derived from electrocardiography and perceived stress was measured by the State-Trait Anxiety Inventory questionnaire. Stress tasks induced a significant decrease in microvascular blood flow, parasympathetic withdrawal and sympathetic activation in all subjects. Of the various tests, pain anticipation caused the highest degree of vasoconstriction. The magnitude of vasoconstriction, sympathetic activation and perceived stress was greater during the Stroop conflict test than during the N-back memory test, indicating the relationship between magnitude of experimental stress and degree of regional vasoconstriction. Baseline anxiety had a significant effect on the vasoconstrictive response in sickle cell subjects but not in controls. In conclusion, mental stress caused vasoconstriction and autonomic nervous system reactivity in all subjects. Although the pattern of responses was not significantly different between the two groups, the consequences of vasoconstriction can be quite significant in SCD because of the resultant entrapment of sickle cells in the microvasculature. This suggests that mental stress can precipitate a VOC in SCD by causing neural-mediated vasoconstriction.
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Affiliation(s)
- Payal Shah
- Division of Hematology, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
| | - Maha Khaleel
- Division of Hematology, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
| | - Wanwara Thuptimdang
- Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles
| | - John Sunwoo
- Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles
| | - Saranya Veluswamy
- Division of Hematology, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
| | - Patjanaporn Chalacheva
- Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles
| | - Roberta M Kato
- Division of Pulmonology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
| | - Jon Detterich
- Division of Cardiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
| | - John C Wood
- Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles.,Division of Cardiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
| | - Lonnie Zeltzer
- Pediatric Pain Program, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
| | - Richard Sposto
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael C K Khoo
- Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles
| | - Thomas D Coates
- Division of Hematology, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles
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Chalacheva P, Kato RM, Shah P, Veluswamy S, Denton CC, Sunwoo J, Thuptimdang W, Wood JC, Detterich JA, Coates TD, Khoo MCK. Sickle Cell Disease Subjects Have a Distinct Abnormal Autonomic Phenotype Characterized by Peripheral Vasoconstriction With Blunted Cardiac Response to Head-Up Tilt. Front Physiol 2019; 10:381. [PMID: 31031633 PMCID: PMC6470196 DOI: 10.3389/fphys.2019.00381] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 03/19/2019] [Indexed: 12/26/2022] Open
Abstract
In sickle cell disease (SCD), prolonged capillary transit times, resulting from reduced peripheral blood flow, increase the likelihood of rigid red cells entrapment in the microvasculature, predisposing to vaso-occlusive crisis. Since changes in peripheral flow are mediated by the autonomic nervous system (ANS), we tested the hypothesis that the cardiac and peripheral vascular responses to head-up tilt (HUT) are abnormal in SCD. Heart rate, respiration, non-invasive continuous blood pressure and finger photoplethysmogram (PPG) were monitored before, during, and after HUT in SCD, anemic controls and healthy subjects. Percent increase in heart rate from baseline was used to quantify cardiac ANS response, while percent decrease in PPG amplitude represented degree of peripheral vasoconstriction. After employing cluster analysis to determine threshold levels, the HUT responses were classified into four phenotypes: (CP) increased heart rate and peripheral vasoconstriction; (C) increased heart rate only; (P) peripheral vasoconstriction only; and (ST) subthreshold cardiac and peripheral vascular responses. Multinomial logistic regression (MLR) was used to relate these phenotypic responses to various parameters representing blood properties and baseline cardiovascular activity. The most common phenotypic response, CP, was found in 82% of non-SCD subjects, including those with chronic anemia. In contrast, 70% of SCD subjects responded abnormally to HUT: C-phenotype = 22%, P-phenotype = 37%, or ST-phenotype = 11%. MLR revealed that the HUT phenotypes were significantly associated with baseline cardiac parasympathetic activity, baseline peripheral vascular variability, hemoglobin level and SCD diagnosis. Low parasympathetic activity at baseline dramatically increased the probability of belonging to the P-phenotype in SCD subjects, even after adjusting for hemoglobin level, suggesting a characteristic autonomic dysfunction that is independent of anemia. Further analysis using a mathematical model of heart rate variability revealed that the low parasympathetic activity in P-phenotype SCD subjects was due to impaired respiratory-cardiac coupling rather than reduced cardiac baroreflex sensitivity. By having strong peripheral vasoconstriction without compensatory cardiac responses, P-phenotype subjects may be at increased risk for vaso-occlusive crisis. The classification of autonomic phenotypes based on HUT response may have potential use for guiding therapeutic interventions to alleviate the risk of adverse outcomes in SCD.
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Affiliation(s)
- Patjanaporn Chalacheva
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - Roberta M Kato
- Divisions of Pulmonology, Children's Hospital Los Angeles, Los Angeles, CA, United States
| | - Payal Shah
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - Saranya Veluswamy
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - Christopher C Denton
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - John Sunwoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - Wanwara Thuptimdang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - John C Wood
- Divisions of Cardiology, Children's Hospital Los Angeles, Los Angeles, CA, United States
| | - Jon A Detterich
- Divisions of Cardiology, Children's Hospital Los Angeles, Los Angeles, CA, United States
| | - Thomas D Coates
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - Michael C K Khoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
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Chai Y, Bush AM, Coloigner J, Nederveen AJ, Tamrazi B, Vu C, Choi S, Coates TD, Lepore N, Wood JC. White matter has impaired resting oxygen delivery in sickle cell patients. Am J Hematol 2019; 94:467-474. [PMID: 30697803 PMCID: PMC6874897 DOI: 10.1002/ajh.25423] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/27/2018] [Accepted: 01/22/2019] [Indexed: 12/13/2022]
Abstract
Although modern medical management has lowered overt stroke occurrence in patients with sickle cell disease (SCD), progressive white matter (WM) damage remains common. It is known that cerebral blood flow (CBF) increases to compensate for anemia, but sufficiency of cerebral oxygen delivery, especially in the WM, has not been systematically investigated. Cerebral perfusion was measured by arterial spin labeling in 32 SCD patients (age range: 10-42 years old, 14 males, 7 with HbSC, 25 HbSS) and 25 age and race-matched healthy controls (age range: 15-45 years old, 10 males, 12 with HbAS, 13 HbAA); 8/24 SCD patients were receiving regular blood transfusions and 14/24 non-transfused SCD patients were taking hydroxyurea. Imaging data from control subjects were used to calculate maps for CBF and oxygen delivery in SCD patients and their T-score maps. Whole brain CBF was increased in SCD patients with a mean T-score of 0.5 and correlated with lactate dehydrogenase (r2 = 0.58, P < 0.0001). When corrected for oxygen content and arterial saturation, whole brain and gray matter (GM) oxygen delivery were normal in SCD, but WM oxygen delivery was 35% lower than in controls. Age and hematocrit were the strongest predictors for WM CBF and oxygen delivery in patients with SCD. There was spatial co-localization between regions of low oxygen delivery and WM hyperintensities on T2 FLAIR imaging. To conclude, oxygen delivery is preserved in the GM of SCD patients, but is decreased throughout the WM, particularly in areas prone to WM silent strokes.
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Affiliation(s)
- Yaqiong Chai
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
| | - Adam M. Bush
- Department of Radiology, Stanford, University, California
| | - Julie Coloigner
- Univ Rennes, CNRS, Inria, Inserm, IRISA UMR 6074, VISAGES - ERL U 1228, Rennes, France
| | - Aart J. Nederveen
- Department of Radiology and Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Benita Tamrazi
- Department of Radiology and Nuclear Medicine, Children’s Hospital Los Angeles,Los Angeles, California
| | - Chau Vu
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California
| | - Thomas D. Coates
- Section of Hematology, Children’s Hospital Los Angeles, Los Angeles, California
| | - Natasha Lepore
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
- Department of Radiology and Nuclear Medicine, Children’s Hospital Los Angeles,Los Angeles, California
| | - John C. Wood
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California
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62
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Hussein AE, Senabulya N, Ma Y, Streeter MJV, Kettle B, Dann SJD, Albert F, Bourgeois N, Cipiccia S, Cole JM, Finlay O, Gerstmayr E, González IG, Higginbotham A, Jaroszynski DA, Falk K, Krushelnick K, Lemos N, Lopes NC, Lumsdon C, Lundh O, Mangles SPD, Najmudin Z, Rajeev PP, Schlepütz CM, Shahzad M, Smid M, Spesyvtsev R, Symes DR, Vieux G, Willingale L, Wood JC, Shahani AJ, Thomas AGR. Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures. Sci Rep 2019; 9:3249. [PMID: 30824838 PMCID: PMC6397215 DOI: 10.1038/s41598-019-39845-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 01/29/2019] [Indexed: 12/19/2022] Open
Abstract
Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials can provide insight into their processing, structure, and performance. To demonstrate the imaging capability of X-rays from an LWFA we have examined an irregular eutectic in the aluminum-silicon (Al-Si) system. The lamellar spacing of the Al-Si eutectic microstructure is on the order of a few micrometers, thus requiring high spatial resolution. We present comparisons between the sharpness and spatial resolution in phase contrast images of this eutectic alloy obtained via X-ray phase contrast imaging at the Swiss Light Source (SLS) synchrotron and X-ray projection microscopy via an LWFA source. An upper bound on the resolving power of 2.7 ± 0.3 μm of the LWFA source in this experiment was measured. These results indicate that betatron X-rays from laser wakefield acceleration can provide an alternative to conventional synchrotron sources for high resolution imaging of eutectics and, more broadly, complex microstructures.
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Affiliation(s)
- A E Hussein
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109-2099, USA.
| | - N Senabulya
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109-2099, USA
| | - Y Ma
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109-2099, USA.,Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.,The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK
| | - M J V Streeter
- Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.,The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK.,The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | - B Kettle
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | - S J D Dann
- Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.,The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK
| | - F Albert
- Lawrence Livermore National Laboratory, NIF and Photon Sciences, Livermore, CA, 94550, USA
| | - N Bourgeois
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - S Cipiccia
- Diamond Light Source, Harwell Science and Innovation Campus, Fermi Avenue, Didcot, OX11 0DE, UK
| | - J M Cole
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | - O Finlay
- Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.,The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK
| | - E Gerstmayr
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | | | - A Higginbotham
- York Plasma Institute, Department of Physics, University of York, York, YO10 5DD, UK
| | - D A Jaroszynski
- The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK.,SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
| | - K Falk
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany.,Technische Universität Dresden, 01062, Dresden, Germany.,Institute of Physics of the ASCR, 182 21, Prague, Czech Republic
| | - K Krushelnick
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109-2099, USA
| | - N Lemos
- Lawrence Livermore National Laboratory, NIF and Photon Sciences, Livermore, CA, 94550, USA
| | - N C Lopes
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK.,GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, U.L., Lisboa, 1049-001, Portugal
| | - C Lumsdon
- York Plasma Institute, Department of Physics, University of York, York, YO10 5DD, UK
| | - O Lundh
- Department of Physics, Lund University, P.O. Box 118, S-22100, Lund, Sweden
| | - S P D Mangles
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | - Z Najmudin
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | - P P Rajeev
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - C M Schlepütz
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - M Shahzad
- The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK.,SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
| | - M Smid
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany.,ELI Beamlines, Institute of Physics of the ASCR, 182 21, Prague, Czech Republic
| | - R Spesyvtsev
- The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK.,SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
| | - D R Symes
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - G Vieux
- The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK.,SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
| | - L Willingale
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109-2099, USA
| | - J C Wood
- The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, UK
| | - A J Shahani
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109-2099, USA
| | - A G R Thomas
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109-2099, USA.,Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.,The Cockcroft Institute, Keckwick Lane, Daresbury, WA4 4AD, UK
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63
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Bhatt RR, Zeltzer LK, Coloigner J, Wood JC, Coates TD, Labus JS. Patients with sickle-cell disease exhibit greater functional connectivity and centrality in the locus coeruleus compared to anemic controls. Neuroimage Clin 2019; 21:101686. [PMID: 30690419 PMCID: PMC6356008 DOI: 10.1016/j.nicl.2019.101686] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 01/13/2019] [Accepted: 01/20/2019] [Indexed: 01/18/2023]
Abstract
Patients with sickle-cell disease (SCD) have greater resting-state functional connectivity between the locus coeruleus (LC) and dorsolateral prefrontal cortex (dlPFC). Patients with SCD have greater resting state centrality of the LC SCD patients with chronic pain exhibited even greater functional connectivity between the LC and dlPFC. This study supports hyper-connectivity between the LC and PFC is a potential chronic pain generator.
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Affiliation(s)
- Ravi R Bhatt
- UCLA Pediatric Pain and Palliative Care Program, Division of Hematology-Oncology, Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| | - Lonnie K Zeltzer
- UCLA Pediatric Pain and Palliative Care Program, Division of Hematology-Oncology, Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Julie Coloigner
- Childrens Hospital Los Angeles, Department of Radiology, Los Angeles, CA, USA; Childrens Hospital Los Angeles, Department of Cardiology, Los Angeles, CA, USA
| | - John C Wood
- Childrens Hospital Los Angeles, Department of Radiology, Los Angeles, CA, USA; Childrens Hospital Los Angeles, Department of Cardiology, Los Angeles, CA, USA
| | - Tom D Coates
- Childrens Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles (CCCBD), Los Angeles, CA, USA
| | - Jennifer S Labus
- Center for Neurobiology of Stress and Resilience, Department of Medicine, Vatche and Tamar Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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64
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Václavů L, Meynart BN, Mutsaerts HJMM, Petersen ET, Majoie CBLM, VanBavel ET, Wood JC, Nederveen AJ, Biemond BJ. Hemodynamic provocation with acetazolamide shows impaired cerebrovascular reserve in adults with sickle cell disease. Haematologica 2018; 104:690-699. [PMID: 30523051 PMCID: PMC6442969 DOI: 10.3324/haematol.2018.206094] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/23/2018] [Indexed: 01/26/2023] Open
Abstract
Sickle cell disease is characterized by chronic hemolytic anemia and vascular inflammation, which can diminish the vasodilatory capacity of the small resistance arteries, making them less adept at regulating cerebral blood flow. Autoregulation maintains adequate oxygen delivery, but when vasodilation is maximized, the low arterial oxygen content can lead to ischemia and silent cerebral infarcts. We used magnetic resonance imaging of cerebral blood flow to quantify whole-brain cerebrovascular reserve in 36 adult patients with sickle cell disease (mean age, 31.9±11.3 years) and 11 healthy controls (mean age, 37.4±15.4 years), and we used high-resolution 3D FLAIR magnetic resonance imaging to determine the prevalence of silent cerebral infarcts. Cerebrovascular reserve was calculated as the percentage change in cerebral blood flow after a hemodynamic challenge with acetazolamide. Co-registered lesion maps were used to demonstrate prevalent locations for silent cerebral infarcts. Cerebral blood flow was elevated in patients with sickle cell disease compared to controls (median [interquartile range]: 82.8 [20.1] vs. 51.3 [4.8] mL/100g/min, P<0.001). Cerebral blood flow was inversely associated with age, hemoglobin, and fetal hemoglobin, and correlated positively with bilirubin, and LDH, indicating that cerebral blood flow may reflect surrogates of hemolytic rate. Cerebrovascular reserve in sickle cell disease was decreased by half compared to controls (34.1 [33.4] vs. 69.5 [32.4] %, P<0.001) and was associated with hemoglobin and erythrocyte count indicating anemia-induced hemodynamic adaptations. In total, 29/36 patients (81%) and 5/11 controls (45%) had silent cerebral infarcts (median volume of 0.34 vs. 0.02 mL, P=0.03). Lesions were preferentially located in the borderzone. In conclusion, patients with sickle cell disease have a globally reduced cerebrovascular reserve as determined by arterial spin labeling with acetazolamide and reflects anemia–induced impaired vascular function in sickle cell disease. This study was registered at clinicaltrials.gov identifier 02824406.
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Affiliation(s)
- Lena Václavů
- Amsterdam UMC, Radiology and Nuclear Medicine, University of Amsterdam, the Netherlands
| | - Benoit N Meynart
- Amsterdam UMC, Radiology and Nuclear Medicine, University of Amsterdam, the Netherlands
| | - Henri J M M Mutsaerts
- Amsterdam UMC, Radiology and Nuclear Medicine, University of Amsterdam, the Netherlands
| | - Esben Thade Petersen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark
| | - Charles B L M Majoie
- Amsterdam UMC, Radiology and Nuclear Medicine, University of Amsterdam, the Netherlands
| | - Ed T VanBavel
- Amsterdam UMC, Biomedical Engineering and Physics, University of Amsterdam, the Netherlands
| | - John C Wood
- Cardiology and Radiology, Children's Hospital of Los Angeles, CA, USA
| | - Aart J Nederveen
- Amsterdam UMC, Radiology and Nuclear Medicine, University of Amsterdam, the Netherlands
| | - Bart J Biemond
- Amsterdam UMC, Hematology, Internal Medicine, University of Amsterdam, the Netherlands
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65
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Behm KT, Cole JM, Joglekar AS, Gerstmayr E, Wood JC, Baird CD, Blackburn TG, Duff M, Harvey C, Ilderton A, Kuschel S, Mangles SPD, Marklund M, McKenna P, Murphy CD, Najmudin Z, Poder K, Ridgers CP, Sarri G, Samarin GM, Symes D, Warwick J, Zepf M, Krushelnick K, Thomas AGR. A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV. Rev Sci Instrum 2018; 89:113303. [PMID: 30501337 DOI: 10.1063/1.5056248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/16/2018] [Indexed: 06/09/2023]
Abstract
We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.
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Affiliation(s)
- K T Behm
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA
| | - J M Cole
- The John Adams Institute for Accelerator Science, Imperial College London, London SW7 2AZ, United Kingdom
| | - A S Joglekar
- Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - E Gerstmayr
- The John Adams Institute for Accelerator Science, Imperial College London, London SW7 2AZ, United Kingdom
| | - J C Wood
- The John Adams Institute for Accelerator Science, Imperial College London, London SW7 2AZ, United Kingdom
| | - C D Baird
- York Plasma Institute, Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - T G Blackburn
- Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - M Duff
- SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - C Harvey
- Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - A Ilderton
- Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - S Kuschel
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, 07743 Jena, Germany
| | - S P D Mangles
- The John Adams Institute for Accelerator Science, Imperial College London, London SW7 2AZ, United Kingdom
| | - M Marklund
- Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - P McKenna
- SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - C D Murphy
- York Plasma Institute, Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - Z Najmudin
- The John Adams Institute for Accelerator Science, Imperial College London, London SW7 2AZ, United Kingdom
| | - K Poder
- The John Adams Institute for Accelerator Science, Imperial College London, London SW7 2AZ, United Kingdom
| | - C P Ridgers
- York Plasma Institute, Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - G Sarri
- School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom
| | - G M Samarin
- School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom
| | - D Symes
- Central Laser Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - J Warwick
- School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom
| | - M Zepf
- Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, 07743 Jena, Germany
| | - K Krushelnick
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA
| | - A G R Thomas
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA
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66
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Chai Y, Chen J, Galarza C, Sluman MA, Xu B, Vu CQ, Richard E, Mulder B, Tamrazi B, Lepore N, Mutsaerts HJMM, Wood JC. CEREBRAL BLOOD FLOW AND PREDICTORS OF WHITE MATTER LESIONS IN ADULTS WITH TETRALOGY OF FALLOT. Proc IEEE Int Symp Biomed Imaging 2018; 2018:1309-1312. [PMID: 30344894 DOI: 10.1109/isbi.2018.8363812] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Long-term outcomes for Tetralogy of Fallot (TOF) have improved dramatically in recent years, but survivors are still afflicted by cerebral damage. In this paper, we characterized the prevalence and predictors of cerebral silent infarction (SCI) and their relationship to cerebral blood flow (CBF) in 46 adult TOF patients. We calculated both whole brain and regional CBF using 2D arterial spin labeling (ASL) images, and investigated the spatial overlap between voxel-wise CBF values and white matter hyperintensities (WMHs) identified from T2-FLAIR images. SCIs were found in 83% of subjects and were predicted by the year of the patient's first cardiac surgery and patient's age at scanning (combined r2 0.44). CBF was not different in brain regions prone to stroke compared with healthy white matter.
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Affiliation(s)
- Yaqiong Chai
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles, CA, USA.,Department of Biomedical Engineering, University of Southern California, CA, USA.,Department of Radiology, Children's Hospital Los Angeles, CA, USA
| | - Jieshen Chen
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles, CA, USA.,Department of Electrical Engineering, University of Southern California, CA, USA
| | - Cristina Galarza
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles, CA, USA.,Keck School of Medicine, University of Southern California, CA, USA
| | - Maayke A Sluman
- Department of Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Botian Xu
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles, CA, USA.,Department of Electrical Engineering, University of Southern California, CA, USA
| | - Chau Q Vu
- Department of Biomedical Engineering, University of Southern California, CA, USA.,Department of Radiology, Children's Hospital Los Angeles, CA, USA
| | - Edo Richard
- Department of Neurology, Radboud University Medical Center, Amsterdam, The Netherlands
| | - Barbara Mulder
- Department of Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Benita Tamrazi
- Department of Radiology, Children's Hospital Los Angeles, CA, USA
| | - Natasha Lepore
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles, CA, USA.,Department of Biomedical Engineering, University of Southern California, CA, USA.,Department of Radiology, Children's Hospital Los Angeles, CA, USA
| | - Henri J M M Mutsaerts
- Sunnybrook Research Institute, University of Toronto, Toronto, Canada.,Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, CA, USA
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Miao X, Choi S, Tamrazi B, Chai Y, Vu C, Coates TD, Wood JC. Increased brain iron deposition in patients with sickle cell disease: an MRI quantitative susceptibility mapping study. Blood 2018; 132:1618-1621. [PMID: 30045839 PMCID: PMC6182265 DOI: 10.1182/blood-2018-04-840322] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Xin Miao
- Department of Biomedical Engineering and
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA; and
- Division of Cardiology
| | | | | | - Chau Vu
- Department of Biomedical Engineering and
| | - Thomas D Coates
- Hematology Section, Children's Center for Cancer, Blood Diseases and Bone Marrow Transplantation, Children's Hospital Los Angeles, Los Angeles, CA
| | - John C Wood
- Department of Biomedical Engineering and
- Division of Cardiology
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Sunwoo J, Chalacheva P, Khaleel M, Shah P, Sposto R, Kato RM, Detterich J, Zeltzer LK, Wood JC, Coates TD, Khoo MC. A novel cross-correlation methodology for assessing biophysical responses associated with pain. J Pain Res 2018; 11:2207-2219. [PMID: 30323655 PMCID: PMC6179586 DOI: 10.2147/jpr.s142582] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Purpose The purpose of this work was to noninvasively detect and quantify microvascular blood flow changes in response to externally applied pain in humans. The responsiveness of the microvasculature to pain stimulation might serve as an objective biomarker in diseases associated with altered pain perception and dysregulated vascular functions. The availability of such a biomarker may be useful as a tool for predicting outcome and response to treatments, particularly in diseases like sickle cell anemia where clinical manifestations are directly linked to microvascular perfusion. We, therefore, developed a method to distinguish the blood flow response due to the test stimulus from the blood flow measurement that also includes concurrent flow changes from unknown origins. Subjects and methods We measured the microvascular blood flow response in 24 healthy subjects in response to a train of randomly spaced and scaled heat pulses on the anterior forearm. The fingertip microvascular perfusion was measured using laser Doppler flowmetry. The cross-correlation between the heat pulses and the blood flow response was computed and tested for significance against the null distribution obtained from the baseline recording using bootstrapping method. Results We estimated correlation coefficients, response time, response significance, and the magnitude of vasoreactivity from microvascular blood flow responses. Based on these pain response indices, we identified strong responders and subjects who did not show significant responses. Conclusion The cross-correlation of a random pattern of painful stimuli with directly measured microvascular flow can detect vasoconstriction responses in a noisy blood flow signal, determine the time between stimulus and response, and quantify the magnitude of this response. This approach provided an objective measurement of vascular response to pain that may be an inherent characteristic of individual human subjects, and may also be related to the severity of vascular disorders.
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Affiliation(s)
- John Sunwoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA,
| | - Patjanaporn Chalacheva
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA,
| | - Maha Khaleel
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Payal Shah
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Richard Sposto
- Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Roberta M Kato
- Division of Pediatric Pulmonology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jon Detterich
- Division of Pediatric Cardiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Lonnie K Zeltzer
- Pediatric Pain and Palliative Care Program, Department of Pediatrics, Division of Hematology-Oncology, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, USA
| | - John C Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA, .,Division of Pediatric Cardiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Thomas D Coates
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael Ck Khoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA,
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Su JA, Kumar SR, Mahmoud H, Bowdish ME, Toubat O, Wood JC, Kung GC. Postoperative Serum Troponin Trends in Infants Undergoing Cardiac Surgery. Semin Thorac Cardiovasc Surg 2018; 31:244-251. [PMID: 30194978 DOI: 10.1053/j.semtcvs.2018.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/30/2018] [Indexed: 11/11/2022]
Abstract
Troponin-I (TN-I) levels are elevated following pediatric cardiac surgery with speculation that particular patterns may have prognostic significance. There is lack of procedure-specific data regarding postoperative TN-I levels in infants undergoing cardiac surgery. We hypothesized that TN-I elevation varies with type of surgery and persistent elevation predicts poor prognosis. We prospectively measured serial TN-I levels (preoperatively, 4, 8, 12, 24, and 48 hours postoperatively) in 90 infants (age < 1 year) undergoing cardiac surgery: off cardiopulmonary bypass (CPB) (n = 15), on CPB (n = 43), and on CPB with ventricular incision (CPB with ventricular incision; n = 32). All patients had undetectable baseline TN-I levels. The area under the curve of TN-I levels over the 48-hour period was significantly different among the surgical groups (P < 0.002), and highest in patients with CPB with ventricular incision. Generally, TN-I levels peaked by 4 hours after surgery and returned to near-normal levels within 48 hours. A persistent TN-I rise beyond 8 hours after surgery was a strong predictor of postoperative hypoperfusion injury (defined as a composite endpoint of end-organ injury resulting from inadequate perfusion, odds ratio 21.5; P = 0.001) and mortality (30% in those with persistently high TN-I, compared with 3.5% in the remaining patients; P < 0.001), independent of patient age, anatomy and/or complexity of surgery, and level of postoperative support. Our data provide benchmark values for TN-I levels following cardiac surgery in infants. Extent of TN-I elevation correlates with type of surgery. Persistent TN-I elevation beyond 8 hours after surgery is strongly associated with postoperative hypoperfusion injury and mortality.
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Affiliation(s)
- Jennifer A Su
- Division of Cardiology, University of Southern California, Los Angeles, California; Heart Institute, Children's Hospital of Los Angeles, Los Angeles, California.
| | - S Ram Kumar
- Heart Institute, Children's Hospital of Los Angeles, Los Angeles, California; Division of Cardiothoracic Surgery, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California; Department of Pediatrics, University of Southern California, Los Angeles, California
| | - Hesham Mahmoud
- Heart Institute, Children's Hospital of Los Angeles, Los Angeles, California
| | - Michael E Bowdish
- Division of Cardiothoracic Surgery, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Omar Toubat
- Heart Institute, Children's Hospital of Los Angeles, Los Angeles, California; Division of Cardiothoracic Surgery, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - John C Wood
- Division of Cardiology, University of Southern California, Los Angeles, California; Heart Institute, Children's Hospital of Los Angeles, Los Angeles, California; Department of Pediatrics, University of Southern California, Los Angeles, California
| | - Grace C Kung
- Division of Cardiology, University of Southern California, Los Angeles, California; Heart Institute, Children's Hospital of Los Angeles, Los Angeles, California; Department of Pediatrics, University of Southern California, Los Angeles, California
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70
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Bush AM, Coates TD, Wood JC. Diminished cerebral oxygen extraction and metabolic rate in sickle cell disease using T2 relaxation under spin tagging MRI. Magn Reson Med 2018; 80:294-303. [PMID: 29194727 PMCID: PMC5876140 DOI: 10.1002/mrm.27015] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/26/2017] [Accepted: 10/26/2017] [Indexed: 11/09/2022]
Abstract
PURPOSE T2 MRI oximetry can noninvasively determine oxygen saturation (Y) but requires empirical MR calibration models to convert the measured blood transverse relaxation (T2b ) into Y. The accuracy of existing T2b models in the presence of blood disorders such as sickle cell disease (SCD) remains unknown. METHODS A Carr Purcell Meiboom Gill T2 preparation sequence was used to make 83 whole blood measurements from 11 subjects with SCD to derive an ex vivo sickle hemoglobin (HbS) T2b model. Forearm venous blood gas, sagittal sinus T2 (T2 Relaxation Under Spin Tagging) and total brain blood flow (phase contrast MRI) were measured in 37 healthy controls and 33 SCD subjects (age 24.6 ± 10.2 years). Cerebral oxygen saturation, extraction fraction, and metabolic rate estimates were calculated using three separate T2b models. Cerebral and forearm oxygen extraction fraction were compared. RESULTS Ex vivo, SCD blood had greater saturation dependent relaxivity than control blood, with a weak dependence on HbS and no dependence on hematocrit. In vivo, the HbS T2b model predicted Yv values with lowest coefficient of variation (compared with existing T2b models) and the strongest correlation with peripheral venous oximetry (r2 = .29). The HbS T2b model predicted systematically higher Yv measurements in SCD patients (73 ± 5 and 61 ± 6; P < 0.0001) which was mirrored by peripheral venous measurements (75 ± 20 and 45 ± 20; P < 0.0001). CONCLUSION Cerebral and peripheral oxygen extraction are decreased in SCD patients, suggesting either blood flow is increased beyond metabolic demands or the presence of physiological arterial-venous shunting. Magn Reson Med 80:294-303, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Adam M Bush
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Thomas D Coates
- Division of Hematology/Oncology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
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71
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Coloigner J, Phlypo R, Coates TD, Lepore N, Wood JC. Graph Lasso-Based Test for Evaluating Functional Brain Connectivity in Sickle Cell Disease. Brain Connect 2018; 7:443-453. [PMID: 28747064 DOI: 10.1089/brain.2016.0474] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Sickle cell disease (SCD) is a vascular disorder that is often associated with recurrent ischemia-reperfusion injury, anemia, vasculopathy, and strokes. These cerebral injuries are associated with neurological dysfunction, limiting the full developing potential of the patient. However, recent large studies of SCD have demonstrated that cognitive impairment occurs even in the absence of brain abnormalities on conventional magnetic resonance imaging (MRI). These observations support an emerging consensus that brain injury in SCD is diffuse and that conventional neuroimaging often underestimates the extent of injury. In this article, we postulated that alterations in the cerebral connectivity may constitute a sensitive biomarker of SCD severity. Using functional MRI, a connectivity study analyzing the SCD patients individually was performed. First, a robust learning scheme based on graphical lasso model and Fréchet mean was used for estimating a consistent descriptor of healthy brain connectivity. Then, we tested a statistical method that provides an individual index of similarity between this healthy connectivity model and each SCD patient's connectivity matrix. Our results demonstrated that the reference connectivity model was not appropriate to model connectivity for only 4 out of 27 patients. After controlling for the gender, two separate predictors of this individual similarity index were the anemia (p = 0.02) and white matter hyperintensities (WMH) (silent stroke) (p = 0.03), so that patients with low hemoglobin level or with WMH have the least similarity to the reference connectivity model. Further studies are required to determine whether the resting-state connectivity changes reflect pathological changes or compensatory responses to chronic anemia.
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Affiliation(s)
- Julie Coloigner
- 1 CIBORG, Division of Radiology, Children's Hospital Los Angeles , Los Angeles, California
| | - Ronald Phlypo
- 2 University of Grenoble Alpes , CNRS, Grenoble INP, GIPSA-Lab, Grenoble, France
| | - Thomas D Coates
- 3 Division of Hematology, Children's Hospital Los Angeles , Los Angeles, California
| | - Natasha Lepore
- 1 CIBORG, Division of Radiology, Children's Hospital Los Angeles , Los Angeles, California
| | - John C Wood
- 4 Division of Cardiology, Children's Hospital Los Angeles , Los Angeles, California
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72
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Xu B, Chai Y, Galarza CM, Vu CQ, Tamrazi B, Gaonkar B, Macyszyn L, Coates TD, Lepore N, Wood JC. ORCHESTRAL FULLY CONVOLUTIONAL NETWORKS FOR SMALL LESION SEGMENTATION IN BRAIN MRI. Proc IEEE Int Symp Biomed Imaging 2018; 2018:889-892. [PMID: 30344893 PMCID: PMC6192017 DOI: 10.1109/isbi.2018.8363714] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
White matter (WM) lesion identification and segmentation has proved of clinical importance for diagnosis, treatment and neurological outcomes. Convolutional neural networks (CNN) have demonstrated their success for large lesion load segmentation, but are not sensitive to small deep WM and sub-cortical lesion segmentation. We propose to use multi-scale and supervised fully convolutional networks (FCN) to segment small WM lesions in 22 anemic patients. The multiple scales enable us to identify the small lesions while reducing many false alarms, and the multi-supervised scheme allows a better management of the unbalanced data. Compared to a single FCN (Dice score ~0.31), the performance on the testing dataset of our proposed networks achieved a Dice score of 0.78.
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Affiliation(s)
- Botian Xu
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles (CHLA)
- Department of Electrical Engineering, USC
| | - Yaqiong Chai
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles (CHLA)
- Department of Biomedical Engineering, University of Southern California (USC)
- Department of Radiology, CHLA
| | - Cristina M Galarza
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles (CHLA)
- Keck School of Medicine, USC
| | - Chau Q Vu
- Department of Biomedical Engineering, University of Southern California (USC)
- Department of Radiology, CHLA
| | | | - Bilwaj Gaonkar
- Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles
| | - Luke Macyszyn
- Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles
| | | | - Natasha Lepore
- CIBORG laboratory, Department of Radiology, Children's Hospital Los Angeles (CHLA)
- Department of Biomedical Engineering, University of Southern California (USC)
- Department of Radiology, CHLA
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73
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Cheng AL, Pahlevan NM, Rinderknecht DG, Wood JC, Gharib M. Experimental Investigation of the Effect of Non-Newtonian Behavior of Blood Flow in the Fontan Circulation. Eur J Mech B Fluids 2018; 68:184-192. [PMID: 29736127 PMCID: PMC5935448 DOI: 10.1016/j.euromechflu.2017.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The Fontan procedure for univentricular heart defects creates a unique circulation where all pulmonary blood flow is passively supplied directly from systemic veins. Computational simulations, aimed at optimizing the surgery, have assumed blood to be a Newtonian fluid without evaluating the potential error introduced by this assumption. We compared flow behavior between a non-Newtonian blood analog (0.04% xanthan gum) and a control Newtonian fluid (45% glycerol) in a simplified model of the Fontan circulation. Particle image velocimetry was used to examine flow behavior at two different cardiac outputs and two caval blood flow distributions. Pressure and flow rates were measured at each inlet and outlet. Velocity, shear strain, and shear stress maps were derived from velocity data. Power loss was calculated from pressure, flow, and velocity data. Power loss was increased in all test conditions with xanthan gum vs. glycerol (mean 10±2.9% vs. 5.6±1.3%, p=0.032). Pulmonary blood flow distribution differed in all conditions, more so at low cardiac output. Caval blood flow mixing patterns and shear stress were also qualitatively different between the solutions in all conditions. We conclude that assuming blood to be a Newtonian fluid introduces considerable error into simulations of the Fontan circulation, where low-shear flow predominates.
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Affiliation(s)
- Andrew L. Cheng
- Division of Pediatric Cardiology, Department of Pediatrics, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Niema M. Pahlevan
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, USA
- Huntington Medical Research Institutes, Pasadena, CA, USA
| | - Derek G. Rinderknecht
- Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, CA, USA
| | - John C. Wood
- Division of Pediatric Cardiology, Department of Pediatrics, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Morteza Gharib
- Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, CA, USA
- Department of Medical Engineering, California Institute of Technology, Pasadena, CA, USA
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74
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Wish JB, Aronoff GR, Bacon BR, Brugnara C, Eckardt KU, Ganz T, Macdougall IC, Núñez J, Perahia AJ, Wood JC. Positive Iron Balance in Chronic Kidney Disease: How Much is Too Much and How to Tell? Am J Nephrol 2018; 47:72-83. [PMID: 29439253 DOI: 10.1159/000486968] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 01/15/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Regulation of body iron occurs at cellular, tissue, and systemic levels. In healthy individuals, iron absorption and losses are minimal, creating a virtually closed system. In the setting of chronic kidney disease and hemodialysis (HD), increased iron losses, reduced iron absorption, and limited iron availability lead to iron deficiency. Intravenous (IV) iron therapy is frequently prescribed to replace lost iron, but determining an individual's iron balance and stores can be challenging and imprecise, contributing to uncertainty about the long-term safety of IV iron therapy. SUMMARY Patients on HD receiving judicious doses of IV iron are likely to be in a state of positive iron balance, yet this does not appear to confer an overt risk for clinically relevant iron toxicity. The concomitant use of iron with erythropoiesis-stimulating agents, the use of maintenance iron dosing regimens, and the reticuloendothelial distribution of hepatic iron deposition likely minimize the potential for iron toxicity in patients on HD. Key Messages: Because no single diagnostic test can, at present, accurately assess iron status and risk for toxicity, clinicians need to take an integrative approach to avoid iron doses that impose excessive exposure while ensuring sufficient replenishment of iron stores capable of overcoming hepcidin blockade and allowing for effective erythropoiesis.
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Affiliation(s)
- Jay B Wish
- Division of Nephrology, Indiana University Health, Indianapolis, Indiana, USA
| | - George R Aronoff
- Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky, USA
- DaVita Kidney Care, Denver, Colorado, USA
| | - Bruce R Bacon
- Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Carlo Brugnara
- Department of Laboratory Medicine, Boston Children's Hospital and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA
| | - Kai-Uwe Eckardt
- Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin, Berlin, Germany
| | - Tomas Ganz
- Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA
| | - Iain C Macdougall
- Department of Renal Medicine, King's College Hospital, Denmark Hill, London, United Kingdom
| | - Julio Núñez
- Cardiology Service, Hospital Clínico Universitario, INCLIVA, CIBERCV and University of Valencia, Valencia, Spain
| | - Adam J Perahia
- NorthStar Strategic Consulting, LLC, Gladstone, New Jersey, USA
| | - John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
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75
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Václavů L, Baldew ZAV, Gevers S, Mutsaerts HJMM, Fijnvandraat K, Cnossen MH, Majoie CB, Wood JC, VanBavel E, Biemond BJ, van Ooij P, Nederveen AJ. Intracranial 4D flow magnetic resonance imaging reveals altered haemodynamics in sickle cell disease. Br J Haematol 2017; 180:432-442. [PMID: 29270975 DOI: 10.1111/bjh.15043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 09/30/2017] [Indexed: 11/28/2022]
Abstract
Stroke risk in children with sickle cell disease (SCD) is currently assessed with routine transcranial Doppler ultrasound (TCD) measurements of blood velocity in the Circle of Willis (CoW). However, there is currently no biomarker with proven prognostic value in adult patients. Four-dimensional (4D) flow magnetic resonance imaging (MRI) may improve risk profiling based on intracranial haemodynamics. We conducted neurovascular 4D flow MRI and blood sampling in 69 SCD patients [median age 15 years (interquartile range, IQR: 12-50)] and 14 healthy controls [median age 21 years (IQR: 18-43)]. We measured velocity, flow, lumen area and endothelial shear stress (ESS) in the CoW. SCD patients had lower haematocrit and viscosity, and higher velocity, flow and lumen area, with lower ESS compared to healthy controls. We observed significant age-related decline in haemodynamic 4D flow parameters; velocity (Spearman's ρ = -0·36 to -0·61), flow (ρ = -0·26 to -0·52) and ESS (ρ = -0·14 to -0·54) in SCD patients. Further analysis in only adults showed that velocity values were similar in SCD patients compared to healthy controls, but that the additional 4D flow parameters, flow and lumen area, were higher, and ESS lower, in the SCD group. Our data suggest that 4D flow MRI may identify adult patients with an increased stroke risk more accurately than current TCD-based velocity.
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Affiliation(s)
- Lena Václavů
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Zelonna A V Baldew
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Sanna Gevers
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Henri J M M Mutsaerts
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Karin Fijnvandraat
- Paediatric Haematology, Emma Children's Hospital, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Marjon H Cnossen
- Paediatric Haematology, Erasmus University Hospital-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Charles B Majoie
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - John C Wood
- Paediatric Cardiology, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Ed VanBavel
- Biomedical Engineering and Physics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Bart J Biemond
- Haematology, Internal Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Pim van Ooij
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Aart J Nederveen
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Khaleel M, Puliyel M, Shah P, Sunwoo J, Kato RM, Chalacheva P, Thuptimdang W, Detterich J, Wood JC, Tsao J, Zeltzer L, Sposto R, Khoo MCK, Coates TD. Individuals with sickle cell disease have a significantly greater vasoconstriction response to thermal pain than controls and have significant vasoconstriction in response to anticipation of pain. Am J Hematol 2017; 92:1137-1145. [PMID: 28707371 DOI: 10.1002/ajh.24858] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 07/07/2017] [Accepted: 07/10/2017] [Indexed: 12/17/2022]
Abstract
The painful vaso-occlusive crises (VOC) that characterize sickle cell disease (SCD) progress over hours from the asymptomatic steady-state. SCD patients report that VOC can be triggered by stress, cold exposure, and, pain itself. We anticipated that pain could cause neural-mediated vasoconstriction, decreasing regional blood flow and promoting entrapment of sickle cells in the microvasculature. Therefore, we measured microvascular blood flow in the fingers of both hands using plethysmography and laser-Doppler flowmetry while applying a series of painful thermal stimuli on the right forearm in 23 SCD patients and 25 controls. Heat pain applied to one arm caused bilateral decrease in microvascular perfusion. The vasoconstriction response started before administration of the thermal pain stimulus in all subjects, suggesting that pain anticipation also causes significant vasoconstriction. The time delay between thermal pain application and global vasoconstriction ranged from 5 to 15.5 seconds and increased with age (P < .01). Although subjective measures, pain threshold and pain tolerance were not different between SCD subjects and controls, but the vaso-reactivity index characterizing the microvascular blood flow response to painful stimuli was significantly higher in SCD patients (P = .0028). This global vasoconstriction increases microvascular transit time, and may promote entrapment of sickle cells in the microvasculature, making vaso-occlusion more likely. The rapidity of the global vasoconstriction response indicates a neural origin that may play a part in the transition from steady-state to VOC, and may also contribute to the variability in VOC frequency observed in SCD patients.
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Affiliation(s)
- Maha Khaleel
- Section of Hematology; Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
| | - Mammen Puliyel
- Section of Hematology; Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
| | - Payal Shah
- Section of Hematology; Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
| | - John Sunwoo
- Biomedical engineering; Viterbi School of Engineering; Los Angeles California
| | - Roberta M. Kato
- Division of Pulmonology; Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
| | | | - Wanwara Thuptimdang
- Biomedical engineering; Viterbi School of Engineering; Los Angeles California
| | - Jon Detterich
- Division of Cardiology; Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
| | - John C. Wood
- Biomedical engineering; Viterbi School of Engineering; Los Angeles California
- Division of Cardiology; Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
| | - Jennie Tsao
- Pediatric Pain Program, University of California Los Angeles; Los Angeles California
| | - Lonnie Zeltzer
- Pediatric Pain Program, University of California Los Angeles; Los Angeles California
| | - Richard Sposto
- Section of Hematology; Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
- Department of Preventive Medicine, Keck School of Medicine; University of Southern California; Los Angeles California
| | - Michael C. K. Khoo
- Biomedical engineering; Viterbi School of Engineering; Los Angeles California
| | - Thomas D. Coates
- Section of Hematology; Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Keck School of Medicine; Los Angeles California
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Coloigner J, Kim Y, Bush A, Choi S, Balderrama MC, Coates TD, O’Neil SH, Lepore N, Wood JC. Contrasting resting-state fMRI abnormalities from sickle and non-sickle anemia. PLoS One 2017; 12:e0184860. [PMID: 28981541 PMCID: PMC5628803 DOI: 10.1371/journal.pone.0184860] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 08/31/2017] [Indexed: 11/20/2022] Open
Abstract
Sickle cell disease (SCD) is a chronic blood disorder that is often associated with acute and chronic cerebrovascular complications, including strokes and impaired cognition. Using functional resting state magnetic resonance images, we performed whole-brain analysis of the amplitude of low frequency fluctuations (ALFF), to detect areas of spontaneous blood oxygenation level dependent signal across brain regions. We compared the ALFF of 20 SCD patients to that observed in 19 healthy, age and ethnicity-matched, control subjects. Significant differences were found in several brain regions, including the insula, precuneus, anterior cingulate cortex and medial superior frontal gyrus. To identify the ALFF differences resulting from anemia alone, we also compared the ALFF of SCD patients to that observed in 12 patients having comparable hemoglobin levels but lacking sickle hemoglobin. Increased ALFF in the orbitofrontal cortex and the anterior and posterior cingulate cortex and decreased ALFF in the frontal pole, cerebellum and medial superior frontal gyrus persisted after accounting for the effect of anemia. The presence of white matter hyperintensities was associated with depressed frontal and medial superior frontal gyri activity in the SCD subjects. Decreased ALFF in the frontal lobe was correlated with decreased verbal fluency and cognitive flexibility. These findings may lead to a better understanding of the pathophysiology of SCD.
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Affiliation(s)
- Julie Coloigner
- CIBORG laboratory, Division of Radiology, Children’s Hospital, Los Angeles, California, United States of America
| | - Yeun Kim
- CIBORG laboratory, Division of Radiology, Children’s Hospital, Los Angeles, California, United States of America
| | - Adam Bush
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, United States of America
| | - Melissa C. Balderrama
- Division of Hematology, Oncology and Blood and Marrow Transplantation, Children’s Hospital, Los Angeles, California, United States of America
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Thomas D. Coates
- Division of Hematology, Oncology and Blood and Marrow Transplantation, Children’s Hospital, Los Angeles, California, United States of America
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Sharon H. O’Neil
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Division of Neurology, Children’s Hospital, Los Angeles, California, United States of America
- The Saban Research Institute, Children’s Hospital, Los Angeles, California, United States of America
| | - Natasha Lepore
- CIBORG laboratory, Division of Radiology, Children’s Hospital, Los Angeles, California, United States of America
| | - John C. Wood
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Division of Cardiology, Children’s Hospital, Los Angeles, California, United States of America
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Affiliation(s)
- John C Wood
- Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles-USC Keck School of Medicine, Los Angeles, CA, United States
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Borzage M, Heidari K, Chavez T, Seri I, Wood JC, Blüml S. Measuring Stroke Volume: Impedance Cardiography vs Phase-Contrast Magnetic Resonance Imaging. Am J Crit Care 2017; 26:408-415. [PMID: 28864438 DOI: 10.4037/ajcc2017488] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
BACKGROUND Determination of cardiac output requires measurement of both heart rate and stroke volume. Techniques for measuring heart rate are widespread, and 1 technique for bedside monitoring of stroke volume is electrical impedance cardiography. OBJECTIVES To determine the accuracy and precision of stroke volume measured via impedance cardiography and whether the technique can be used to detect trends. METHODS Eleven healthy research participants (22-52 years old) were examined with simultaneous impedance cardiography and phase-contrast magnetic resonance imaging at rest and during exercise. Bland-Altman analysis with repeated-measures correction was used to compare stroke volumes determined with the 2 methods. The suitability of impedance cardiography for detecting trends in stroke volume was analyzed by using the Critchley radial limits of agreement method. RESULTS Phase-contrast magnetic resonance imaging indicated a mean stroke volume of 87 (SD, 16) mL at rest; in 9 volunteers, it changed during exercise (P = .04 to P < .001); in 2 volunteers, it did not (P = .32, P = .06). For the range of stroke-volume measurements (60-122 mL), impedance cardiography yielded underestimates of stroke volumes at the low end (bias, -17 mL) and overestimates at the high end (bias, +17 mL; P < .001). Corresponding 95% limits of agreement were 64 mL, a 73% overestimate or underestimate of stroke volume at rest. Critchley radial limits of agreement indicated poor concordance of stroke-volume trends. CONCLUSIONS Impedance cardiography had low accuracy and precision in measuring absolute stroke volume and was a poor detector of stroke-volume trends.
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Affiliation(s)
- Matthew Borzage
- Matthew Borzage is an assistant professor of research, Division of Neonatology and Department of Radiology, Children's Hospital Los Angeles, and the Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California. Kimia Heidari is a clinical research coordinator and Thomas Chavez is a statistician and clinical research coordinator, Division of Neonatology, Children's Hospital Los Angeles, and Department of Pediatrics, Keck School of Medicine, University of Southern California. Istvan Seri is a professor of pediatrics, Weill Cornell Medical College, New York, New York; director, Sidra Neonatology Center of Excellence, Sidra Medical and Research Center, Doha, Qatar; and adjunct professor of pediatrics, Keck School of Medicine, University of Southern California. John C. Wood is a professor, Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles and Department of Biomedical Engineering, University of Southern California. Stefan Blüml is an associate professor of research radiology and biomedical engineering, Keck School of Medicine and Department of Biomedical Engineering, University of Southern California.
| | - Kimia Heidari
- Matthew Borzage is an assistant professor of research, Division of Neonatology and Department of Radiology, Children's Hospital Los Angeles, and the Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California. Kimia Heidari is a clinical research coordinator and Thomas Chavez is a statistician and clinical research coordinator, Division of Neonatology, Children's Hospital Los Angeles, and Department of Pediatrics, Keck School of Medicine, University of Southern California. Istvan Seri is a professor of pediatrics, Weill Cornell Medical College, New York, New York; director, Sidra Neonatology Center of Excellence, Sidra Medical and Research Center, Doha, Qatar; and adjunct professor of pediatrics, Keck School of Medicine, University of Southern California. John C. Wood is a professor, Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles and Department of Biomedical Engineering, University of Southern California. Stefan Blüml is an associate professor of research radiology and biomedical engineering, Keck School of Medicine and Department of Biomedical Engineering, University of Southern California
| | - Thomas Chavez
- Matthew Borzage is an assistant professor of research, Division of Neonatology and Department of Radiology, Children's Hospital Los Angeles, and the Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California. Kimia Heidari is a clinical research coordinator and Thomas Chavez is a statistician and clinical research coordinator, Division of Neonatology, Children's Hospital Los Angeles, and Department of Pediatrics, Keck School of Medicine, University of Southern California. Istvan Seri is a professor of pediatrics, Weill Cornell Medical College, New York, New York; director, Sidra Neonatology Center of Excellence, Sidra Medical and Research Center, Doha, Qatar; and adjunct professor of pediatrics, Keck School of Medicine, University of Southern California. John C. Wood is a professor, Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles and Department of Biomedical Engineering, University of Southern California. Stefan Blüml is an associate professor of research radiology and biomedical engineering, Keck School of Medicine and Department of Biomedical Engineering, University of Southern California
| | - Istvan Seri
- Matthew Borzage is an assistant professor of research, Division of Neonatology and Department of Radiology, Children's Hospital Los Angeles, and the Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California. Kimia Heidari is a clinical research coordinator and Thomas Chavez is a statistician and clinical research coordinator, Division of Neonatology, Children's Hospital Los Angeles, and Department of Pediatrics, Keck School of Medicine, University of Southern California. Istvan Seri is a professor of pediatrics, Weill Cornell Medical College, New York, New York; director, Sidra Neonatology Center of Excellence, Sidra Medical and Research Center, Doha, Qatar; and adjunct professor of pediatrics, Keck School of Medicine, University of Southern California. John C. Wood is a professor, Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles and Department of Biomedical Engineering, University of Southern California. Stefan Blüml is an associate professor of research radiology and biomedical engineering, Keck School of Medicine and Department of Biomedical Engineering, University of Southern California
| | - John C Wood
- Matthew Borzage is an assistant professor of research, Division of Neonatology and Department of Radiology, Children's Hospital Los Angeles, and the Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California. Kimia Heidari is a clinical research coordinator and Thomas Chavez is a statistician and clinical research coordinator, Division of Neonatology, Children's Hospital Los Angeles, and Department of Pediatrics, Keck School of Medicine, University of Southern California. Istvan Seri is a professor of pediatrics, Weill Cornell Medical College, New York, New York; director, Sidra Neonatology Center of Excellence, Sidra Medical and Research Center, Doha, Qatar; and adjunct professor of pediatrics, Keck School of Medicine, University of Southern California. John C. Wood is a professor, Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles and Department of Biomedical Engineering, University of Southern California. Stefan Blüml is an associate professor of research radiology and biomedical engineering, Keck School of Medicine and Department of Biomedical Engineering, University of Southern California
| | - Stefan Blüml
- Matthew Borzage is an assistant professor of research, Division of Neonatology and Department of Radiology, Children's Hospital Los Angeles, and the Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California. Kimia Heidari is a clinical research coordinator and Thomas Chavez is a statistician and clinical research coordinator, Division of Neonatology, Children's Hospital Los Angeles, and Department of Pediatrics, Keck School of Medicine, University of Southern California. Istvan Seri is a professor of pediatrics, Weill Cornell Medical College, New York, New York; director, Sidra Neonatology Center of Excellence, Sidra Medical and Research Center, Doha, Qatar; and adjunct professor of pediatrics, Keck School of Medicine, University of Southern California. John C. Wood is a professor, Department of Pediatrics and Radiology, Division of Pediatric Cardiology, Children's Hospital Los Angeles and Department of Biomedical Engineering, University of Southern California. Stefan Blüml is an associate professor of research radiology and biomedical engineering, Keck School of Medicine and Department of Biomedical Engineering, University of Southern California
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Coates TD, Carson S, Wood JC, Berdoukas V. Management of iron overload in hemoglobinopathies: what is the appropriate target iron level? Ann N Y Acad Sci 2017; 1368:95-106. [PMID: 27186942 DOI: 10.1111/nyas.13060] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/04/2016] [Accepted: 03/09/2016] [Indexed: 01/19/2023]
Abstract
Patients with thalassemia become iron overloaded from increased absorption of iron, ineffective erythropoiesis, and chronic transfusion. Before effective iron chelation became available, thalassemia major patients died of iron-related cardiac failure in the second decade of life. Initial treatment goals for chelation therapy were aimed at levels of ferritin and liver iron concentrations associated with prevention of adverse cardiac outcomes and avoidance of chelator toxicity. Cardiac deaths were greatly reduced and survival was much longer. Epidemiological data from the general population draw clear associations between increased transferrin saturation (and, by inference, labile iron) and early death, diabetes, and malignant transformation. The rate of cancers now seems to be significantly higher in thalassemia than in the general population. Reduction in iron can reverse many of these complications and reduce the risk of malignancy. As toxicity can result from prolonged exposure to even low levels of excess iron, and survival in thalassemia patients is now many decades, it would seem prudent to refocus attention on prevention of long-term complications of iron overload and to maintain labile iron and total body iron levels within a normal range, if expertise and resources are available to avoid complications of overtreatment.
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Affiliation(s)
- Thomas D Coates
- Section of Hematology, Children's Center for Cancer, Blood Diseases and Bone Marrow Transplantation
| | - Susan Carson
- Section of Hematology, Children's Center for Cancer, Blood Diseases and Bone Marrow Transplantation
| | - John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California
| | - Vasilios Berdoukas
- Section of Hematology, Children's Center for Cancer, Blood Diseases and Bone Marrow Transplantation
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81
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Abstract
PURPOSE 1.5T gradient echo-based R2∗ estimates are standard-of-care for assessing liver iron concentration (LIC). Despite growing popularity of 3T, echo time (TE) limitations prevent 3T liver iron quantitation in the upper half of the clinical range (LIC ⪆20 mg/g). In this work, a 3D radial pulse sequence was assessed to double the dynamic range of 3T LIC estimates. THEORY AND METHODS The minimum TE limits the dynamic range of pulse sequences to estimate R2∗. 23 chronically-transfused human volunteers were imaged with 1.5T Cartesian gradient echo (1.5T-GRE), 3T Cartesian gradient echo (3T-GRE), and 3T ultrashort TE radial (3T-UTE) pulse sequences; minimum TEs were 0.96, 0.76, and 0.19 ms, respectively. R2∗ was estimated with an exponential signal model, normalized to 1.5T equivalents, and converted to LIC. Bland-Altman analysis compared 3T-based estimates to 1.5T-GRE. RESULTS LIC by 3T-GRE was unbiased versus 1.5T-GRE for LIC ≤ 25 mg/g (sd = 9.6%); 3T-GRE failed to quantify LIC > 25 mg/g. At high iron loads, 3T-UTE was unbiased (sd = 14.5%) compared to 1.5T-GRE. Further, 3T-UTE estimated LIC up to 50 mg/g, exceeding 1.5T-GRE limits. CONCLUSION 3T-UTE imaging can reliably estimate high liver iron burdens. In conjunction with 3T-GRE, 3T-UTE allows clinical LIC estimation across a wide range of liver iron loads. Magn Reson Med 79:1579-1585, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Eamon K Doyle
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.,Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Kristin Toy
- College of Medicine, University of Toledo, Toledo, Ohio, USA
| | - Bertin Valdez
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | | | - Thomas Coates
- Division of Hematology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - John C Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.,Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
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82
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Abstract
Blood transfusion plays a prominent role in the management of patients with sickle cell disease (SCD), but causes significant iron overload. As transfusions are used to treat the severe complications of SCD, it remains difficult to distinguish whether organ damage is a consequence of iron overload or is due to the complications treated by transfusion. Better management has resulted in increased survival, but prolonged exposure to iron puts SCD patients at greater risk for iron-related complications that should be treated. The success of chelation therapy is dominated by patient adherence to prescribed treatment; thus, adjustment of drug regimens to increase adherence to treatment is critical. This review will discuss the current biology of iron homeostasis in patients with SCD and how this informs our clinical approach to treatment. We will present the clinical approach to treatment of iron overload at our centre using serial assessment of organ iron by magnetic resonance imaging.
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Affiliation(s)
- Thomas D. Coates
- Hematology Section, Children’s Centre for Cancer, Blood Diseases and Bone Marrow Transplantation, University of Southern California, Los Angeles California, USA
| | - John C. Wood
- Division of Cardiology, at the Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles California, USA
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83
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Šmíd M, Gallardo González I, Ekerfelt H, Björklund Svensson J, Hansson M, Wood JC, Persson A, Mangles SPD, Lundh O, Falk K. Highly efficient angularly resolving x-ray spectrometer optimized for absorption measurements with collimated sources. Rev Sci Instrum 2017; 88:063102. [PMID: 28667973 DOI: 10.1063/1.4986464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Highly collimated betatron radiation from a laser wakefield accelerator is a promising tool for spectroscopic measurements. Therefore, there is a requirement to create spectrometers suited to the unique properties of such a source. We demonstrate a spectrometer which achieves an energy resolution of <5 eV at 9 keV (E∕ΔE>1800) and is angularly resolving the x-ray emission allowing the reference and spectrum to be recorded at the same time. The single photon analysis is used to significantly reduce the background noise. Theoretical performance of various configurations of the spectrometer is calculated by a ray-tracing algorithm. The properties and performance of the spectrometer including the angular and spectral resolution are demonstrated experimentally on absorption above the K-edge of a Cu foil backlit by a laser-produced betatron radiation x-ray beam.
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Affiliation(s)
- M Šmíd
- Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague, Czech Republic
| | | | - H Ekerfelt
- Department of Physics, Lund University, P.O. Box 118, S-22100 Lund, Sweden
| | | | - M Hansson
- Department of Physics, Lund University, P.O. Box 118, S-22100 Lund, Sweden
| | - J C Wood
- John Adams Institute for Accelerator Science, Imperial College London, SW7 2AZ London, United Kingdom
| | - A Persson
- Department of Physics, Lund University, P.O. Box 118, S-22100 Lund, Sweden
| | - S P D Mangles
- John Adams Institute for Accelerator Science, Imperial College London, SW7 2AZ London, United Kingdom
| | - O Lundh
- Department of Physics, Lund University, P.O. Box 118, S-22100 Lund, Sweden
| | - K Falk
- Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague, Czech Republic
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84
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Chalacheva P, Khaleel M, Sunwoo J, Shah P, Detterich JA, Kato RM, Thuptimdang W, Meiselman HJ, Sposto R, Tsao J, Wood JC, Zeltzer L, Coates TD, Khoo MCK. Biophysical markers of the peripheral vasoconstriction response to pain in sickle cell disease. PLoS One 2017; 12:e0178353. [PMID: 28542469 PMCID: PMC5443571 DOI: 10.1371/journal.pone.0178353] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/11/2017] [Indexed: 02/07/2023] Open
Abstract
Painful vaso-occlusive crisis (VOC), a complication of sickle cell disease (SCD), occurs when sickled red blood cells obstruct flow in the microvasculature. We postulated that exaggerated sympathetically mediated vasoconstriction, endothelial dysfunction and the synergistic interaction between these two factors act together to reduce microvascular flow, promoting regional vaso-occlusions, setting the stage for VOC. We previously found that SCD subjects had stronger vasoconstriction response to pulses of heat-induced pain compared to controls but the relative degrees to which autonomic dysregulation, peripheral vascular dysfunction and their interaction are present in SCD remain unknown. In the present study, we employed a mathematical model to decompose the total vasoconstriction response to pain into: 1) the neurogenic component, 2) the vascular response to blood pressure, 3) respiratory coupling and 4) neurogenic-vascular interaction. The model allowed us to quantify the contribution of each component to the total vasoconstriction response. The most salient features of the components were extracted to represent biophysical markers of autonomic and vascular impairment in SCD and controls. These markers provide a means of phenotyping severity of disease in sickle-cell anemia that is based more on underlying physiology than on genotype. The marker of the vascular component (BMv) showed stronger contribution to vasoconstriction in SCD than controls (p = 0.0409), suggesting a dominant myogenic response in the SCD subjects as a consequence of endothelial dysfunction. The marker of neurogenic-vascular interaction (BMn-v) revealed that the interaction reinforced vasoconstriction in SCD but produced vasodilatory response in controls (p = 0.0167). This marked difference in BMn-v suggests that it is the most sensitive marker for quantifying combined alterations in autonomic and vascular function in SCD in response to heat-induced pain.
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Affiliation(s)
- Patjanaporn Chalacheva
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
| | - Maha Khaleel
- Division of Hematology, Oncology and Blood & Marrow Transplantation, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Los Angeles, California, United States of America
| | - John Sunwoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
| | - Payal Shah
- Division of Hematology, Oncology and Blood & Marrow Transplantation, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Los Angeles, California, United States of America
| | - Jon A. Detterich
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California, United States of America
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Roberta M. Kato
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Division of Pulmonology, Children’s Hospital Los Angeles, Los Angeles, California, United States of America
| | - Wanwara Thuptimdang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
| | - Herbert J. Meiselman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Richard Sposto
- Division of Hematology, Oncology and Blood & Marrow Transplantation, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Los Angeles, California, United States of America
- Department of Preventative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Jennie Tsao
- Pediatric Pain Program, David Geffen School of Medicine, University of California at Los Angeles, California, United States of America
| | - John C. Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California, United States of America
| | - Lonnie Zeltzer
- Pediatric Pain Program, David Geffen School of Medicine, University of California at Los Angeles, California, United States of America
| | - Thomas D. Coates
- Division of Hematology, Oncology and Blood & Marrow Transplantation, Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Los Angeles, California, United States of America
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Michael C. K. Khoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
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85
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Krittayaphong R, Viprakasit V, Saiviroonporn P, Wangworatrakul W, Wood JC. Serum ferritin in the diagnosis of cardiac and liver iron overload in thalassaemia patients real-world practice: a multicentre study. Br J Haematol 2017; 182:301-305. [PMID: 28543061 DOI: 10.1111/bjh.14776] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Rungroj Krittayaphong
- Division of Cardiology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Vip Viprakasit
- Division of Haematology, Department of Paediatrics, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Pairash Saiviroonporn
- Department of Radiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Wipaporn Wangworatrakul
- Division of Cardiology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, CA, USA
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Kali A, Cokic I, Tang R, Dohnalkova A, Kovarik L, Yang HJ, Kumar A, Prato FS, Wood JC, Underhill D, Marbán E, Dharmakumar R. Persistent Microvascular Obstruction After Myocardial Infarction Culminates in the Confluence of Ferric Iron Oxide Crystals, Proinflammatory Burden, and Adverse Remodeling. Circ Cardiovasc Imaging 2017; 9:CIRCIMAGING.115.004996. [PMID: 27903536 DOI: 10.1161/circimaging.115.004996] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 08/26/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Emerging evidence indicates that persistent microvascular obstruction (PMO) is more predictive of major adverse cardiovascular events than myocardial infarct (MI) size. But it remains unclear how PMO, a phenomenon limited to the acute/subacute period of MI, drives adverse remodeling in chronic MI setting. We hypothesized that PMO resolves into chronic iron crystals within MI territories, which in turn are proinflammatory and favor adverse remodeling post-MI. METHODS AND RESULTS Canines (n=40) were studied with cardiac magnetic resonance imaging to characterize the spatiotemporal relationships among PMO, iron deposition, infarct resorption, and left ventricular remodeling between day 7 (acute) and week 8 (chronic) post-MI. Histology was used to assess iron deposition and to examine relationships between iron content with macrophage infiltration, proinflammatory cytokine synthesis, and matrix metalloproteinase activation. Atomic resolution transmission electron microscopy was used to determine iron crystallinity, and energy-dispersive X-ray spectroscopy was used to identify the chemical composition of the iron composite. PMO with or without reperfusion hemorrhage led to chronic iron deposition, and the extent of this deposition was strongly related to PMO volume (r>0.8). Iron deposits were found within macrophages as aggregates of nanocrystals (≈2.5 nm diameter) in the ferric state. Extent of iron deposits was strongly correlated with proinflammatory burden, collagen-degrading enzyme activity, infarct resorption, and adverse structural remodeling (r>0.5). CONCLUSIONS Crystallized iron deposition from PMO is directly related to proinflammatory burden, infarct resorption, and adverse left ventricular remodeling in the chronic phase of MI in canines. Therapeutic strategies to combat adverse remodeling could potentially benefit from taking into account the chronic iron-driven inflammatory process.
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Affiliation(s)
- Avinash Kali
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Ivan Cokic
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Richard Tang
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Alice Dohnalkova
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Libor Kovarik
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Hsin-Jung Yang
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Andreas Kumar
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Frank S Prato
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - John C Wood
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - David Underhill
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Eduardo Marbán
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.)
| | - Rohan Dharmakumar
- From the Cedars-Sinai Medical Center, Los Angeles, CA (A.K., I.C., R.T., H.-J.Y., A.K., D.U., E.M., R.D.); University of California, Los Angeles (A.K., H.-J.Y., D.U., E.M., R.D.); Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA (A.D., L.K.); Lawson Health Research Institute, University of Western Ontario, London, Canada (F.S.P.); and Children's Hospital Los Angeles, CA (J.C.W.).
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87
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Choi S, Bush AM, Borzage MT, Joshi AA, Mack WJ, Coates TD, Leahy RM, Wood JC. Hemoglobin and mean platelet volume predicts diffuse T1-MRI white matter volume decrease in sickle cell disease patients. Neuroimage Clin 2017; 15:239-246. [PMID: 28540180 PMCID: PMC5430155 DOI: 10.1016/j.nicl.2017.04.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/13/2017] [Accepted: 04/25/2017] [Indexed: 02/01/2023]
Abstract
Sickle cell disease (SCD) is a life-threatening genetic condition. Patients suffer from chronic systemic and cerebral vascular disease that leads to early and cumulative neurological damage. Few studies have quantified the effects of this disease on brain morphometry and even fewer efforts have been devoted to older patients despite the progressive nature of the disease. This study quantifies global and regional brain volumes in adolescent and young adult patients with SCD and racially matched controls with the aim of distinguishing between age related changes associated with normal brain maturation and damage from sickle cell disease. T1 weighted images were acquired on 33 clinically asymptomatic SCD patients (age = 21.3 ± 7.8; F = 18, M = 15) and 32 racially matched control subjects (age = 24.4 ± 7.5; F = 22, M = 10). Exclusion criteria included pregnancy, previous overt stroke, acute chest, or pain crisis hospitalization within one month. All brain volume comparisons were corrected for age and sex. Globally, grey matter volume was not different but white matter volume was 8.1% lower (p = 0.0056) in the right hemisphere and 6.8% (p = 0.0068) in the left hemisphere in SCD patients compared with controls. Multivariate analysis retained hemoglobin (β = 0.33; p = 0.0036), sex (β = 0.35; p = 0.0017) and mean platelet volume (β = 0.27; p = 0.016) as significant factors in the final prediction model for white matter volume for a combined r2 of 0.37 (p < 0.0001). Lower white matter volume was confined to phylogenetically younger brain regions in the anterior and middle cerebral artery distributions. Our findings suggest that there are diffuse white matter abnormalities in SCD patients, especially in the frontal, parietal and temporal lobes, that are associated with low hemoglobin levels and mean platelet volume. The pattern of brain loss suggests chronic microvascular insufficiency and tissue hypoxia as the causal mechanism. However, longitudinal studies of global and regional brain morphometry can help us give further insights on the pathophysiology of SCD in the brain. Total white matter brain volume is decreased in sickle cell disease patients. Global white matter decrease is found to be due to anemia. Diffuse WM volume decrease is found especially in watershed areas. Diffuse WM volume decrease spatially colocalize with silent stroke in SCD patients.
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Key Words
- ACA, anterior cerebral artery
- GM, grey matter
- Hemoglobin
- HgB, hemoglobin
- MCA, middle cerebral artery
- MPV, mean platelet volume
- MRI, magnetic resonance imaging
- Mean platelet volume
- PCA, posterior cerebral artery
- ROI, region of interest
- SCD, sickle cell disease
- Sickle cell disease
- Structural MRI
- WM, white matter
- WMHI, white matter hyperintensities
- White matter
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Affiliation(s)
- Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, 3641 Watt Way, HNB 120, Los Angeles, CA 90089-2520, USA; Signal and Image Processing Institution, University of Southern California, 3740 McClintock Avenue, EEB 400, Los Angeles, CA 90089-2560, USA; Department of Pediatrics and Radiology, Children's Hospital Los Angeles USC, 4650 Sunset Blvd., MS #81, Los Angeles, CA 90027, USA.
| | - Adam M Bush
- Biomedical Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA 90089, USA.
| | - Matthew T Borzage
- Department of Pediatrics and Radiology, Children's Hospital Los Angeles USC, 4650 Sunset Blvd., MS #81, Los Angeles, CA 90027, USA.
| | - Anand A Joshi
- Signal and Image Processing Institution, University of Southern California, 3740 McClintock Avenue, EEB 400, Los Angeles, CA 90089-2560, USA.
| | - William J Mack
- Department of Neurosurgery, University of Southern California Keck School of Medicine, 1200 North State St., Suite 3300, Los Angeles, CA 90033, USA.
| | - Thomas D Coates
- Hematology/Oncology, Children's Hospital Los Angeles, 4650 Sunset Blvd. MS #54, Los Angeles, CA 90027, USA.
| | - Richard M Leahy
- Signal and Image Processing Institution, University of Southern California, 3740 McClintock Avenue, EEB 400, Los Angeles, CA 90089-2560, USA; Biomedical Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA 90089, USA.
| | - John C Wood
- Department of Pediatrics and Radiology, Children's Hospital Los Angeles USC, 4650 Sunset Blvd., MS #81, Los Angeles, CA 90027, USA; Biomedical Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA 90089, USA.
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88
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Pepe A, Meloni A, Rossi G, Midiri M, Missere M, Valeri G, Sorrentino F, D’Ascola DG, Spasiano A, Filosa A, Cuccia L, Dello Iacono N, Forni G, Caruso V, Maggio A, Pitrolo L, Peluso A, De Marchi D, Positano V, Wood JC. Prediction of cardiac complications for thalassemia major in the widespread cardiac magnetic resonance era: a prospective multicentre study by a multi-parametric approach. Eur Heart J Cardiovasc Imaging 2017; 19:299-309. [DOI: 10.1093/ehjci/jex012] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/16/2017] [Indexed: 01/24/2023] Open
Affiliation(s)
- Alessia Pepe
- CMR Unit, Fondazione G. Monasterio CNR-Regione Toscana, Via Moruzzi 1—56124, Pisa, Italy
| | - Antonella Meloni
- CMR Unit, Fondazione G. Monasterio CNR-Regione Toscana, Via Moruzzi 1—56124, Pisa, Italy
| | - Giuseppe Rossi
- Epidemiology and Biostatistics Unit, Institute of Clinical Physiology, CNR, Pisa, Italy
| | - Massimo Midiri
- Istituto di Radiologia, Policlinico ‘Giaccone’, Palermo, Italy
| | | | | | | | | | - Anna Spasiano
- UOSD Centro per le Microcitemie, AORN Cardarelli, Napoli, Italy
| | - Aldo Filosa
- UOSD Centro per le Microcitemie, AORN Cardarelli, Napoli, Italy
| | - Liana Cuccia
- U.O.C. Ematologia con Talassemia, Ospedale Civico, Palermo, Italy
| | - Nicola Dello Iacono
- D.H. Thalassemia, Ospedale Casa Sollievo della Sofferenza IRCCS Opera di Padre Pio, San Giovanni Rotondo, Italy
| | - Gianluca Forni
- Centro della Microcitemia e delle Anemie Congenite, Ospedale Galliera, Genova, Italy
| | | | - Aurelio Maggio
- Ematologia II con Talassemia, Ospedali Riuniti ‘Villa Sofia-Cervello’, Palermo, Italy
| | - Lorella Pitrolo
- Ematologia II con Talassemia, Ospedali Riuniti ‘Villa Sofia-Cervello’, Palermo, Italy
| | - Angelo Peluso
- Microcitemia, Azienda Unità Sanitaria Locale TA/1, Taranto, Italy
| | - Daniele De Marchi
- CMR Unit, Fondazione G. Monasterio CNR-Regione Toscana, Via Moruzzi 1—56124, Pisa, Italy
| | - Vincenzo Positano
- CMR Unit, Fondazione G. Monasterio CNR-Regione Toscana, Via Moruzzi 1—56124, Pisa, Italy
| | - John C Wood
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, CA, USA
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89
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Bush AM, Borzage MT, Choi S, Václavů L, Tamrazi B, Nederveen AJ, Coates TD, Wood JC. Determinants of resting cerebral blood flow in sickle cell disease. Am J Hematol 2016; 91:912-7. [PMID: 27263497 DOI: 10.1002/ajh.24441] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 11/11/2022]
Abstract
Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2) = 0.69, P < 0.0001). Brain oxygen delivery, the product of CBF and oxygen content, was normal in all groups. Brain composition, specifically the relative amounts of grey and white matter, was the next strongest CBF predictor, presumably by influencing cerebral metabolic rate. Grey matter/white matter ratio and CBF declined monotonically until the age of 25 in all subjects, consistent with known maturational changes in brain composition. Further CBF reductions were observed with age in subjects older than 35 years of age, likely reflecting microvascular aging. On multivariate regression, CBF was independent of disease state, hemoglobin S, hemoglobin F, reticulocyte count and cell free hemoglobin, suggesting that it is regulated similarly in patients and control subjects. In conclusion, sickle cell disease patients had sufficient oxygen delivery at rest, but accomplish this only by marked increases in their resting CBF, potentially limiting their ability to further augment flow in response to stress. Am. J. Hematol. 91:912-917, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Adam M. Bush
- Department of Biomedical Engineering; University of Southern California; California
| | - Matthew T. Borzage
- Division of Neonatology and Radiology; Children's Hospital Los Angeles; California
| | - Soyoung Choi
- Neurosciences Program; University of Southern California; California
| | - Lena Václavů
- Department of Radiology; Academic Medical Center; Amsterdam
| | - Benita Tamrazi
- Department of Radiology; Children's Hospital Los Angeles; California
| | | | - Thomas D. Coates
- Section of Hematology; Children's Hospital Los Angeles; California
| | - John C. Wood
- Department of Radiology; Children's Hospital Los Angeles; California
- Division of Cardiology; Children's Hospital Los Angeles; California
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90
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Bush A, Borzage M, Detterich J, Kato RM, Meiselman HJ, Coates T, Wood JC. Empirical model of human blood transverse relaxation at 3 T improves MRI T 2 oximetry. Magn Reson Med 2016; 77:2364-2371. [PMID: 27385283 DOI: 10.1002/mrm.26311] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/28/2016] [Accepted: 05/25/2016] [Indexed: 11/06/2022]
Abstract
PURPOSE We sought a human blood T2 -oximetery calibration curve over the wide range of hematocrits commonly found in anemic patients applicable with T2 relaxation under spin tagging (TRUST). METHODS Blood was drawn from five healthy control subjects. Ninety-three in vitro blood transverse relaxation (T2b ) measurements were performed at 37°C over a broad range of hematocrits (10-55%) and oxygen saturations (14-100%) at 3 Tesla (T). In vivo TRUST was performed on 35 healthy African American control subjects and 11 patients with chronic anemia syndromes. RESULTS 1/T2 rose linearly with hematocrit (r2 = 0.96), for fully saturated blood. Upon desaturation, 1/T2 rose linearly with the square of the oxygen extraction, (1-Y)2 , and the slope was linearly proportional to hematocrit (r2 = 0.88). The resulting bilinear model between 1/T2 , (1-Y)2 , and hematocrit had a combined r2 of 0.96 and a coefficient of variation of 6.1%. Using the in vivo data, the bilinear model had significantly lower bias and variability than existing calibrations, particularly for low hematocrits. In vivo Bland Altman analysis demonstrated clinically relevant bias that was -6% (absolute saturation) for hematocrits near 30% and rose to + 6% for hematocrits near 45%. CONCLUSION This work introduces a robust bilinear calibration model that should be used for MRI oximetry. Magn Reson Med 77:2364-2371, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Adam Bush
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA.,Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA
| | - Matthew Borzage
- Division of Neonatology, Children's Hospital Los Angeles, Los Angeles, California, USA.,Department of Radiology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - John Detterich
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Roberta M Kato
- Division of Pulmonary, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Herbert J Meiselman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Thomas Coates
- Division of Hematology/Oncology, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA.,Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA
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91
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Bacigalupo L, Paparo F, Zefiro D, Viberti CM, Cevasco L, Gianesin B, Pinto VM, Rollandi GA, Wood JC, Forni GL. Comparison between different software programs and post-processing techniques for the MRI quantification of liver iron concentration in thalassemia patients. Radiol Med 2016; 121:751-62. [PMID: 27334009 DOI: 10.1007/s11547-016-0661-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 06/01/2016] [Indexed: 01/19/2023]
Abstract
PURPOSE In magnetic resonance imaging (MRI) relaxometry, various software programs are available to perform R2* measurements and to estimate the liver iron concentration (LIC). The main objective of our study was to compare R2* LIC values, obtained with three different software programs based on specific decay models and calibration curves, with LIC estimates provided by R2-relaxometry (FerriScan). METHODS This retrospective study included 15 patients with 15 baseline MRIs and 34 serial examinations. R2* LIC estimates were calculated using the FuncTool, CMRtools/Thalassemia Tools and Quanta Hematology programs. Longitudinal LIC changes (ΔLIC) were calculated using the subset of 34 serial MRIs. RESULTS After Bland-Altman analysis on baseline data, Quanta Hematology, which employs the monoexponential-plus-constant fit, produced the lowest mean difference [0.01 ± 0.14 log(mg/gdw)] with the closest limits of agreement. In the longitudinal setting, Quanta Hematology again gave the lowest mean difference between R2 and R2* LIC (0.1 ± 2.6 mg/gdw). Using FerriScan as reference, the value of concordant directional ΔLIC changes was the same for all programs (27/34, 85.7 %). CONCLUSIONS R2* LICs are higher than R2 LICs at iron levels <7 mg/gdw, while R2 LIC averages higher than R2* LIC with increasing iron load. The monoexponential-plus-constant model provided the best agreement with R2 LIC estimates.
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Affiliation(s)
- Lorenzo Bacigalupo
- Radiology Unit, Department of Diagnostic Imaging, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy.
| | - Francesco Paparo
- Radiology Unit, Department of Diagnostic Imaging, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
| | - Daniele Zefiro
- Department of Medical Physics, ASL n.5 "Spezzino", Via XXIV Maggio 139, 19124, La Spezia, Italy
| | - Carlo Maria Viberti
- Medical Physics Unit, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
| | - Luca Cevasco
- Radiology Unit, Department of Diagnostic Imaging, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
| | - Barbara Gianesin
- Medical Physics Unit, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
| | - Valeria Maria Pinto
- Microcitemia and Hereditary Anaemias Unit, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
| | - Gian Andrea Rollandi
- Radiology Unit, Department of Diagnostic Imaging, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
| | - John C Wood
- Department of Radiology, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Gian Luca Forni
- Microcitemia and Hereditary Anaemias Unit, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy
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92
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Václavů L, van der Land V, Heijtel DFR, van Osch MJP, Cnossen MH, Majoie CBLM, Bush A, Wood JC, Fijnvandraat KJ, Mutsaerts HJMM, Nederveen AJ. In Vivo T1 of Blood Measurements in Children with Sickle Cell Disease Improve Cerebral Blood Flow Quantification from Arterial Spin-Labeling MRI. AJNR Am J Neuroradiol 2016; 37:1727-32. [PMID: 27231223 DOI: 10.3174/ajnr.a4793] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/24/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND PURPOSE Children with sickle cell disease have low hematocrit and elevated CBF, the latter of which can be assessed with arterial spin-labeling MR imaging. Quantitative CBF values are obtained by using an estimation of the longitudinal relaxation time of blood (T1blood). Because T1blood depends on hematocrit in healthy individuals, we investigated the importance of measuring T1blood in vivo with MR imaging versus calculating it from hematocrit or assuming an adult fixed value recommended by the literature, hypothesizing that measured T1blood would be the most suited for CBF quantification in children with sickle cell disease. MATERIALS AND METHODS Four approaches for T1blood estimation were investigated in 39 patients with sickle cell disease and subsequently used in the CBF quantification from arterial spin-labeling MR imaging. First, we used 1650 ms as recommended by the literature (T1blood-fixed); second, T1blood calculated from hematocrit measured in patients (T1blood-hematocrit); third, T1blood measured in vivo with a Look-Locker MR imaging sequence (T1blood-measured); and finally, a mean value from T1blood measured in this study in children with sickle cell disease (T1blood-sickle cell disease). Quantitative flow measurements acquired with phase-contrast MR imaging served as reference values for CBF. RESULTS T1blood-measured (1818 ± 107 ms) was higher than the literature recommended value of 1650 ms, was significantly lower than T1blood-hematocrit (2058 ± 123 ms, P < .001), and, most interesting, did not correlate with hematocrit measurements. Use of either T1blood-measured or T1blood-sickle cell disease provided the best agreement on CBF between arterial-spin labeling and phase-contrast MR imaging reference values. CONCLUSIONS This work advocates the use of patient-specific measured T1blood or a standardized value (1818 ms) in the quantification of CBF from arterial spin-labeling in children with SCD.
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Affiliation(s)
- L Václavů
- From the Department of Radiology (L.V., D.F.R.H., C.B.L.M.M., H.J.M.M.M., A.J.N.), Academic Medical Center, Amsterdam, the Netherlands
| | - V van der Land
- Department of Pediatric Hematology (V.v.d.L., K.J.F.), Emma Children's Hospital, Academic Medical Center, Amsterdam, the Netherlands
| | - D F R Heijtel
- From the Department of Radiology (L.V., D.F.R.H., C.B.L.M.M., H.J.M.M.M., A.J.N.), Academic Medical Center, Amsterdam, the Netherlands
| | - M J P van Osch
- C.J. Gorter Center for High Field MRI (M.J.P.v.O.), Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - M H Cnossen
- Department of Pediatric Hematology (M.H.C.), Erasmus University Medical Center-Sophia Children's Hospital, Rotterdam, the Netherlands
| | - C B L M Majoie
- From the Department of Radiology (L.V., D.F.R.H., C.B.L.M.M., H.J.M.M.M., A.J.N.), Academic Medical Center, Amsterdam, the Netherlands
| | - A Bush
- Department of Biomedical Engineering (A.B.), Viterbi School of Engineering, University of Southern California, Los Angeles, California
| | - J C Wood
- Department of Pediatrics (J.C.W.), Children's Hospital Los Angeles, Los Angeles, California
| | - K J Fijnvandraat
- Department of Pediatric Hematology (V.v.d.L., K.J.F.), Emma Children's Hospital, Academic Medical Center, Amsterdam, the Netherlands
| | - H J M M Mutsaerts
- From the Department of Radiology (L.V., D.F.R.H., C.B.L.M.M., H.J.M.M.M., A.J.N.), Academic Medical Center, Amsterdam, the Netherlands Sunnybrook Research Institute (H.J.M.M.M.), Toronto, Ontario, Canada
| | - A J Nederveen
- From the Department of Radiology (L.V., D.F.R.H., C.B.L.M.M., H.J.M.M.M., A.J.N.), Academic Medical Center, Amsterdam, the Netherlands
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Borzage MT, Bush AM, Choi S, Nederveen AJ, Václavů L, Coates TD, Wood JC. Predictors of cerebral blood flow in patients with and without anemia. J Appl Physiol (1985) 2016; 120:976-81. [PMID: 26796758 PMCID: PMC4835904 DOI: 10.1152/japplphysiol.00994.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/19/2016] [Indexed: 11/22/2022] Open
Abstract
Sickle cell disease (SCD) is the most common cause of stroke in childhood and results primarily from a mismatch of cerebral oxygen supply and demand rather than arterial obstruction. However, resting cerebral blood flow (CBF) has not been examined in the general African American population, in whom obesity, hypertension, cerebrovascular disease, and diminished cerebrovascular reserve capacity are common. To better understand the underlying physiological substrate upon which SCD is superimposed, we measured CBF in 32 young (age 28 ± 10 yr), asymptomatic African American subjects with and without sickle cell trait (n= 14). To characterize the effects of chronic anemia, in isolation of sickle hemoglobin we also studied a cohort of 13 subjects with thalassemia major (n= 10), dyserythropoetic anemia (n= 1), or spherocytosis (n= 2). Blood was analyzed for complete blood count, hemoglobin electrophoresis, cell free hemoglobin, and lactate dehydrogenase. Multivariate regression analysis showed that oxygen content was the strongest predictor of CBF (r(2)= 0.33,P< 0.001). CBF declined rapidly in the second and third decades of life, but this drop was explained by reductions in cerebral gray matter. However, age effects persisted after correction for brain composition, possibly representing microvascular impairment. CBF was independent of viscosity, hemoglobin S%, and body mass index. Hyperoxia resulted in reduced CBF by 12.6% (P= 0.0002), and CBF changes were proportional to baseline oxygen content (r(2)= 0.16,P= 0.02). These data suggest that these hemoglobin subtypes do not alter the normal CBF regulation of the balance of oxygen supply and demand.
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Affiliation(s)
- Matthew T Borzage
- Division of Neonatology and Radiology, Children's Hospital Los Angeles, Los Angeles, California
| | - Adam M Bush
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California
| | - Aart J Nederveen
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Lena Václavů
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Thomas D Coates
- Division of Hematology, Children's Hospital Los Angeles, Los Angeles, California; and
| | - John C Wood
- Division of Cardiology and Radiology, Children's Hospital Los Angeles, Los Angeles, California
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94
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Cheng AL, Takao CM, Wenby RB, Meiselman HJ, Wood JC, Detterich JA. Elevated Low-Shear Blood Viscosity is Associated with Decreased Pulmonary Blood Flow in Children with Univentricular Heart Defects. Pediatr Cardiol 2016; 37:789-801. [PMID: 26888364 PMCID: PMC5769474 DOI: 10.1007/s00246-016-1352-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/04/2016] [Indexed: 12/28/2022]
Abstract
After the Fontan procedure, patients with univentricular hearts can experience long-term complications due to chronic low-shear non-pulsatile pulmonary blood flow. We sought to evaluate hemorheology and its relationship to hemodynamics in children with univentricular hearts. We hypothesized that low-shear blood viscosity and red blood cell (RBC) aggregation would be associated with increased pulmonary vascular resistance (PVR) and decreased pulmonary blood flow (PBF). We performed a cross-sectional analysis of 62 children undergoing cardiac catheterization-20 with isolated atrial septal defect (ASD), 22 status post Glenn procedure (Glenn), and 20 status post Fontan procedure (Fontan). Shear-dependent blood viscosity, RBC aggregation and deformability, complete blood count, coagulation panel, metabolic panel, fibrinogen, and erythrocyte sedimentation rate were measured. PVR and PBF were calculated using the Fick equation. Group differences were analyzed by ANOVA and correlations by linear regression. Blood viscosity at all shear rates was higher in Glenn and Fontan, partially due to normocytic anemia in ASD. RBC aggregation and deformability were similar between all groups. Low-shear viscosity negatively correlated with PBF in Glenn and Fontan only (R (2) = 0.27, p < 0.001); it also negatively correlated with pulmonary artery pressure in Glenn (R (2) = 0.15, p = 0.01), and positively correlated with PVR in Fontan (R (2) = 0.28, p = 0.02). Our data demonstrate that elevated low-shear blood viscosity is associated with negative hemodynamic perturbations in a passive univentricular pulmonary circulation, but not in a pulsatile biventricular pulmonary circulation.
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Affiliation(s)
- Andrew L. Cheng
- Division of Pediatric Cardiology, Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, 4650 Sunset Blvd., Mailstop #34, Los Angeles, CA 90036, USA
| | - Cheryl M. Takao
- Division of Pediatric Cardiology, Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, 4650 Sunset Blvd., Mailstop #34, Los Angeles, CA 90036, USA
| | - Rosalinda B. Wenby
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Herbert J. Meiselman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - John C. Wood
- Division of Pediatric Cardiology, Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, 4650 Sunset Blvd., Mailstop #34, Los Angeles, CA 90036, USA
| | - Jon A. Detterich
- Division of Pediatric Cardiology, Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, 4650 Sunset Blvd., Mailstop #34, Los Angeles, CA 90036, USA,Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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95
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Wood JC, Cohen AR, Pressel SL, Aygun B, Imran H, Luchtman-Jones L, Thompson AA, Fuh B, Schultz WH, Davis BR, Ware RE. Organ iron accumulation in chronically transfused children with sickle cell anaemia: baseline results from the TWiTCH trial. Br J Haematol 2015; 172:122-30. [PMID: 26523836 DOI: 10.1111/bjh.13791] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 08/25/2015] [Indexed: 10/22/2022]
Abstract
Transcranial Doppler (TCD) With Transfusions Changing to Hydroxyurea (TWiTCH) trial is a randomized, open-label comparison of hydroxycarbamide (also termed hydroxyurea) versus continued chronic transfusion therapy for primary stroke prevention in patients with sickle cell anaemia (SCA) and abnormal TCD. Severity and location of iron overload is an important secondary outcome measure. We report the baseline findings of abdominal organ iron burden in 121 participants. At enrollment, patients were young (9·8 ± 2·9 years), predominantly female (60:40), and previously treated with transfusions (4·1 ± 2·4 years) and iron chelation (3·1 ± 2·1 years). Liver iron concentration (LIC; 9·0 ± 6·6 mg/g dry weight) and serum ferritin were moderately elevated (2696 ± 1678 μg/l), but transferrin was incompletely saturated (47·2 ± 23·6%). Spleen R2* was 509 ± 399 Hz (splenic iron ~13·9 mg/g) and correlated with LIC (r(2) = 0·14, P = 0·0008). Pancreas R2* was increased in 38·3% of patients but not to levels associated with endocrine toxicity. Kidney R2* was increased in 80·7% of patients; renal iron correlated with markers of intravascular haemolysis and was elevated in patients with increased urine albumin-creatinine ratios. Extra-hepatic iron deposition is common among children with SCA who receive chronic transfusions, and could potentiate oxidative stress caused by reperfusion injury and decellularized haemoglobin.
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Affiliation(s)
- John C Wood
- Department of Cardiology, Childrens Hospital of Los Angeles, Los Angeles, CA, USA
| | - Alan R Cohen
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Sara L Pressel
- Department of Biostatistics, University of Texas Health Science Center, Houston, TX, USA
| | - Banu Aygun
- Department of Pediatrics, Cohen Children's Medical Center of NY, New Hyde Park, NY, USA
| | - Hamayun Imran
- Department of Pediatrics, University of South Alabama, Mobile, AL, USA
| | - Lori Luchtman-Jones
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnnati, OH, USA
| | - Alexis A Thompson
- Department of Pediatrics, Anna and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Beng Fuh
- Department of Biostatistics, University of Texas Health Science Center, Houston, TX, USA
| | - William H Schultz
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnnati, OH, USA
| | - Barry R Davis
- Department of Biostatistics, University of Texas Health Science Center, Houston, TX, USA
| | - Russell E Ware
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnnati, OH, USA
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96
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Wood JC, Pressel S, Rogers ZR, Odame I, Kwiatkowski JL, Lee MT, Owen WC, Cohen AR, St. Pierre T, Heeney MM, Schultz WH, Davis BR, Ware RE. Liver iron concentration measurements by MRI in chronically transfused children with sickle cell anemia: baseline results from the TWiTCH trial. Am J Hematol 2015; 90:806-10. [PMID: 26087998 DOI: 10.1002/ajh.24089] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 06/10/2015] [Accepted: 06/12/2015] [Indexed: 01/19/2023]
Abstract
Noninvasive, quantitative, and accurate assessment of liver iron concentration (LIC) by MRI is useful for patients receiving transfusions, but R2 and R2* MRI techniques have not been systematically compared in sickle cell anemia (SCA). We report baseline LIC results from the TWiTCH trial, which compares hydroxyurea with blood transfusion treatment for primary stroke prophylaxis assessed by transcranial Doppler sonography in pediatric SCA patients. Liver R2 was collected and processed using a FDA-approved commercial process (FerriScan®), while liver R2* quality control and processing were performed by a Core Laboratory blinded to clinical site and patient data. Baseline LIC studies using both MRI techniques were available for 120 participants. LICR2* and LICR2 results were highly correlated (r(2) = 0.93). A proportional bias of LIC(R2*)/LIC(R2), decreasing with average LIC, was observed. Systematic differences between LICR2* and LICR2 were also observed by MRI manufacturer. Importantly, LICR2* and LICR2 estimates had broad 95% limits of agreement with respect to each other. We recommend LICR2 and LICR2* not be used interchangeably in SCA patients to follow individual patient trends in iron burden.
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Affiliation(s)
- John C. Wood
- Children's Hospital Los Angeles; Los Angeles California
| | - Sara Pressel
- The University of Texas Health Science Center; Houston Texas
| | - Zora R. Rogers
- University of Texas Southwestern Medical Center; Dallas Texas
| | - Isaac Odame
- Division of Haematology/Oncology, University of Toronto, The Hospital for Sick Children; Toronto Canada
| | | | | | - William C. Owen
- Children's Hospital of the King's Daughters; Norfolk Virginia
| | - Alan R. Cohen
- School of Physics; University of Western Australia; Crawley Australia
| | | | | | | | - Barry R. Davis
- The University of Texas Health Science Center; Houston Texas
| | - Russell E. Ware
- Cincinnati Children's Hospital Medical Center; Cincinnati Ohio
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97
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Cole JM, Wood JC, Lopes NC, Poder K, Abel RL, Alatabi S, Bryant JSJ, Jin A, Kneip S, Mecseki K, Symes DR, Mangles SPD, Najmudin Z. Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone. Sci Rep 2015; 5:13244. [PMID: 26283308 PMCID: PMC5289072 DOI: 10.1038/srep13244] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 07/20/2015] [Indexed: 12/22/2022] Open
Abstract
A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications.
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Affiliation(s)
- J M Cole
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - J C Wood
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - N C Lopes
- 1] The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK [2] GoLP, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Portugal
| | - K Poder
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - R L Abel
- Department of Surgery and Cancer, MSk Laboratory, Charing Cross Hospital, Imperial College London, London W6 8RF, UK
| | - S Alatabi
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - J S J Bryant
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - A Jin
- Department of Mechanical Engineering, City and Guilds Building, Imperial College London, London SW7 2AZ, UK
| | - S Kneip
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - K Mecseki
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - D R Symes
- Central Laser Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - S P D Mangles
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
| | - Z Najmudin
- The John Adams Institute for Accelerator Science, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK
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98
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Chalacheva P, Kato RM, Sangkatumvong S, Detterich J, Bush A, Wood JC, Meiselman H, Coates TD, Khoo MCK. Autonomic responses to cold face stimulation in sickle cell disease: a time-varying model analysis. Physiol Rep 2015; 3:3/7/e12463. [PMID: 26177958 PMCID: PMC4552538 DOI: 10.14814/phy2.12463] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 06/24/2015] [Indexed: 11/24/2022] Open
Abstract
Sickle cell disease (SCD) is characterized by sudden onset of painful vaso-occlusive crises (VOC), which occur on top of the underlying chronic blood disorder. The mechanisms that trigger VOC remain elusive, but recent work suggests that autonomic dysfunction may be an important predisposing factor. Heart-rate variability has been employed in previous studies, but the derived indices have provided only limited univariate information about autonomic cardiovascular control in SCD. To circumvent this limitation, a time-varying modeling approach was applied to investigate the functional mechanisms relating blood pressure (BP) and respiration to heart rate and peripheral vascular resistance in healthy controls, untreated SCD subjects and SCD subjects undergoing chronic transfusion therapy. Measurements of respiration, heart rate, continuous noninvasive BP and peripheral vascular resistance were made before, during and after the application of cold face stimulation (CFS), which perturbs both the parasympathetic and sympathetic nervous systems. Cardiac baroreflex sensitivity estimated from the model was found to be impaired in nontransfused SCD subjects, but partially restored in SCD subjects undergoing transfusion therapy. Respiratory-cardiac coupling gain was decreased in SCD and remained unchanged by chronic transfusion. These results are consistent with autonomic dysfunction in the form of impaired parasympathetic control and sympathetic overactivity. As well, CFS led to a significant reduction in vascular resistance baroreflex sensitivity in the nontransfused SCD subjects but not in the other groups. This blunting of the baroreflex control of peripheral vascular resistance during elevated sympathetic drive could be a potential factor contributing to the triggering of VOC in SCD.
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Affiliation(s)
- Patjanaporn Chalacheva
- Department of Biomedical Engineering, Viterbi School of Engineering University of Southern California, Los Angeles, California, USA
| | - Roberta M Kato
- Department of Pediatrics, Children's Hospital of Los Angeles, Los Angeles, California, USA
| | - Suvimol Sangkatumvong
- Department of Biomedical Engineering, Viterbi School of Engineering University of Southern California, Los Angeles, California, USA
| | - Jon Detterich
- Department of Pediatrics, Children's Hospital of Los Angeles, Los Angeles, California, USA
| | - Adam Bush
- Department of Biomedical Engineering, Viterbi School of Engineering University of Southern California, Los Angeles, California, USA
| | - John C Wood
- Department of Pediatrics, Children's Hospital of Los Angeles, Los Angeles, California, USA
| | - Herbert Meiselman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Thomas D Coates
- Department of Pediatrics, Children's Hospital of Los Angeles, Los Angeles, California, USA
| | - Michael C K Khoo
- Department of Biomedical Engineering, Viterbi School of Engineering University of Southern California, Los Angeles, California, USA
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99
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Wood JC, Zhang P, Rienhoff H, Abi-Saab W, Neufeld EJ. Liver MRI is more precise than liver biopsy for assessing total body iron balance: a comparison of MRI relaxometry with simulated liver biopsy results. Magn Reson Imaging 2015; 33:761-7. [PMID: 25708262 DOI: 10.1016/j.mri.2015.02.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/14/2015] [Accepted: 02/16/2015] [Indexed: 02/06/2023]
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100
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Abstract
Iron overload is becoming an increasing problem as haemoglobinopathy patients gain greater access to good medical care and as therapies for myelodysplastic syndromes improve. Therapeutic options for iron chelation therapy have increased and many patients now receive combination therapies. However, optimal utilization of iron chelation therapy requires knowledge not only of the total body iron burden but the relative iron distribution among the different organs. The physiological basis for extrahepatic iron deposition is presented in order to help identify patients at highest risk for cardiac and endocrine complications. This manuscript reviews the current state of the art for monitoring global iron overload status as well as its compartmentalization. Plasma markers, computerized tomography, liver biopsy, magnetic susceptibility devices and magnetic resonance imaging (MRI) techniques are all discussed but MRI has come to dominate clinical practice. The potential impact of recent pancreatic and pituitary MRI studies on clinical practice are discussed as well as other works-in-progress. Clinical protocols are derived from experience in haemoglobinopathies but may provide useful guiding principles for other iron overload disorders, such as myelodysplastic syndromes.
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Affiliation(s)
- John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, CA, USA
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