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Vu C, Bush A, Borzage M, Choi S, Coloigner J, Farzad S, Chai Y, Coates TD, Wood JC. Brain BOLD and NIRS response to hyperoxic challenge in sickle cell disease and chronic anemias. Magn Reson Imaging 2023; 100:26-35. [PMID: 36924810 PMCID: PMC10171837 DOI: 10.1016/j.mri.2023.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/06/2023] [Accepted: 03/12/2023] [Indexed: 03/15/2023]
Abstract
PURPOSE Congenital anemias, including sickle cell anemia and thalassemia, are associated with cerebral tissue hypoxia and heightened stroke risks. Recent works in sickle cell disease mouse models have suggested that hyperoxia respiratory challenges can identify regions of the brain having chronic tissue hypoxia. Therefore, this work investigated differences in hyperoxic response and regional cerebral oxygenation between anemic and healthy subjects. METHODS A cohort of 38 sickle cell disease subjects (age 22 ± 8 years, female 39%), 25 non-sickle anemic subjects (age 25 ± 11 years, female 52%), and 31 healthy controls (age 25 ± 10 years, female 68%) were examined. A hyperoxic gas challenge was performed with concurrent acquisition of blood oxygen level-dependent (BOLD) MRI and near-infrared spectroscopy (NIRS). In addition to hyperoxia-induced changes in BOLD and NIRS, global measurements of cerebral blood flow, oxygen delivery, and cerebral metabolic rate of oxygen were obtained and compared between the three groups. RESULTS Regional BOLD changes were not able to identify brain regions of flow limitation in chronically anemic patients. Higher blood oxygen content and tissue oxygenation were observed during hyperoxia gas challenge. Both control and anemic groups demonstrated lower blood flow, oxygen delivery, and metabolic rate compared to baseline, but the oxygen metabolism in anemic subjects were abnormally low during hyperoxic exposure. CONCLUSION These results indicated that hyperoxic respiratory challenge could not be used to identify chronically ischemic brain. Furthermore, the low hyperoxia-induced metabolic rate suggested potential negative effects of prolonged oxygen therapy and required further studies to evaluate the risk for hyperoxia-induced oxygen toxicity and cerebral dysfunction.
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Affiliation(s)
- Chau Vu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States of America
| | - Adam Bush
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States of America; Department of Biomedical Engineering, University of Texas, Austin, TX, United States of America
| | - Matthew Borzage
- Division of Neonatology, Fetal and Neonatal Institute, Children's Hospital Los Angeles, Los Angeles, CA, United States of America; Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States of America
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States of America
| | - Julie Coloigner
- CIBORG Laboratory, Division of Radiology, Children's Hospital Los Angeles, Los Angeles, CA, United States of America; Univ Rennes, CNRS, Inria, Inserm, IRISA UMR 6074, Empenn ERL U 1228, F-35000 Rennes, France
| | - Shayan Farzad
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States of America
| | - Yaqiong Chai
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States of America
| | - Thomas D Coates
- Division of Hematology-Oncology, Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA, United States of America; Departments of Pediatrics and Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States of America
| | - John C Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States of America; Division of Cardiology, Departments of Pediatrics and Radiology, Children's Hospital Los Angeles, Los Angeles, CA, United States of America.
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Stumpo V, Sebök M, van Niftrik CHB, Seystahl K, Hainc N, Kulcsar Z, Weller M, Regli L, Fierstra J. Feasibility of glioblastoma tissue response mapping with physiologic BOLD imaging using precise oxygen and carbon dioxide challenge. MAGMA (NEW YORK, N.Y.) 2022; 35:29-44. [PMID: 34874499 DOI: 10.1007/s10334-021-00980-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/15/2021] [Accepted: 11/19/2021] [Indexed: 12/15/2022]
Abstract
OBJECTIVES Innovative physiologic MRI development focuses on depiction of heterogenous vascular and metabolic features in glioblastoma. For this feasibility study, we employed blood oxygenation level-dependent (BOLD) MRI with standardized and precise carbon dioxide (CO2) and oxygen (O2) modulation to investigate specific tumor tissue response patterns in patients with newly diagnosed glioblastoma. MATERIALS AND METHODS Seven newly diagnosed untreated patients with suspected glioblastoma were prospectively included to undergo a BOLD study with combined CO2 and O2 standardized protocol. %BOLD signal change/mmHg during hypercapnic, hypoxic, and hyperoxic stimulus was calculated in the whole brain, tumor lesion and segmented volumes of interest (VOI) [contrast-enhancing (CE) - tumor, necrosis and edema] to analyze their tissue response patterns. RESULTS Quantification of BOLD signal change after gas challenges can be used to identify specific responses to standardized stimuli in glioblastoma patients. Integration of this approach with automatic VOI segmentation grants improved characterization of tumor subzones and edema. Magnitude of BOLD signal change during the 3 stimuli can be visualized at voxel precision through color-coded maps overlayed onto whole brain and identified VOIs. CONCLUSIONS Our preliminary investigation shows good feasibility of BOLD with standardized and precise CO2 and O2 modulation as an emerging physiologic imaging technique to detail specific glioblastoma characteristics. The unique tissue response patterns generated can be further investigated to better detail glioblastoma lesions and gauge treatment response.
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Affiliation(s)
- Vittorio Stumpo
- Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland. .,Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Martina Sebök
- Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Christiaan Hendrik Bas van Niftrik
- Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Katharina Seystahl
- Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Nicolin Hainc
- Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Zsolt Kulcsar
- Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Michael Weller
- Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Luca Regli
- Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Jorn Fierstra
- Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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Vu C, Chai Y, Coloigner J, Nederveen AJ, Borzage M, Bush A, Wood JC. Quantitative perfusion mapping with induced transient hypoxia using BOLD MRI. Magn Reson Med 2020; 85:168-181. [PMID: 32767413 DOI: 10.1002/mrm.28422] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE Gadolinium-based dynamic susceptibility contrast (DSC) is commonly used to characterize blood flow in patients with stroke and brain tumors. Unfortunately, gadolinium contrast administration has been associated with adverse reactions and long-term accumulation in tissues. In this work, we propose an alternative deoxygenation-based DSC (dDSC) method that uses a transient hypoxia gas paradigm to deliver a bolus of paramagnetic deoxygenated hemoglobin to the cerebral vasculature for perfusion imaging. METHODS Through traditional DSC tracer kinetic modeling, the MR signal change induced by this hypoxic bolus can be used to generate regional perfusion maps of cerebral blood flow, cerebral blood volume, and mean transit time. This gas paradigm and blood-oxygen-level-dependent (BOLD)-MRI were performed concurrently on a cohort of 66 healthy and chronically anemic subjects (age 23.5 ± 9.7, female 64%). RESULTS Our results showed reasonable global and regional agreement between dDSC and other flow techniques, such as phase contrast and arterial spin labeling. CONCLUSION In this proof-of-concept study, we demonstrated the feasibility of using transient hypoxia to generate a contrast bolus that mimics the effect of gadolinium and yields reasonable perfusion estimates. Looking forward, optimization of the hypoxia boluses and measurement of the arterial-input function is necessary to improve the accuracy of dDSC. Additionally, a cross-validation study of dDSC and DSC in brain tumor and ischemic stroke subjects is warranted to evaluate the clinical diagnostic utility of this approach.
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Affiliation(s)
- Chau Vu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Yaqiong Chai
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.,Department of Radiology, CIBORG Laboratory, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Julie Coloigner
- Department of Radiology, CIBORG Laboratory, Children's Hospital Los Angeles, Los Angeles, CA, USA.,Univ Rennes, CNRS, Inria, Inserm, IRISA UMR 6074, Empenn ERL U 1228, Rennes, France
| | - Aart J Nederveen
- Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Matthew Borzage
- Division of Neonatology, Fetal and Neonatal Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA.,Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Adam Bush
- Department of Radiology, Stanford University, Stanford, CA, USA.,Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - John C Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.,Division of Cardiology, Department of Pediatrics and Radiology, Children's Hospital Los Angeles, Los Angeles, CA, USA
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Nejad-Davarani SP, Zakariaei N, Chen Y, Haacke EM, Hurst NJ, Salim Siddiqui M, Schultz LR, Snyder JM, Walbert T, Glide-Hurst CK. Rapid multicontrast brain imaging on a 0.35T MR-linac. Med Phys 2020; 47:4064-4076. [PMID: 32434276 DOI: 10.1002/mp.14251] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/03/2020] [Accepted: 05/13/2020] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Magnetic resonance-guided radiation therapy (MRgRT) has shown great promise for localization and real-time tumor monitoring. However, to date, quantitative imaging has been limited for low field MRgRT. This work benchmarks quantitative T1, R2*, and Proton Density (PD)mapping in a phantom on a 0.35 T MR-linac and implements a novel acquisition method, STrategically Acquired Gradient Echo (STAGE). To further validate STAGE in a clinical setting, a pilot study was undertaken in a cohort of brain tumor patients to elucidate opportunities for longitudinal functional imaging with an MR-linac in the brain. METHODS STAGE (two triple-echo gradient echo (GRE) acquisitions) was optimized for a 0.35T low-field MR-linac. Simulations were performed to choose two flip angles to optimize signal-to-noise ratio (SNR) and T1-mapping precision. Tradeoffs between SNR, scan time, and spatial resolution for whole-brain coverage were evaluated in healthy volunteers. Data were inputted into a STAGE processing pipeline to yield four qualitative images (T1-weighted, enhanced T1-weighted, proton-density (PD) weighted, and simulated FLuid-Attenuated Inversion Recovery (sFLAIR)), and three quantitative datasets (T1, PD, and R2*). A benchmarking ISMRM/NIST phantom consisting of vials with variable NiCl2 and MnCl2 concentrations was scanned using variable flip angles (VFA) (2-60 degrees) and inversion recovery (IR) methods at 0.35 T. STAGE and VFA T1 values of vials were compared to IR T1 values. As measures of agreement with reference values and repeatability, relative error (RE) and coefficient of variability (CV) were calculated, respectively, for quantitative MR values within the phantom vials (spheres). To demonstrate feasibility, longitudinal STAGE data (pretreatment, weekly, and ~ 2 months post-treatment) were acquired in an IRB-approved pilot study of brain tumor cases via the generation of temporal and differential quantitative MRI maps. RESULTS In the phantom, RE of measured VFA T1 and STAGE relative to IR reference values were 7.0 ± 2.5% and 9.5 ± 2.2% respectively. RE for the PD vials was 8.1 ± 6.8% and CV for phantom R2* measurements was 10.1 ± 9.9%. Simulations and volunteer experiments yielded final STAGE parameters of FA = 50°/10°, 1 × 1 × 3 mm3 resolution, TR = 40 ms, TE = 5/20/34 ms in 10 min (64 slices). In the pilot study of brain tumor patients, differential maps for R2* and T1 maps were sensitive to local tumor changes and appeared similar to 3 T follow-up MRI datasets. CONCLUSION Quantitative T1, R2*, and PD mapping are promising at 0.35 T agreeing well with reference data. STAGE phantom data offer quantitative representations comparable to traditional methods in a fraction of the acquisition time. Initial feasibility of implementing STAGE at 0.35 T in a patient brain tumor cohort suggests that detectable changes can be observed over time. With confirmation in a larger cohort, results may be implemented to identify areas of recurrence and facilitate adaptive radiation therapy.
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Affiliation(s)
- Siamak P Nejad-Davarani
- Department of Radiation Oncology, Henry Ford Cancer Institute, 2799 West Grand Blvd., Detroit, MI, 48202, USA
| | - Niloufar Zakariaei
- Department of Radiation Oncology, Henry Ford Cancer Institute, 2799 West Grand Blvd., Detroit, MI, 48202, USA
| | - Yongsheng Chen
- Department of Neurology, Wayne State University School of Medicine, 4201 St Antoine Blvd, 8C UHC, Detroit, MI, 48201, USA
| | - E Mark Haacke
- Department of Radiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.,The MRI Institute for Biomedical Research, 30200 Telegraph Rd, STE 104, Bingham Farms, Detroit, MI, 48025, USA
| | - Newton J Hurst
- Department of Radiation Oncology, Henry Ford Cancer Institute, 2799 West Grand Blvd., Detroit, MI, 48202, USA
| | - M Salim Siddiqui
- Department of Radiation Oncology, Henry Ford Cancer Institute, 2799 West Grand Blvd., Detroit, MI, 48202, USA
| | - Lonni R Schultz
- Department of Public Health Sciences, Henry Ford Health System, One Ford Place, Ste 3E, Detroit, MI, 48202, USA
| | - James M Snyder
- Departments of Neurosurgery and Neurology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, 48202, USA
| | - Tobias Walbert
- Departments of Neurosurgery and Neurology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, 48202, USA
| | - Carri K Glide-Hurst
- Department of Radiation Oncology, Henry Ford Cancer Institute, 2799 West Grand Blvd., Detroit, MI, 48202, USA
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Englund EK, Fernández-Seara MA, Rodríguez-Soto AE, Lee H, Rodgers ZB, Vidorreta M, Detre JA, Wehrli FW. Calibrated fMRI for dynamic mapping of CMRO 2 responses using MR-based measurements of whole-brain venous oxygen saturation. J Cereb Blood Flow Metab 2020; 40:1501-1516. [PMID: 31394960 PMCID: PMC7308517 DOI: 10.1177/0271678x19867276] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Functional MRI (fMRI) can identify active foci in response to stimuli through BOLD signal fluctuations, which represent a complex interplay between blood flow and cerebral metabolic rate of oxygen (CMRO2) changes. Calibrated fMRI can disentangle the underlying contributions, allowing quantification of the CMRO2 response. Here, whole-brain venous oxygen saturation (Yv) was computed alongside ASL-measured CBF and BOLD-weighted data to derive the calibration constant, M, using the proposed Yv-based calibration. Data were collected from 10 subjects at 3T with a three-part interleaved sequence comprising background-suppressed 3D-pCASL, 2D BOLD-weighted, and single-slice dual-echo GRE (to measure Yv via susceptometry-based oximetry) acquisitions while subjects breathed normocapnic/normoxic, hyperoxic, and hypercapnic gases, and during a motor task. M was computed via Yv-based calibration from both hypercapnia and hyperoxia stimulus data, and results were compared to conventional hypercapnia or hyperoxia calibration methods. Mean M in gray matter did not significantly differ between calibration methods, ranging from 8.5 ± 2.8% (conventional hyperoxia calibration) to 11.7 ± 4.5% (Yv-based calibration in response to hyperoxia), with hypercapnia-based M values between (p = 0.56). Relative CMRO2 changes from finger tapping were computed from each M map. CMRO2 increased by ∼20% in the motor cortex, and good agreement was observed between the conventional and proposed calibration methods.
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Affiliation(s)
- Erin K Englund
- Laboratory for Structural, Physiologic and Functional Imaging (LSPFI), Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Ana E Rodríguez-Soto
- Laboratory for Structural, Physiologic and Functional Imaging (LSPFI), Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Hyunyeol Lee
- Laboratory for Structural, Physiologic and Functional Imaging (LSPFI), Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Zachary B Rodgers
- Laboratory for Structural, Physiologic and Functional Imaging (LSPFI), Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.,Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marta Vidorreta
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA.,Siemens Healthineers, Madrid, Spain
| | - John A Detre
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Felix W Wehrli
- Laboratory for Structural, Physiologic and Functional Imaging (LSPFI), Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
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Lu CQ, Xu W, Zeng CH, Ge LY, Wang YC, Meng XP, Yu Q, Wu D, Ju S. Altered amplitude of low-frequency fluctuation in basal ganglia correlates to pulmonary ventilation function in COPD patients: A resting-state fMRI study. Brain Behav 2019; 9:e01336. [PMID: 31140760 PMCID: PMC6625472 DOI: 10.1002/brb3.1336] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/01/2019] [Accepted: 05/06/2019] [Indexed: 01/19/2023] Open
Abstract
INTRODUCTION Patients under chronic obstructive pulmonary disease (COPD) has been reported to be associated with a higher prevalence of cognitive impairment (CI). However, it is still largely unknown whether the aberrant resting-state spontaneous neuronal activity pattern reflected by the amplitude of low-frequency fluctuation (ALFF) analysis will be associated with the CI in COPD patients. MATERIALS A total of 28 COPD patients and 26 healthy controls were enrolled in this study. Of all the subjects, structural and functional MRI data, spirometry tests performance and neuropsychological assessments of different cognitive domains were collected. Voxel-based two-sample t tests were used to detect brain regions showing differences in the ALFF value between COPD patients and healthy controls. An additional fMRI runs with supplementary oxygen delivery were employed to explore the impact of elevated partial pressure of oxygen (PaO2 ) or moderate hyperoxia on ALFF in COPD patients and healthy controls respectively. RESULTS More extensive white matter lesion was detected in COPD patients. COPD patients exhibit decreased ALFF value in bilateral basal ganglia areas and right thalamus, and aberrant ALFF value is correlated with PaO2 and pulmonary ventilation function (FEV1%pred). COPD patients performed worse in the Digit Span Test (reverse), Digit Symbol Substitution Test, Trail-making test (A and B) than controls. After supplementary oxygen inhalation, the ALFF value of basal ganglia and right thalamus significantly increased in the controls, but not in the COPD patients. CONCLUSIONS COPD patients mainly exhibit impaired executive function but not long-term memory in cognitive function assessment. Aberrant ALFF alteration in the deep brain may be directly related to lower PaO2 in COPD patients.
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Affiliation(s)
- Chun-Qiang Lu
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Weiwei Xu
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Chu-Hui Zeng
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Lu-Yao Ge
- Department of Respirology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Yuan-Cheng Wang
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Xiang-Pan Meng
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Qian Yu
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Di Wu
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
| | - Shenghong Ju
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China
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Goldfarb JW, Hsu B, Cao JJ. Effects of supplemental oxygen on cardiovascular magnetic resonance water proton relaxation time constant measurements (T 1, T 2 and T 2*). Magn Reson Imaging 2019; 61:124-130. [PMID: 31082495 DOI: 10.1016/j.mri.2019.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/08/2019] [Accepted: 05/04/2019] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To study, the effects of supplemental oxygen on the measurement of native cardiovascular water proton relaxation time constants using commercially available protocols. METHODS T1, T2 and T2* relaxation time constant mapping were performed in twelve volunteers at 1.5 T breathing room air and supplemental oxygen supplied by nasal cannula and a non-rebreather mask. Regions-of-interest were drawn for quantitative measurements in the bloodpool of each ventricle and atria as well as septal myocardium. The effects of supplemental oxygen were investigated statistically using a mixed model analysis of variance. Intra- and inter-observer reproducibility were assessed using the Intraclass Correlation Coefficient and Coefficient of Variation. RESULTS Blood T1 relaxation time constants in the left ventricle (T1 change = -241.0 ms) and left atrium (T1 change = -247.0 ms) decreased significantly in every subject after oxygen inhalation with a non-rebreather mask (p < 0.001). No significant changes of T1 in the right side of the heart were detected after oxygen inhalation with the non-rebreather mask (p = 0.345). Oxygen inhalation with nasal cannula did not significantly change blood T1 in the study (p = 0.497). No significant changes in myocardial T1 (p = 0.390), T2 (p = 0.960) or T2* (p = 0.438) were observed with supplemental oxygen supplied by nasal cannula or the non-rebreather mask. Results were similar in mid-short-axis and horizontal long-axis acquisitions. CONCLUSION Supplemental oxygen does not affect myocardial relaxation time constant measurements with current protocols. On the other hand, blood T1 measurements with the inhalation of supplemental oxygen supplied by a non-rebreather mask change significantly and could affect myocardial tissue characterization if used for the calculation of extracellular volume. Additionally, current relaxation time constant mapping protocols do not reproducibly detect myocardial T1 changes with supplemental oxygen inhalation.
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Affiliation(s)
- James W Goldfarb
- Department of Research and Education, Saint Francis Hospital Roslyn, NY, USA.
| | - Brittany Hsu
- Department of Research and Education, Saint Francis Hospital Roslyn, NY, USA.
| | - Jie J Cao
- Department of Research and Education, Saint Francis Hospital Roslyn, NY, USA.
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Thiel S, Lettau F, Rejmer P, Rossi C, Haile S, Schwarz EI, Stöberl AS, Sievi NA, Boss A, Becker AS, Winklhofer S, Stradling JR, Kohler M. Effects of short-term continuous positive airway pressure withdrawal on cerebral vascular reactivity measured by blood oxygen level-dependent magnetic resonance imaging in obstructive sleep apnoea: a randomised controlled trial. Eur Respir J 2019; 53:13993003.01854-2018. [DOI: 10.1183/13993003.01854-2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/20/2018] [Indexed: 12/20/2022]
Abstract
Impaired cerebral vascular reactivity (CVR) increases long-term stroke risk. Obstructive sleep apnoea (OSA) is associated with peripheral vascular dysfunction and vascular events. The aim of this trial was to evaluate the effect of continuous positive airway pressure (CPAP) withdrawal on CVR.41 OSA patients (88% male, mean age 57±10 years) were randomised to either subtherapeutic or continuation of therapeutic CPAP. At baseline and after 2 weeks, patients underwent a sleep study and magnetic resonance imaging (MRI). CVR was estimated by quantifying the blood oxygen level-dependent (BOLD) MRI response to breathing stimuli.OSA did recur in the subtherapeutic CPAP group (mean treatment effect apnoea–hypopnoea index +38.0 events·h−1, 95% CI 24.2–52.0; p<0.001) but remained controlled in the therapeutic group. Although there was a significant increase in blood pressure upon CPAP withdrawal (mean treatment effect +9.37 mmHg, 95% CI 1.36–17.39; p=0.023), there was no significant effect of CPAP withdrawal on CVR assessedviaBOLD MRI under either hyperoxic or hypercapnic conditions.Short-term CPAP withdrawal did not result in statistically significant changes in CVR as assessed by functional MRI, despite the recurrence of OSA. We thus conclude that, unlike peripheral endothelial function, CVR is not affected by short-term CPAP withdrawal.
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Wengler K, Wang J, Serrano Sosa M, Gumus S, He A, Hussain S, Huang C, Tae Bae K, He X. Mapping hepatic blood oxygenation by quantitative BOLD (qBOLD) MRI. Magn Reson Med 2019; 81:3272-3282. [PMID: 30652357 DOI: 10.1002/mrm.27642] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/21/2018] [Accepted: 12/02/2018] [Indexed: 12/11/2022]
Abstract
PURPOSE Abnormalities in hepatic oxygen delivery and oxygen consumption may serve as a significant indicator of hepatic cellular dysfunction and may predict treatment response. However, conventional and oxygen-enhanced hepatic BOLD MRI can only provide semiquantitative assessment of hepatic oxygenation. METHODS A hepatic quantitative BOLD (qBOLD) model was proposed for noninvasive mapping of hepatic venous blood oxygen saturation (Yv ) and deoxygenated blood volume (DBV) in human subjects. The validity and the estimation bias of the proposed model were evaluated by Monte Carlo simulations. Eight healthy subjects were scanned after written consent with institutional review board approval. RESULTS Monte Carlo simulations demonstrated that the proposed single-compartment hepatic qBOLD model leads to significant deviation of the predicted T2 * decay profile from the simulated signal due to high hepatic blood volume fraction. Small relative estimation bias for hepatic Yv and significant overestimation for hepatic DBV were observed, which can be corrected by applying the calibration curves established from simulations. After correction, the mean hepatic Yv in human subjects was 56.8 ± 6.8%, and the mean hepatic DBV was 0.190 ± 0.035, consistent with measurements from other invasive approaches. Except in regions with significant vascular contamination, the maps for hepatic Yv and DBV were relatively homogenous. CONCLUSIONS With estimation bias correction, the hepatic qBOLD approach enables noninvasive mapping of hepatic blood volume and oxygenation in human subjects. The established protocol may be used to quantitatively assess hepatic tissue hypoxia in multiple liver diseases.
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Affiliation(s)
- Kenneth Wengler
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, New York
| | - Jinhong Wang
- Department of Medical Imaging, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Mario Serrano Sosa
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, New York
| | - Serter Gumus
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andrea He
- College of Letters and Science, University of Berkeley, Berkeley, California
| | - Shahid Hussain
- Department of Radiology, Stony Brook University, Stony Brook, New York, New York
| | - Chuan Huang
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, New York.,Department of Radiology, Stony Brook University, Stony Brook, New York, New York.,Department of Psychiatry, Stony Brook University, Stony Brook, New York, New York
| | - Kyong Tae Bae
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Xiang He
- Department of Radiology, Stony Brook University, Stony Brook, New York, New York
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Moosvi F, Baker JH, Yung A, Kozlowski P, Minchinton AI, Reinsberg SA. Fast and sensitive dynamic oxygen‐enhanced MRI with a cycling gas challenge and independent component analysis. Magn Reson Med 2018; 81:2514-2525. [DOI: 10.1002/mrm.27584] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 10/04/2018] [Accepted: 10/07/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Firas Moosvi
- Department of Physics & Astronomy University of British Columbia Vancouver Canada
| | - Jennifer H.E. Baker
- Radiation Biology Unit British Columbia Cancer Research Centre Vancouver Canada
| | - Andrew Yung
- UBC MRI Research Centre Life Sciences Centre Vancouver Canada
| | - Piotr Kozlowski
- UBC MRI Research Centre Life Sciences Centre Vancouver Canada
- Department of Radiology University of British Columbia Vancouver Canada
| | | | - Stefan A. Reinsberg
- Department of Physics & Astronomy University of British Columbia Vancouver Canada
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11
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Bright MG, Croal PL, Blockley NP, Bulte DP. Multiparametric measurement of cerebral physiology using calibrated fMRI. Neuroimage 2017; 187:128-144. [PMID: 29277404 DOI: 10.1016/j.neuroimage.2017.12.049] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 02/07/2023] Open
Abstract
The ultimate goal of calibrated fMRI is the quantitative imaging of oxygen metabolism (CMRO2), and this has been the focus of numerous methods and approaches. However, one underappreciated aspect of this quest is that in the drive to measure CMRO2, many other physiological parameters of interest are often acquired along the way. This can significantly increase the value of the dataset, providing greater information that is clinically relevant, or detail that can disambiguate the cause of signal variations. This can also be somewhat of a double-edged sword: calibrated fMRI experiments combine multiple parameters into a physiological model that requires multiple steps, thereby providing more opportunity for error propagation and increasing the noise and error of the final derived values. As with all measurements, there is a trade-off between imaging time, spatial resolution, coverage, and accuracy. In this review, we provide a brief overview of the benefits and pitfalls of extracting multiparametric measurements of cerebral physiology through calibrated fMRI experiments.
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Affiliation(s)
- Molly G Bright
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, UK; Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Paula L Croal
- IBME, Department of Engineering Science, University of Oxford, Oxford, UK
| | - Nicholas P Blockley
- FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Daniel P Bulte
- IBME, Department of Engineering Science, University of Oxford, Oxford, UK; FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
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12
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Abstract
Oxygen plays a fundamental role in functional magnetic resonance imaging (FMRI). Blood oxygenation level-dependent (BOLD) imaging is the foundation stone of all FMRI and is still the essential workhorse of the vast majority of FMRI procedures. Hemoglobin may provide the magnetic properties that allow the technique to work, but it is oxygen that allows the contrast to effectively be switched on or off, and it is oxygen that we are interested in tracking in order to observe the oxygen metabolism changes. In general the changes in venous oxygen saturation are observed in order to infer changes in the correlated mechanisms, which can include changes in cerebral blood flow, metabolism, and the fraction of inspired oxygen. By independently manipulating the fraction of inspired oxygen it is possible to alter the amount of dissolved oxygen in the plasma, the venous saturation, or even the blood flow. The effects that these changes have on the observed MRI signal can be either a help or a hindrance depending on how well the changes induced are understood. The administration of supplemental inspired oxygen is in a unique position to provide a flexible, noninvasive, inexpensive, patient-friendly addition to the MRI toolkit to enable investigations to look beyond statistics and regions of interest, and actually produce calibrated, targeted measurements of blood flow, metabolism or pathology.
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Affiliation(s)
- Daniel Bulte
- FMRIB Centre, John Radcliffe Hospital, University of Oxford, Oxford, UK.
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Quantitative T2, T2*, and T2' MR imaging in patients with ischemic leukoaraiosis might detect microstructural changes and cortical hypoxia. Neuroradiology 2015; 57:1023-30. [PMID: 26227168 DOI: 10.1007/s00234-015-1565-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/13/2015] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Quantitative MRI with T2, T2*, and T2' mapping has been shown to non-invasively depict microstructural changes (T2) and oxygenation status (T2* and T2') that are invisible on conventional MRI. Therefore, we aimed to assess whether T2 and T2' quantification detects cerebral (micro-)structural damage and chronic hypoxia in lesions and in normal appearing white matter (WM) and gray matter (GM) of patients with ischemic leukoaraiosis (IL). Measurements were complemented by the assessment of the cerebral blood flow (CBF) and the degree of GM and WM atrophy. METHODS Eighteen patients with IL and 18 age-matched healthy controls were included. High-resolution, motion-corrected T2, T2*, and T2' mapping, CBF mapping (pulsed arterial spin labeling, PASL), and segmentation of GM and WM were used to depict specific changes in both groups. All parameters were compared between patients and healthy controls, using t testing. Values of p < 0.05 were accepted as statistically significant. RESULTS Patients showed significantly increased T2 in lesions (p < 0.01) and in unaffected WM (p = 0.045) as well as significantly increased T2* in lesions (p = 0.003). A significant decrease of T2' was detected in patients in unaffected WM (p = 0.027), while no T2' changes were observed in GM (p = 0.13). Both unaffected WM and GM were significantly decreased in volume in the patient-group (p < 0.01). No differences of PASL-based CBF could be shown. CONCLUSION Non-invasive quantitative MRI with T2, T2*, and T2' mapping might be used to detect subtle structural and metabolic changes in IL. Assessing the grade of microstructural damage and hypoxia might be helpful to monitor disease progression and to perform risk assessment.
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14
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Gotzamanis G, Kocian R, Özbay PS, Redle M, Kollias S, Eberhardt C, Boss A, Nanz D, Rossi C. In vivo quantification of cerebral r2*-response to graded hyperoxia at 3 tesla. J Clin Imaging Sci 2015; 5:1. [PMID: 25806136 PMCID: PMC4322383 DOI: 10.4103/2156-7514.150439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 01/22/2015] [Indexed: 11/13/2022] Open
Abstract
Objectives: This study aims to quantify the response of the transverse relaxation rate of the magnetic resonance (MR) signal of the cerebral tissue in healthy volunteers to the administration of air with step-wise increasing percentage of oxygen. Materials and Methods: The transverse relaxation rate (R2*) of the MR signal was quantified in seven volunteers under respiratory intake of normobaric gas mixtures containing 21, 50, 75, and 100% oxygen, respectively. End-tidal breath composition, arterial blood saturation (SaO2), and heart pulse rate were monitored during the challenge. R2* maps were computed from multi-echo, gradient-echo magnetic resonance imaging (MRI) data, acquired at 3.0T. The average values in the segmented white matter (WM) and gray matter (GM) were tested by the analysis of variance (ANOVA), with Bonferroni post-hoc correction. The GM R2*-reactivity to hyperoxia was modeled using the Hill's equation. Results: Graded hyperoxia resulted in a progressive and significant (P < 0.05) decrease of the R2* in GM. Under normoxia the GM-R2* was 17.2 ± 1.1 s-1. At 75% O2 supply, the R2* had reached a saturation level, with 16.4 ± 0.7 s-1 (P = 0.02), without a significant further decrease for 100% O2. The R2*-response of GM correlated positively with CO2 partial pressure (R = 0.69 ± 0.19) and negatively with SaO2 (R = -0.74 ± 0.17). The WM showed a similar progressive, but non-significant, decrease in the relaxation rates, with an increase in oxygen intake (P = 0.055). The Hill's model predicted a maximum R2* response of the GM, of 3.5%, with half the maximum at 68% oxygen concentration. Conclusions: The GM-R2* responds to hyperoxia in a concentration-dependent manner, suggesting that monitoring and modeling of the R2*-response may provide new oxygenation biomarkers for tumor therapy or assessment of cerebrovascular reactivity in patients.
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Affiliation(s)
- Grigorios Gotzamanis
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland ; Klinikum Dritter Orden, Center for Radiology and Nuclear Medicine, Munich, Germany
| | - Roman Kocian
- Department of Anesthesiology, University Hospital of Zurich, Zurich, Switzerland
| | - Pinar S Özbay
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland ; Institute for Biomedical Engineering, Eidgenössische Technische Hochschule (ETH), Zurich, Switzerland
| | - Manuel Redle
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland
| | - Spyridon Kollias
- Department of Neuroradiology, University Hospital of Zurich, Zurich, Switzerland
| | - Christian Eberhardt
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland
| | - Andreas Boss
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland
| | - Daniel Nanz
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland
| | - Cristina Rossi
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland
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15
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Croal PL, Hall EL, Driver ID, Brookes MJ, Gowland PA, Francis ST. The effect of isocapnic hyperoxia on neurophysiology as measured with MRI and MEG. Neuroimage 2015; 105:323-31. [DOI: 10.1016/j.neuroimage.2014.10.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 08/27/2014] [Accepted: 10/14/2014] [Indexed: 10/24/2022] Open
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Abstract
We studied the effect of oxygen inhalation during resting state functional MRI scanning in healthy control individuals. We hypothesized that resting state networks would be modified under hyperoxic conditions. Thirty-four normal volunteers were recruited for this study. All participants were scanned twice: once while breathing atmospheric air and once under hyperoxic conditions in a randomized order. Hyperoxic conditions were produced by administering 100% O2. Blood oxygen level-dependent T2* scans were obtained for each of the scans. Resting state networks were extracted using independent component analysis. A paired t-test showed that the resting state networks scans (default mode network, attention network and executive network) acquired under hyperoxic conditions had significantly higher Z-scores than scans performed under atmospheric air. Spectral analysis of the time-course signal in these networks also showed a difference in the total power of low frequencies between the two conditions. These results were reversed in the visual network. Clinical or research applications of oxygen-enhanced MRI need to take into account the modularly effects that hyperoxia exerts on the networks resting state functional MRI.
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17
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Mehemed TM, Fushimi Y, Okada T, Yamamoto A, Kanagaki M, Kido A, Fujimoto K, Sakashita N, Togashi K. Dynamic oxygen-enhanced MRI of cerebrospinal fluid. PLoS One 2014; 9:e100723. [PMID: 24956198 PMCID: PMC4067336 DOI: 10.1371/journal.pone.0100723] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 05/29/2014] [Indexed: 11/18/2022] Open
Abstract
Oxygen causes an increase in the longitudinal relaxation rate of tissues through its T1-shortening effect owing to its paramagnetic properties. Due to such effects, MRI has been used to study oxygen-related signal intensity changes in various body parts including cerebrospinal fluid (CSF) space. Oxygen enhancement of CSF has been mainly studied using MRI sequences with relatively longer time resolution such as FLAIR, and T1 value calculation. In this study, fifteen healthy volunteers were scanned using fast advanced spin echo MRI sequence with and without inversion recovery pulse in order to dynamically track oxygen enhancement of CSF. We also focused on the differences of oxygen enhancement at sulcal and ventricular CSF. Our results revealed that CSF signal after administration of oxygen shows rapid signal increase in both sulcal CSF and ventricular CSF on both sequences, with statistically significant predominant increase in sulcal CSF compared with ventricular CSF. CSF is traditionally thought to mainly form from the choroid plexus in the ventricles and is absorbed at the arachnoid villi, however, it is also believed that cerebral arterioles contribute to the production and absorption of CSF, and controversy remains in terms of the precise mechanism. Our results demonstrated rapid oxygen enhancement in sulcal CSF, which may suggest inhaled oxygen may diffuse into sulcal CSF space rapidly probably due to the abundance of pial arterioles on the brain sulci.
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Affiliation(s)
- Taha M. Mehemed
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yasutaka Fushimi
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
- * E-mail:
| | - Tomohisa Okada
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akira Yamamoto
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Mitsunori Kanagaki
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Aki Kido
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Koji Fujimoto
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Naotaka Sakashita
- Toshiba Medical Systems Corporation, MRI Systems Development Department Otawara-shi, Tochigi, Japan
| | - Kaori Togashi
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
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18
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Impact of gas delivery systems on imaging studies of human cerebral blood flow. Radiol Res Pract 2013; 2013:694803. [PMID: 24392225 PMCID: PMC3874307 DOI: 10.1155/2013/694803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 11/08/2013] [Accepted: 11/13/2013] [Indexed: 11/30/2022] Open
Abstract
Purpose. To compare a semiopen breathing circuit with a non-rebreathing (Hudson mask) for MRI experiments involving gas delivery. Methods and Materials. Cerebral blood flow (CBF) was measured by quantitative phase contrast angiography of the internal carotid and basilar arteries in 18 volunteers (20–31 years). In 8 subjects, gases were delivered via a standard non-rebreathing (Hudson mask). In 10 subjects, gases were delivered using a modified “Mapleson A” semiopen anesthetic gas circuit and mouthpiece. All subjects were given 100% O2, medical air, and carbogen gas (95% O2 and 5% CO2) delivered at 15 L/min in a random order. Results. The Hudson mask group showed significant increases in CBF in response to increased FiCO2 compared to air (+9.8%). A small nonsignificant reduction in CBF (−2.4%) was seen in response to increased inspired concentrations of oxygen (FiO2). The Mapleson A group showed significantly larger changes in CBF in response to both increased inspired concentrations of carbon dioxide (FiCO2) (+32.2%, P < 0.05) and FiO2 (−14.6%, P < 0.01). Conclusions. The use of an anaesthetic gas delivery circuit avoids entrainment of room air and rebreathing effects that may otherwise adversely affect the experimental results.
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19
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Liu Z, Liao H, Yin J, Li Y. Using R2* values to evaluate brain tumours on magnetic resonance imaging: Preliminary results. Eur Radiol 2013; 24:693-702. [DOI: 10.1007/s00330-013-3057-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 10/08/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022]
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20
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Huang CH, Chen CCV, Siow TY, Hsu SHS, Hsu YH, Jaw FS, Chang C. High-resolution structural and functional assessments of cerebral microvasculature using 3D Gas ΔR2*-mMRA. PLoS One 2013; 8:e78186. [PMID: 24223773 PMCID: PMC3817180 DOI: 10.1371/journal.pone.0078186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 09/09/2013] [Indexed: 11/19/2022] Open
Abstract
The ability to evaluate the cerebral microvascular structure and function is crucial for investigating pathological processes in brain disorders. Previous angiographic methods based on blood oxygen level-dependent (BOLD) contrast offer appropriate visualization of the cerebral vasculature, but these methods remain to be optimized in order to extract more comprehensive information. This study aimed to integrate the advantages of BOLD MRI in both structural and functional vascular assessments. The BOLD contrast was manipulated by a carbogen challenge, and signal changes in gradient-echo images were computed to generate ΔR2* maps. Simultaneously, a functional index representing the regional cerebral blood volume was derived by normalizing the ΔR2* values of a given region to those of vein-filled voxels of the sinus. This method is named 3D gas ΔR2*-mMRA (microscopic MRA). The advantages of using 3D gas ΔR2*-mMRA to observe the microvasculature include the ability to distinguish air-tissue interfaces, a high vessel-to-tissue contrast, and not being affected by damage to the blood-brain barrier. A stroke model was used to demonstrate the ability of 3D gas ΔR2*-mMRA to provide information about poststroke revascularization at 3 days after reperfusion. However, this technique has some limitations that cannot be overcome and hence should be considered when it is applied, such as magnifying vessel sizes and predominantly revealing venous vessels.
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Affiliation(s)
- Chien-Hsiang Huang
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | | | - Tiing-Yee Siow
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | | | - Yi-Hua Hsu
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Fu-Shan Jaw
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chen Chang
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
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21
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Abstract
Oxygen-enhanced MRI has been shown to be a viable alternative to hyperpolarized gases for pulmonary imaging. The changes in the relaxation times due to hyperoxic conditions in the blood pool induced by inhalation of pure oxygen have produced sufficient signal changes for imaging applications. This is a safe and low-cost alternative for contrast-enhanced imaging. The application of oxygen-enhanced MRI in brain imaging has been much less studied. In this study, we investigated the changes in the relaxation times in the brain due to inhalation of pure oxygen in a rodent model. We also assessed the effects of reduced blood flow due to hyperoxic conditions. Despite the reduced blood flow, significant changes in T1, T2, and T2* relaxation times were detected. We conclude that oxygen-enhanced MRI can be used in rodent models of disease.
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22
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Artzi M, Aizenstein O, Abramovitch R, Bashat DB. MRI multiparametric hemodynamic characterization of the normal brain. Neuroscience 2013; 240:269-76. [PMID: 23500143 DOI: 10.1016/j.neuroscience.2013.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 03/03/2013] [Accepted: 03/05/2013] [Indexed: 02/04/2023]
Abstract
Characterization of the brain's vascular system is of major clinical importance in the assessment of patients with cerebrovascular disease. The aim of this study was to characterize brain hemodynamics using multiparametric methods and to obtain reference values from the healthy brain. A multimodal magnetic resonance imaging (MRI) study was performed in twenty healthy subjects, including dynamic susceptibility contrast imaging and blood oxygen level dependence (BOLD) during hypercapnia and carbogen challenges. Brain tissues were defined using unsupervised cluster analysis based on these three methods, and several hemodynamic parameters were calculated for gray matter (GM), white matter (WM), blood vessels and dura (BVD); the three main vascular territories within the GM; and arteries and veins defined within the BVD cluster. The carbogen challenge produced a BOLD signal twice as high as the hypercapnia challenge, in all brain tissues. The three brain tissues differed significantly from each other in their hemodynamic characteristics, supporting the graded vascularity of the tissues, with BVD>GM>WM. Within the GM cluster, a significant delay of ∼1.2 s of the bolus arrival time was detected within the posterior cerebral artery territory relative to the middle and anterior cerebral artery territories. No differences were detected between right and left middle cerebral artery territories for all hemodynamic parameters. Within the BVD cluster, a significant delay of ∼1.9 s of the bolus arrival time was detected within the veins relative to the arteries. This parameter enabled to differentiate between the various blood vessels, including arteries, veins and choroid plexus. This study provides reference values for several hemodynamic parameters, obtained from healthy brains, and may be clinically important in the assessment of patients with various vascular pathologies.
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Affiliation(s)
- M Artzi
- The Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
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23
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Huen I, Morris DM, Wright C, Parker GJM, Sibley CP, Johnstone ED, Naish JH. R1 and R2 * changes in the human placenta in response to maternal oxygen challenge. Magn Reson Med 2012; 70:1427-33. [PMID: 23280967 DOI: 10.1002/mrm.24581] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 11/09/2012] [Accepted: 11/11/2012] [Indexed: 11/05/2022]
Abstract
PURPOSE Pregnancy complications such as preeclampsia and fetal growth restriction are sometimes thought to be caused by placental abnormalities associated with reduced oxygenation. Oxygen-enhanced MRI (R1 contrast) and BOLD MRI (R2 * contrast) have the potential to noninvasively investigate this oxygen environment at a range of gestational ages. METHODS Scanning was carried out at 1.5 T under maternal air and oxygen breathing in a single placental slice in 14 healthy pregnant subjects of gestational ages 21-37 weeks. We report R1 changes using a respiratory-triggered inversion recovery-turbo spin-echo sequence, which is sensitive to changes in PO2 , and R2 * changes using a breathhold multiple gradient-recalled echo sequence sensitive to changes in oxygen saturation. RESULTS Significant R1 increases (P < 0.005, paired t-test) and R2 * decreases (P < 0.0001, paired t-test) between air and oxygen breathing were demonstrated. ΔR1 decreased with gestational age (P < 0.0005, r = -0.835, Pearson correlation test). No significant effect of gestational age on R2 * change was observed. CONCLUSION The results demonstrate the feasibility of non-invasive investigation of placental oxygenation using MRI and the sensitivity of R1 oxygen-enhanced MRI to gestational age. The techniques have the potential to provide unique noninvasive biomarkers in compromised pregnancies.
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Affiliation(s)
- Isaac Huen
- Centre for Imaging Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK; The University of Manchester Biomedical Imaging Institute, University of Manchester, Manchester, UK
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24
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Wagner M, Jurcoane A, Volz S, Magerkurth J, Zanella FE, Neumann-Haefelin T, Deichmann R, Singer OC, Hattingen E. Age-related changes of cerebral autoregulation: new insights with quantitative T2'-mapping and pulsed arterial spin-labeling MR imaging. AJNR Am J Neuroradiol 2012; 33:2081-7. [PMID: 22700750 DOI: 10.3174/ajnr.a3138] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Cerebral perfusion and O(2) metabolism are affected by physiologic age-related changes. High-resolution motion-corrected quantitative T2'-imaging and PASL were used to evaluate differences in deoxygenated hemoglobin and CBF of the gray matter between young and elderly healthy subjects. Further combined T2'-imaging and PASL were investigated breathing room air and 100% O(2) to evaluate age-related changes in cerebral autoregulation. MATERIALS AND METHODS Twenty-two healthy volunteers 60-88 years of age were studied. Two scans of high-resolution motion-corrected T2'-imaging and PASL-MR imaging were obtained while subjects were either breathing room air or breathing 100% O(2). Manual and automated regions of interest were placed in the cerebral GM to extract values from the corresponding maps. Results were compared with those of a group of young healthy subjects previously scanned with the identical protocol as that used in the present study. RESULTS There was a significant decrease of cortical CBF (P < .001) and cortical T2' values (P < .001) between young and elderly healthy subjects. In both groups, T2' remained unchanged under hyperoxia compared with normoxia. Only in the younger but not in the elderly group could a significant (P = .02) hyperoxic-induced decrease of the CBF be shown. CONCLUSIONS T2'-mapping and PASL in the cerebral cortex of healthy subjects revealed a significant decrease of deoxygenated hemoglobin and of CBF with age. The constant deoxyHb level breathing 100% O(2) compared with normoxia in young and elderly GM suggests an age-appropriate cerebral autoregulation. At the younger age, hyperoxic-induced CBF decrease may protect the brain from hyperoxemia.
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Affiliation(s)
- M Wagner
- Institute of Neuroradiology, Goethe University Frankfurt am Main, Frankfurt am Main, Germany.
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25
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Hemodynamic response imaging: a potential tool for the assessment of angiogenesis in brain tumors. PLoS One 2012; 7:e49416. [PMID: 23209575 PMCID: PMC3507885 DOI: 10.1371/journal.pone.0049416] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/10/2012] [Indexed: 11/29/2022] Open
Abstract
Blood oxygenation level dependence (BOLD) imaging under either hypercapnia or hyperoxia has been used to study neuronal activation and for assessment of various brain pathologies. We evaluated the benefit of a combined protocol of BOLD imaging during both hyperoxic and hypercapnic challenges (termed hemodynamic response imaging (HRI)). Nineteen healthy controls and seven patients with primary brain tumors were included: six with glioblastoma (two newly diagnosed and four with recurrent tumors) and one with atypical-meningioma. Maps of percent signal intensity changes (ΔS) during hyperoxia (carbogen; 95%O2+5%CO2) and hypercapnia (95%air+5%CO2) challenges and vascular reactivity mismatch maps (VRM; voxels that responded to carbogen with reduced/absent response to CO2) were calculated. VRM values were measured in white matter (WM) and gray matter (GM) areas of healthy subjects and used as threshold values in patients. Significantly higher response to carbogen was detected in healthy subjects, compared to hypercapnia, with a GM/WM ratio of 3.8 during both challenges. In patients with newly diagnosed/treatment-naive tumors (n = 3), increased response to carbogen was detected with substantially increased VRM response (compared to threshold values) within and around the tumors. In patients with recurrent tumors, reduced/absent response during both challenges was demonstrated. An additional finding in 2 of 4 patients with recurrent glioblastoma was a negative response during carbogen, distant from tumor location, which may indicate steal effect. In conclusion, the HRI method enables the assessment of blood vessel functionality and reactivity. Reference values from healthy subjects are presented and preliminary results demonstrate the potential of this method to complement perfusion imaging for the detection and follow up of angiogenesis in patients with brain tumors.
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26
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Wagner M, Magerkurth J, Volz S, Jurcoane A, Singer OC, Neumann‐Haefelin T, Zanella FE, Deichmann R, Hattingen E. T2′‐ and PASL‐based perfusion mapping at 3 Tesla: influence of oxygen‐ventilation on cerebral autoregulation. J Magn Reson Imaging 2012; 36:1347-52. [DOI: 10.1002/jmri.23777] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 07/20/2012] [Indexed: 11/07/2022] Open
Affiliation(s)
- Marlies Wagner
- Institute of Neuroradiology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Jörg Magerkurth
- Institute of Neuroradiology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Steffen Volz
- Brain Imaging Center, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Alina Jurcoane
- Institute of Neuroradiology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Oliver C. Singer
- Department of Neurology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Tobias Neumann‐Haefelin
- Department of Neurology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Friedhelm E. Zanella
- Institute of Neuroradiology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Ralf Deichmann
- Brain Imaging Center, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Elke Hattingen
- Institute of Neuroradiology, University Hospital, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
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Christen T, Bolar DS, Zaharchuk G. Imaging brain oxygenation with MRI using blood oxygenation approaches: methods, validation, and clinical applications. AJNR Am J Neuroradiol 2012; 34:1113-23. [PMID: 22859287 DOI: 10.3174/ajnr.a3070] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
SUMMARY In many pathophysiologic situations, including brain neoplasms, neurodegenerative disease, and chronic and acute ischemia, an imbalance exists between oxygen tissue consumption and delivery. Furthermore, oxygenation changes following a stress challenge, such as with carbogen gas or acetazolamide, can yield information about cerebrovascular reactivity. The unique sensitivity of the BOLD effect to the presence of deoxyhemoglobin has led to its widespread use in the field of cognitive neurosciences. However, the high spatial and temporal resolution afforded by BOLD imaging does not need to be limited to the study of healthy brains. While the complex relationship between the MR imaging signal and tissue oxygenation hinders a direct approach, many different methods have been developed during the past decade to obtain specific oxygenation measurements. These include qBOLD, phase- and susceptibility-based imaging, and intravascular T2-based approaches. The aim of this review is to give an overview of the theoretic basis of these methods as well as their application to measure oxygenation in both healthy subjects and those with disease.
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Affiliation(s)
- T Christen
- Department of Radiology, Stanford University, Stanford, CA 94305-5488, USA
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Rossi C, Boss A, Donati OF, Luechinger R, Kollias SS, Valavanis A, Hodler J, Nanz D. Manipulation of cortical gray matter oxygenation by hyperoxic respiratory challenge: field dependence of R(2) * and MR signal response. NMR IN BIOMEDICINE 2012; 25:1007-1014. [PMID: 22311278 DOI: 10.1002/nbm.2775] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/14/2011] [Accepted: 12/12/2011] [Indexed: 05/31/2023]
Abstract
The aim of this study was to quantitatively assess the field strength dependence of the transverse relaxation rate (R(2) *) change in cortical gray matter induced by hyperoxia and hyperoxic hypercapnia versus normoxia in an intra-individual comparison of young healthy volunteers. Medical air (21% O(2) ), pure oxygen and carbogen (95% O(2) , 5% CO(2) ) were alternatively administered in a block-design temporal pattern to induce normoxia, hyperoxia and hyperoxic hypercapnia, respectively. Local R(2) * values were determined from three-dimensional, multiple, radiofrequency-spoiled, fast field echo data acquired at 1.5, 3 and 7 T. Image quality was good at all field strengths. Under normoxia, the mean gray matter R(2) * values were 13.3 ± 2.7 s(-1) (1.5 T), 16.9 ± 0.9 s(-1) (3 T) and 29.0 ± 2.6 s(-1) (7 T). Both hyperoxic gases induced relaxation rate decreases ΔR(2) *, whose magnitudes increased quadratically with the field strength [carbogen: -0.69 ± 0.20 s(-1) (1.5 T), -1.49 ± 0.49 s(-1) (3 T), -5.64 ± 0.67 s(-1) (7 T); oxygen: -0.39 ± 0.20 s(-1) (1.5 T), -0.78 ± 0.48 s(-1) (3 T), -3.86 ± 1.00 s(-1) (7 T)]. Carbogen produced larger R(2) * changes than oxygen at all field strengths. The relative change ΔR(2) */R(2) * also increased with the field strength with a power between 1 and 2 for both carbogen and oxygen. The statistical significance of the R(2) * response improved with increasing B(0) and was higher for carbogen than for oxygen. For a sequence with pure T(2) * weighting of the signal response to respiratory challenge, the results suggested a maximum carbogen-induced signal difference of 19.3% of the baseline signal at 7 T and TE = 38 ms, but a maximum oxygen-induced signal difference of only 3.0% at 1.5 T and TE = 76 ms. For 3 T, maximum signal changes of 4.7% (oxygen) and 8.9% (carbogen) were computed. In conclusion, the R(2) * response to hyperoxic respiratory challenge was stronger for carbogen than for oxygen, and increased quadratically with the static magnetic field strength for both challenges, which highlights the importance of high field strengths for future studies aimed at probing oxygen physiology in clinical settings.
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Affiliation(s)
- Cristina Rossi
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland.
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Kalamangalam GP, Nelson JT, Ellmore TM, Narayana PA. Oxygen-enhanced MRI in temporal lobe epilepsy: diagnosis and lateralization. Epilepsy Res 2011; 98:50-61. [PMID: 21917423 DOI: 10.1016/j.eplepsyres.2011.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Revised: 08/13/2011] [Accepted: 08/20/2011] [Indexed: 10/17/2022]
Abstract
We explored the diagnostic value of oxygen-enhanced MRI, a novel technique for measuring regional brain metabolism, in a set of normal adult volunteers and temporal lobe epilepsy patients. Eight right-handed adult normal volunteers and ten right-handed patients with temporal lobe epilepsy were studied. Six patients had lesions concordant with their epilepsy on high-resolution (3T) structural MRI. Four patients were nonlesional. Hyperoxia (oxygen enhancement, OE) was carried out by administering 100% O(2) in epochs by mask or cannula interleaved with breathing of normal atmospheric air. The T2* (blood oxygen level dependent, BOLD) signal was recorded in continuously acquired echo-planar images. Data from nine temporal lobe subregions were subjected to spectral analysis and statistical testing. OE resulted in unambiguous concordant positive T2* signal change in all subjects. Analysis of the distribution of spectral power within the temporal lobe revealed a significant (p<0.025, one-sided) group difference between normals and epilepsy patients, with seven patients exhibiting large deviations from normalcy that lateralized their disease. Two such patients had nonlesional MRIs. Oxygen-enhanced MRI is a promising metabolic imaging modality for the diagnosis and lateralization of oxidative metabolic derangement associated with lesional and nonlesional temporal lobe epilepsy.
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Pilkinton DT, Hiraki T, Detre JA, Greenberg JH, Reddy R. Absolute cerebral blood flow quantification with pulsed arterial spin labeling during hyperoxia corrected with the simultaneous measurement of the longitudinal relaxation time of arterial blood. Magn Reson Med 2011; 67:1556-65. [PMID: 22135087 DOI: 10.1002/mrm.23137] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 06/06/2011] [Accepted: 07/13/2011] [Indexed: 11/06/2022]
Abstract
Quantitative arterial spin labeling (ASL) estimates of cerebral blood flow (CBF) during oxygen inhalation are important in several contexts, including functional experiments calibrated with hyperoxia and studies investigating the effect of hyperoxia on regional CBF. However, ASL measurements of CBF during hyperoxia are confounded by the reduction in the longitudinal relaxation time of arterial blood (T(1a) ) from paramagnetic molecular oxygen dissolved in blood plasma. The aim of this study is to accurately quantify the effect of arbitrary levels of hyperoxia on T(1a) and correct ASL measurements of CBF during hyperoxia on a per-subject basis. To mitigate artifacts, including the inflow of fresh spins, partial voluming, pulsatility, and motion, a pulsed ASL approach was implemented for in vivo measurements of T(1a) in the rat brain at 3 Tesla. After accounting for the effect of deoxyhemoglobin dilution, the relaxivity of oxygen on blood was found to closely match phantom measurements. The results of this study suggest that the measured ASL signal changes are dominated by reductions in T(1a) for brief hyperoxic inhalation epochs, while the physiologic effects of oxygen on the vasculature account for most of the measured reduction in CBF for longer hyperoxic exposures.
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Affiliation(s)
- David T Pilkinton
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Pilkinton DT, Gaddam SR, Reddy R. Characterization of paramagnetic effects of molecular oxygen on blood oxygenation level-dependent-modulated hyperoxic contrast studies of the human brain. Magn Reson Med 2011; 66:794-801. [PMID: 21608026 DOI: 10.1002/mrm.22870] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 12/22/2010] [Accepted: 01/17/2011] [Indexed: 11/08/2022]
Abstract
In hyperoxic contrast studies modulated by the blood oxygenation level-dependent effect, it is often assumed that hyperoxia is a purely intravascular, positive contrast agent in T 2*-weighted images, and the effects that are not due to blood oxygenation level-dependent contrast are small enough to be ignored. In this study, this assumption is re-evaluated and non-blood oxygenation level-dependent effects in T 2*-weighted hyperoxic contrast studies of the human brain were characterized. We observed significant negative signal changes in T 2*-weighted images in the frontal lobes; B(0) maps suggest that this effect was primarily due to increased intravoxel dephasing from increased static field inhomogeneity due to susceptibility changes from oxygen in and around the upper airway. These static field effects were shown to scale with magnetic field strength. Signal changes observed around the brain periphery and in the ventricles suggest the effect of image distortions from oxygen-induced bulk B(0) shifts, along with a possible contribution from decreased T 2* due to oxygen dissolved in the cerebrospinal fluid. Reducing the concentration of inhaled oxygen was shown to mitigate negative contrast of molecular oxygen due to these effects, while still maintaining sufficient blood oxygenation level-dependent contrast to produce accurate measurements of cerebral blood volume.
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Affiliation(s)
- David T Pilkinton
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Reliability and convergent validity of different BOLD MRI frameworks for data acquisition in experimental arthritis. Acad Radiol 2011; 18:615-25. [PMID: 21419665 DOI: 10.1016/j.acra.2010.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 11/25/2010] [Accepted: 12/09/2010] [Indexed: 11/20/2022]
Abstract
RATIONALE AND OBJECTIVES The clinimetric properties of blood oxygen level‒dependent (BOLD) magnetic resonance imaging (MRI) for assessment of musculoskeletal changes have been poorly investigated. The study objectives were to assess the interframework reliability of data acquisition of BOLD MRI and to test its convergent validity in chronic arthritis in a rabbit model of inflammatory arthritis as compared with corresponding clinical and laboratory measures. MATERIALS AND METHODS One of the knees of 12 New Zealand male white rabbits was injected with a 1% carrageenin solution, and the contralateral (control) one was not. Twelve rabbits were euthanized on day 28 of arthritis (chronic arthritis). Clinical (joint diameters), laboratory (serum amyloid A concentration), and BOLD MRI measurements were obtained on days 0, 1, and 28 of arthritis. Twenty paradigms of data acquisition and analysis were applied. RESULTS The most reliable MRI parameters set, regardless of threshold values used for data analysis, was spiral technique (level 1), 40 ms of echo time (level 2), 60 seconds of on_ and off_ paradigm (level 3) and carbogen mixture of gases (95% O2 + 5% CO2) (level 4). With regard to construct validity, BOLD imaging correlated moderately (r = -.54, P < .0001) with knee diameters, and weakly (r = -.35, P = .01) with laboratory indices (high threshold for analysis). CONCLUSION BOLD MRI has a substantial or excellent interframework reliability for assessment of arthritic rabbit knees; however, it correlates only moderately or poorly with clinical and laboratory measures. Nevertheless, this study supports further validation of BOLD MRI for assessment of soft tissue changes in a rabbit model of arthritis.
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Zhang Y, Peng Q, Kiel JW, Rosende CA, Duong TQ. Magnetic resonance imaging of vascular oxygenation changes during hyperoxia and carbogen challenges in the human retina. Invest Ophthalmol Vis Sci 2011; 52:286-91. [PMID: 20847121 PMCID: PMC3053278 DOI: 10.1167/iovs.10-6108] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 08/11/2010] [Accepted: 08/11/2010] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To demonstrate blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) of vascular oxygenation changes in normal, unanesthetized human retinas associated with oxygen and carbogen challenge. METHODS MRI was performed with a 3-T human scanner and a custom-made surface-coil detector on normal volunteers. BOLD MRI with inversion recovery was used to suppress the vitreous signal. During MRI measurements, volunteers underwent three episodes of air and 100% oxygen or carbogen (5% CO(2) and 95% O(2)) breathing. Eye movement was effectively managed with eye fixation, synchronized blinks, and postprocessing image coregistration. BOLD time-series images were analyzed using the cross-correlation method. Percent changes due to oxygen or carbogen inhalation versus air were tabulated for whole-retina and different regions of the retina. RESULTS Robust BOLD responses were detected. BOLD MRI percent change from a large region of interest at the posterior pole of the retina was 5.2 ± 1.5% (N = 9 trials from five subjects) for oxygen inhalation and 5.2 ± 1.3% (N = 11 trials from five subjects) for carbogen inhalation. Group-averaged BOLD percent changes were not significantly different between oxygen and carbogen challenges (P > 0.05). The foveal region had greater BOLD response compared with the optic nerve head region for both challenges. CONCLUSIONS BOLD retinal responses to oxygen and carbogen breathing in unanesthetized humans can be reliably imaged at high spatiotemporal resolution. BOLD MRI has the potential to provide a valuable tool to study retinal physiology and pathophysiology, such as how vascular oxygenation at the tissue level is regulated in the normal retina, and how retinal diseases may affect oxygen response.
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Affiliation(s)
- Yi Zhang
- From the Research Imaging Institute and
- the Departments of Radiology
| | - Qi Peng
- From the Research Imaging Institute and
- the Departments of Radiology
| | | | | | - Timothy Q. Duong
- From the Research Imaging Institute and
- the Departments of Radiology
- Ophthalmology, and
- Physiology, University of Texas Health Science Center, San Antonio, Texas; and
- South Texas Veterans Health Care System, San Antonio, Texas
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Small SA. Neurobiological correlates of imaging. NETWORK (BRISTOL, ENGLAND) 2011; 22:162-172. [PMID: 22149677 DOI: 10.3109/0954898x.2011.638695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Mark CI, Fisher JA, Pike GB. Improved fMRI calibration: precisely controlled hyperoxic versus hypercapnic stimuli. Neuroimage 2010; 54:1102-11. [PMID: 20828623 DOI: 10.1016/j.neuroimage.2010.08.070] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 07/11/2010] [Accepted: 08/31/2010] [Indexed: 10/19/2022] Open
Abstract
The calibration of functional magnetic resonance imaging (fMRI) for the estimation of neuronal activation-induced changes in cerebral metabolic rate of oxygen (CMRO(2)) has been achieved through hypercapnic-induced iso-metabolic increases in cerebral blood flow (CBF). Hypercapnia (HC) has been traditionally implemented through alterations in the fixed inspired fractional concentrations of carbon dioxide (F(I)CO(2)) without otherwise controlling end-tidal partial pressures of carbon dioxide (P(ET)CO(2)) or oxygen (P(ET)O(2)). There are several shortcomings to the use of this manual HC method that may be improved by using precise targeting of P(ET)CO(2) while maintaining iso-oxia. Similarly, precise control of blood gases can be used to induce isocapnic hyperoxia (HO) to reduce venous deoxyhaemoglobin (dHb) and thus increase BOLD signals, without appreciably altering CMRO(2) or CBF. The aim of our study was to use precise end-tidal targeting to compare the calibration of BOLD signals under an isocapnic hyperoxic protocol (HOP) (rises in P(ET)O(2) to 140, 240 and 340 mm Hg from baseline) to that of an iso-oxic hypercapnic protocol (HCP) (rises in P(ET)CO(2) of 3, 5, 7 and 9 mm Hg from baseline). Nine healthy volunteers were imaged at 3T while monitoring end-tidal gas concentrations and simultaneously measuring BOLD and CBF signals, via arterial spin labeling (ASL), during graded HCP and HOP, alternating with normocapnic states in a blocked experimental design. The variability of the calibration constant obtained under HOP (M(HOP)) was 0.3-0.5 that of the HCP one (M(HCP)). In addition, M-variances with precise gas targeting (M(HCP) and M(HOP)) were less than those reported in studies using traditional F(I)CO(2) and F(I)O(2) methods (M(HC) and M(HO), respectively). We conclude that precise controlled gas delivery markedly improves BOLD-calibration for fMRI studies of oxygen metabolism with both the HCP and the more precise HOP-alternative.
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Affiliation(s)
- Clarisse I Mark
- McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
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Mark CI, Slessarev M, Ito S, Han J, Fisher JA, Pike GB. Precise control of end-tidal carbon dioxide and oxygen improves BOLD and ASL cerebrovascular reactivity measures. Magn Reson Med 2010; 64:749-56. [DOI: 10.1002/mrm.22405] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Global cerebral oxidative metabolism during hypercapnia and hypocapnia in humans: implications for BOLD fMRI. J Cereb Blood Flow Metab 2010; 30:1094-9. [PMID: 20372169 PMCID: PMC2949195 DOI: 10.1038/jcbfm.2010.42] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effect of carbon dioxide (CO(2)) on cerebral metabolism is of tremendous interest to functional imaging. In particular, mild-to-moderate hypercapnia is routinely used in calibrated blood oxygen-level dependent (BOLD)-functional magnetic resonance imaging (fMRI)-based quantification of cerebral oxidative metabolism changes (DeltaCMRO(2)), and relies on the assumption of a stable CMRO(2) during CO(2) challenges. However, this assumption has been challenged by certain animal studies, necessitating its verification in humans and under conditions customary to fMRI. We report, for the first time, on global DeltaCMRO(2) measurements made noninvasively in humans during graded hypercapnia and hypocapnia. We used computerized end-tidal CO(2) modulation to minimize undesired concurrent changes in oxygen pressure, and our findings suggest that no significant change in global CMRO(2) is expected at the levels of end-tidal CO(2) changes customary to calibrated BOLD.
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Rioja E, Kerr CL, McDonell WN, Dobson H, Konyer NB, Poma R, Noseworthy MD. Effects of hypercapnia, hypocapnia, and hyperoxemia on blood oxygenation level-dependent signal intensity determined by use of susceptibility-weighted magnetic resonance imaging in isoflurane-anesthetized dogs. Am J Vet Res 2010; 71:24-32. [PMID: 20043777 DOI: 10.2460/ajvr.71.1.24] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess the effects of alterations in PaCO(2) and PaO(2) on blood oxygenation level-dependent (BOLD) signal intensity determined by use of susceptibility-weighted magnetic resonance imaging in brains of isoflurane-anesthetized dogs. ANIMALS 6 healthy dogs. PROCEDURES In each dog, anesthesia was induced with propofol (6 to 8 mg/kg, IV) and maintained with isoflurane (1.7%) and atracurium (0.2 mg/kg, IV, q 30 min). During 1 magnetic resonance imaging session in each dog, targeted values of PaCO(2) (20, 40, or 80 mm Hg) and PaO(2) (100 or 500 mm Hg) were combined to establish 6 experimental conditions, including a control condition (PaCO(2), 40 mm Hg; PaO(2), 100 mm Hg). Dogs were randomly assigned to different sequences of conditions. Each condition was established for a period of >or= 5 minutes before susceptibility-weighted imaging was performed. Signal intensity was measured in 6 regions of interest in the brain, and data were analyzed by use of an ANCOVA and post hoc Tukey-Kramer adjustments. RESULTS Compared with control condition findings, BOLD signal intensity did not differ significantly in any region of interest. However, signal intensities in the thalamus and diencephalic gray matter decreased significantly during both hypocapnic conditions, compared with all other conditions except for the control condition. CONCLUSIONS AND CLINICAL RELEVANCE In isoflurane-anesthetized dogs, certain regions of gray matter appeared to have greater cerebrovascular responses to changes in PaCO(2) and PaO(2) than did others. Both PaO(2) and PaCO(2) should be controlled during magnetic resonance imaging procedures that involve BOLD signaling and taken into account when interpreting findings.
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Affiliation(s)
- Eva Rioja
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
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Chopra S, Foltz WD, Milosevic MF, Toi A, Bristow RG, Ménard C, Haider MA. Comparing oxygen-sensitive MRI (BOLD R2*) with oxygen electrode measurements: a pilot study in men with prostate cancer. Int J Radiat Biol 2009; 85:805-13. [PMID: 19728195 DOI: 10.1080/09553000903043059] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE To explore the relationship between oxygen-sensitive Magnetic Resonance Imaging (MRI) and oxygen measurements in prostate cancer. METHODS Nine men underwent MRI examinations followed by needle oxygen measurements of tumor bearing region within prostate gland and five men further consented to biopsy. Median pO2 and hypoxic fraction < 5 mm Hg (HP5) were derived. Biopsies were immunostained for Carbonic Anhydrase IX (CA IX), Hypoxia Inducible Factor-1 (HIF 1) and Glucose Transporter-1 (GLUT 1). Corresponding Regions-of-Interest (ROI) were delineated on T2-weighted (T2w) MRI by two observers. Median R2* was calculated for each ROI. Spearman correlation was calculated between R2* and HP5/pO2. RESULTS MRI quality evaluation resulted in exclusion of 4/18 ROI due to motion (n = 2) and rectal air susceptibility artifact (n = 2). Quality of remaining data was validated by concordance of R2* with T2w, indices and with secondary observer R2* (r = 0.94, p = 0.005). Correlation was observed between R2* and HP5 (r = 0.76, p = 0.02) and a trend was noted between R2* and pO2 (r = -0.66, p = 0.07). GLUT 1 and HIF 1 were expressed in all patients, and CA IX was expressed in one patient with high HP5 (77%) and low pO2 (1.4 mm Hg). CONCLUSIONS MRI using R2* quantification is a promising tool for non-invasive imaging of prostate cancer hypoxia.
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Affiliation(s)
- Supriya Chopra
- Department of Radiation Oncology, University Health Network, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada
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Boss A, Martirosian P, Jehs MC, Dietz K, Alber M, Rossi C, Claussen CD, Schick F. Influence of oxygen and carbogen breathing on renal oxygenation measured by T2*-weighted imaging at 3.0 T. NMR IN BIOMEDICINE 2009; 22:638-645. [PMID: 19306339 DOI: 10.1002/nbm.1378] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The aim of the study was to assess the influence of carbogen (95% O(2), 5% CO(2)) or pure oxygen breathing on renal oxygenation measured by blood oxygenation level dependent (BOLD) magnetic resonance imaging at 3.0 T. Seven healthy young volunteers (median age 25, range 23-35 years) participated in the study. A T2*-weighted fat-saturated spoiled gradient-echo sequence was implemented on a 3.0 T whole-body imager (TE/TR = 27.9 ms/49 ms, excitation angle 20 degrees ) with an acquisition time of approximately 5.3 s. A total of 100 images were acquired during 22 min. A block design was applied for gas administration: 4 min room air, 4 min carbogen/oxygen, 4 min room air, 4 min carbogen/oxygen and 6 min room air. A compartment model was fitted to the data sets accounting for time-dependent increase/decrease of renal oxygenation as well as baseline changes of the scanner. T2*-weighted images showed good image quality without notable artefacts or distortions. Mean relative signal increase due to carbogen breathing was 2.73% (95% confidence interval: 1.34-5.54) in the right kidney and 3.76% (1.53-9.20) in the left kidney, while oxygen breathing led to a signal enhancement of 3.20% (2.57-3.98) in the right kidney and 3.16% (1.83-5.45) in the left kidney. No statistical difference was found between carbogen and oxygen breathing or between the oxygenation of the right and the left kidney. A significant difference was found in the characteristic time constant for the signal increase with a faster saturation taking place for oxygen breathing. Renal tissue oxygenation is clearly influenced by carbogen or oxygen breathing. The changes can be assessed by T2*-weighted MRI at high field strengths. The effects are in the expected range for the BOLD effect of 3-4% at 3.0 T. The proposed technique might be interesting for the assessment of renal tissue oxygenation and its regulation in patients with kidney diseases.
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Affiliation(s)
- Andreas Boss
- Section of Experimental Radiology, Eberhard-Karls University, Hoppe-Seyler-Strasse 3, Tübingen, Germany.
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O'Connor JPB, Naish JH, Jackson A, Waterton JC, Watson Y, Cheung S, Buckley DL, McGrath DM, Buonaccorsi GA, Mills SJ, Roberts C, Jayson GC, Parker GJM. Comparison of normal tissue R1 and R*2 modulation by oxygen and carbogen. Magn Reson Med 2009; 61:75-83. [PMID: 19097212 DOI: 10.1002/mrm.21815] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Accepted: 08/13/2008] [Indexed: 12/22/2022]
Abstract
Magnetic resonance imaging has shown promise for evaluating tissue oxygenation. In this study differences in the tissue longitudinal relaxation rate (R(1)) and effective transverse relaxation rate (R(*)(2)), induced by inhalation of pure oxygen and carbogen, were evaluated in 10 healthy subjects. Significant reductions in R(1) were demonstrated following both oxygen and carbogen inhalation in the spleen (both P < 0.001), liver (P = 0.002 air vs. oxygen; P = 0.001 air vs. carbogen), skeletal muscle (both P < 0.001), and renal cortex (P = 0.005 air vs. oxygen; P = 0.008 air vs. carbogen). No significant change in R(*)(2) occurred following pure oxygen in any organ. However, a significant increase in R(*)(2) was observed in the spleen (P < 0.001), liver (P = 0.001), skeletal muscle (P = 0.026), and renal cortex (P = 0.001) following carbogen inhalation, an opposite effect to that observed in many studies of tumor pathophysiology. Changes in R(1) and R(*)(2) were independent of the gas administration order in the spleen and skeletal muscle. These findings suggest that the R(1) and R(*)(2) responses to hyperoxic gases are independent biomarkers of oxygen physiology.
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Affiliation(s)
- James P B O'Connor
- Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK. james.o'
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Investigation of the influence of carbon dioxide concentrations on cerebral physiology by susceptibility-weighted magnetic resonance imaging (SWI). Neuroimage 2008; 43:36-43. [PMID: 18678260 DOI: 10.1016/j.neuroimage.2008.07.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 06/26/2008] [Accepted: 07/01/2008] [Indexed: 01/31/2023] Open
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Zaharchuk G, Martin AJ, Dillon WP. Noninvasive imaging of quantitative cerebral blood flow changes during 100% oxygen inhalation using arterial spin-labeling MR imaging. AJNR Am J Neuroradiol 2008; 29:663-7. [PMID: 18397966 DOI: 10.3174/ajnr.a0896] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Tracer studies have demonstrated that 100% oxygen inhalation causes a small cerebral blood flow (CBF) decrease. This study was performed to determine whether arterial spin-labeling (ASL), a noninvasive MR imaging technique, could image these changes with clinically reasonable imaging durations. MATERIALS AND METHODS Continuous ASL imaging was performed in 7 healthy subjects before, during, and after 100% oxygen inhalation. ASL difference signal intensity (DeltaM, control - label), CBF, and CBF percentage change were measured. A test-retest paradigm was used to calculate the variability of the initial and final room air CBF measurements. RESULTS During oxygen inhalation, DeltaM decreased significantly in all regions (eg, global DeltaM decreased by 23 +/- 11%, P < .01, all values mean +/- SD). Accounting for the reduced T1 of hyperoxygenated blood, we found a smaller CBF decrease, which did not reach significance in any of the regions. Global CBF dropped from 50 +/- 10 mL per 100 g/minute to 47 +/- 10 mL per 100 g/minute following 100% oxygen inhalation, a decrease of 5 +/- 14% (P > .17). The root-mean-square variability of the initial and final room air CBF measurements was 7-8 mL per 100 g/minute. CONCLUSIONS The DeltaM signal intensity decreased significantly with oxygen inhalation; however, after accounting for changes in blood T1 with oxygen, CBF decreases were small. Such measurements support the use of hyperoxia as an MR imaging contrast agent and may be helpful to interpret hyperoxia-based stroke trials.
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Affiliation(s)
- G Zaharchuk
- Department of Radiology, Stanford University, Stanford, CA 94305-5487, USA.
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Bulte D, Chiarelli P, Wise R, Jezzard P. Measurement of cerebral blood volume in humans using hyperoxic MRI contrast. J Magn Reson Imaging 2008; 26:894-9. [PMID: 17896390 DOI: 10.1002/jmri.21096] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop a new method of measuring quantitative regional cerebral blood volume (CBV) using epochs of hyperoxia as an intravenous contrast agent with T2*-weighted MRI. MATERIALS AND METHODS Images were acquired from six subjects (four male, two female, mean age 29 +/- 3.7 years) using a sequence combining pulsed arterial spin labeling interleaved with a gradient echo echo-planar imaging (EPI) blood oxygenation level-dependent (BOLD) sequence at 3T. The hyperoxia paradigm lasted 28 minutes consisting of 4 minutes of normoxia, two 6-minute blocks of hyperoxia separated by 6 minutes of normoxia. During the hyperoxic blocks the subjects were delivered a fractional oxygen concentration of 0.5. RESULTS The mean CBV was calculated to be 3.77 +/- 1.05 mL/100 g globally, 3.93 +/- 0.90 mL/100 g in gray matter (GM), and 2.52 +/- 0.78 mL/100 g in white matter (WM). The mean GM/WM ratio was thus found to be 1.56. These values are comparable to those obtained in other studies. CONCLUSION The hyperoxia technique for measuring CBV may be particularly useful for patient groups where an injected bolus of contrast agent is contraindicated. As more functional studies are employing epochs of inspired gases for calibration purposes, this method is easily incorporated into existing paradigms to produce a noninvasive, repeatable, easily tolerated, and quantitative measurement of regional CBV.
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Affiliation(s)
- Daniel Bulte
- FMRIB Centre, Department of Clinical Neurology, University of Oxford, Oxford, UK.
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Barash H, Gross E, Matot I, Edrei Y, Tsarfaty G, Spira G, Vlodavsky I, Galun E, Abramovitch R. Functional MR imaging during hypercapnia and hyperoxia: noninvasive tool for monitoring changes in liver perfusion and hemodynamics in a rat model. Radiology 2007; 243:727-35. [PMID: 17463135 DOI: 10.1148/radiol.2433060433] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PURPOSE To prospectively assess functional magnetic resonance (MR) imaging during hypercapnia and hyperoxia for monitoring changes in liver perfusion and hemodynamics in rats. MATERIALS AND METHODS All experiments were performed with approval of an animal care and use committee. Functional T2*-weighted gradient-echo MR images of the rat liver were acquired during hyperoxia and graded hypercapnia (n=24). Additional images were acquired during portal vein ligation (n=4), induced hypovolemia (n=5), and 70% hepatectomy (n=5). Hypercapnic effects were confirmed with Doppler ultrasonography and with gadopentetate dimeglumine. Differences between groups were analyzed by using Wilcoxon rank sum test, except for the graded hypercapnia, for which one-way analysis of variance was used. RESULTS Liver signal intensity (SI) increased due to hyperoxia; the percentage change in SI was seven times greater than that in muscle tissue; this reflects higher vascularity of the liver. Liver SI decreased due to hypercapnia; the percentage change in SI was negative in the liver but positive in the muscle (P<.001). Induced hypovolemia resulted in considerable decreases in functional MR imaging response; this reflects lower liver perfusion. Clinical applicability of the functional MR imaging method was proved by monitoring changes in liver perfusion that resulted from liver resection. CONCLUSION In the liver, the magnitude of the percentage change in SI induced by hypercapnia and hyperoxia reflects changes in total blood volume; whereas percentage change in SI values induced by hypercapnia from a negative to a positive value reflects relative changes in portal-to-arterial blood flow ratio.
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Affiliation(s)
- Hila Barash
- Goldyne Savad Institute for Gene Therapy, MRI/MRS Lab HBRC, Hadassah Hebrew University Medical Center, POB 12000, Jerusalem 91120, Israel
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Prisman E, Slessarev M, Han J, Poublanc J, Mardimae A, Crawley A, Fisher J, Mikulis D. Comparison of the effects of independently-controlled end-tidal PCO2 and PO2 on blood oxygen level–dependent (BOLD) MRI. J Magn Reson Imaging 2007; 27:185-91. [DOI: 10.1002/jmri.21102] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Abstract
Graded levels of supplemental inspired oxygen were investigated for their viability as a noninvasive method of obtaining intravascular magnetic resonance image contrast. Administered hyperoxia has been shown to be effective as a blood oxygenation level-dependent contrast agent for magnetic resonance imaging (MRI); however, it is known that high levels of inspired fraction of oxygen result in regionally decreased perfusion in the brain potentially confounding the possibility of using hyperoxia as a means of measuring blood flow and volume. Although the effects of hypoxia on blood flow have been extensively studied, the hyperoxic regime between normoxia and 100% inspired oxygen has been only intermittently studied. Subjects were studied at four levels of hyperoxia induced during a single session while perfusion was measured using arterial spin labelling MRI. Reductions in regional perfusion of grey matter were found to occur even at moderate levels of hyperoxia; however, perfusion changes at all oxygen levels were relatively mild (less than 10%) supporting the viability of hyperoxia-induced contrast.
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Affiliation(s)
- Daniel P Bulte
- FMRIB Centre, Department of Clinical Neurology, University of Oxford, Oxford, UK.
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Rauscher A, Sedlacik J, Barth M, Haacke EM, Reichenbach JR. Nonnvasive assessment of vascular architecture and function during modulated blood oxygenation using susceptibility weighted magnetic resonance imaging. Magn Reson Med 2005; 54:87-95. [PMID: 15968657 DOI: 10.1002/mrm.20520] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Susceptibility weighted imaging (SWI) is a BOLD-sensitive method for visualizing anatomical features such as small cerebral veins in high detail. The purpose of this study was to evaluate high-resolution SWI in combination with a modulation of blood oxygenation by breathing of air, carbogen, and oxygen and to directly visualize the effects of changing blood oxygenation on the magnetic field inside and around venous blood vessels. Signal changes associated with the response to carbogen and oxygen breathing were evaluated in different anatomic regions in healthy volunteers and in two patients with brain tumors. In the magnitude images inhalation of carbogen led to significant signal intensity changes ranging from +4.4 +/- 1.9% to +9.5 +/- 1.4% in gray matter and no significant changes in thalamus, putamen, and white matter. During oxygen breathing mean signal changes were smaller than during carbogen breathing. The method is capable of producing high-resolution functional maps of BOLD response to carbogen and oxygen breathing as well as high-resolution images of venous vasculature. Its sensitivity to changes in blood oxygenation was demonstrated by in vivo visualization of the BOLD effect via phase imaging.
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Affiliation(s)
- Alexander Rauscher
- Institute for Diagnostic and Interventional Radiology, Friedrich Schiller University, Jena, Germany
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Abstract
Prior reviews on the topic of imaging and Alzheimer's disease have focused predominately on the technical features of imaging modalities or have summarized the results of epidemiologic studies. As brain scientists and brain practitioners, our main focus should be on the neurobiologic correlates of imaging, so we can intertwine this knowledge with our understanding of disease pathophysiology. A focus on these two features--the neurobiologic correlates of imaging and the pathophysiology of Alzheimer's disease--has provided the organizing principle of this review.
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Affiliation(s)
- Scott A Small
- Department of Neurology, Columbia University College of Physicians and Surgeons, PH 19th Floor, 630 West 168 Street, New York, NY 10032, USA.
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