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Thomas DG, Galvosas P, Tzeng YC, Harrison FG, Berry MJ, Teal PD, Wright GA, Obruchkov S. Oxygen saturation-dependent effects on blood transverse relaxation at low fields. MAGMA (NEW YORK, N.Y.) 2022; 35:805-815. [PMID: 35107697 PMCID: PMC9463268 DOI: 10.1007/s10334-021-00993-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/28/2021] [Accepted: 12/15/2021] [Indexed: 11/28/2022]
Abstract
Objective Blood oxygenation can be measured using magnetic resonance using the paramagnetic effect of deoxy-haemoglobin, which decreases the \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 relaxation time of blood. This \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 contrast has been well characterised at the \documentclass[12pt]{minimal}
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\begin{document}$$\textit{B}_{{0}}$$\end{document}B0 fields used in MRI (1.5 T and above). However, few studies have characterised this effect at lower magnetic fields. Here, the feasibility of blood oximetry at low field based on \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 changes that are within a physiological relevant range is explored. This study could be used for specifying requirements for construction of a monitoring device based on low field permanent magnet systems. Methods A continuous flow circuit was used to control parameters such as oxygen saturation and temperature in a sample of blood. It flowed through a variable field magnet, where CPMG experiments were performed to measure its \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2. In addition, the oxygen saturation was monitored by an optical sensor for comparison with the \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 changes. Results These results show that at low \documentclass[12pt]{minimal}
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\begin{document}$$\textit{B}_{{0}}$$\end{document}B0 fields, the change in blood \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 due to oxygenation is small, but still detectable. The data measured at low fields are also in agreement with theoretical models for the oxy-deoxy \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 effect. Conclusion \documentclass[12pt]{minimal}
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\begin{document}$$\textit{T}_{2}$$\end{document}T2 changes in blood due to oxygenation were observed at fields as low as 0.1 T. These results suggest that low field NMR relaxometry devices around 0.3 T could be designed to detect changes in blood oxygenation.
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Affiliation(s)
- Dion G Thomas
- School of Chemical and Physical Sciences and MacDiarmid Institute for Advanced Materials, Victoria University of Wellington, Wellington, New Zealand
| | - Petrik Galvosas
- School of Chemical and Physical Sciences and MacDiarmid Institute for Advanced Materials, Victoria University of Wellington, Wellington, New Zealand
| | - Yu-Chieh Tzeng
- Centre for Translational Research, University of Otago, Wellington, New Zealand
| | - Freya G Harrison
- Centre for Translational Research, University of Otago, Wellington, New Zealand
| | - Mary J Berry
- Centre for Translational Research and Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand
| | - Paul D Teal
- School of Engineering and Computer Science, Victoria University of Wellington, Wellington, New Zealand
| | - Graham A Wright
- Sunnybrook Research Institute and University of Toronto, Toronto, ON, Canada
| | - Sergei Obruchkov
- Robinson Research Institute, Victoria University of Wellington, Wellington, New Zealand.
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2
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Ruschke S, Syväri J, Dieckmeyer M, Junker D, Makowski MR, Baum T, Karampinos DC. Physiological variation of the vertebral bone marrow water T2 relaxation time. NMR IN BIOMEDICINE 2021; 34:e4439. [PMID: 33205520 DOI: 10.1002/nbm.4439] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/09/2020] [Accepted: 10/14/2020] [Indexed: 06/11/2023]
Abstract
The aim of this study was to investigate physiological variations of the water T2 relaxation time in vertebral bone marrow with respect to age, body mass index (BMI), sex and proton density fat fraction (PDFF) based on single-voxel magnetic resonance spectroscopy (MRS) at 3 T. Multi-TE single-voxel STEAM MRS data of a single lumbar vertebra (L4 or L5) from 260 subjects (160/100 female/male, age: 0.7/37.1/77.7 years, BMI: 13.6/26.2/44.5 kg/m2 [min./median/max.]) with no history of vertebral bone marrow pathologies were retrospectively included. All data were processed using a joint series T2-constrained time domain-based water-fat model. Water T2 and PDFF data were analyzed using (a) Pearson's correlation r and (b) multiple linear regression without interactions of the independent variables. Min./median/max. water T2 and PDFF were 11.2/21.1/42.5 ms and 4.0%/36.8%/82.0%, respectively. Pearson's correlation coefficients were significant (P < .05) for water T2 versus age (r = -0.429/-0.210 female/male) and for water T2 versus PDFF (r = -0.580/-0.546 female/male) for females and males, respectively. Females showed significant higher water T2 values compared with males (P < .001). Multiple linear regression for water T2 without interactions revealed a R2 = 0.407 with PDFF (P < .001) and sex (P < .001) as significant predictors. The current study suggests that under physiological conditions vertebral bone marrow water T2 is negatively correlated with age and PDFF and shows significant differences between females and males. The observed systematic trends are of relevance for the evaluation of T2 values and T2-weighted bone marrow parameters. Further research on the exact mechanisms and drivers of the observed water T2 behavior is required.
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Affiliation(s)
- Stefan Ruschke
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jan Syväri
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Michael Dieckmeyer
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Daniela Junker
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Marcus R Makowski
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Thomas Baum
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Dimitrios C Karampinos
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
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The application of in utero magnetic resonance imaging in the study of the metabolic and cardiovascular consequences of the developmental origins of health and disease. J Dev Orig Health Dis 2020; 12:193-202. [PMID: 33308364 PMCID: PMC8162788 DOI: 10.1017/s2040174420001154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Observing fetal development in utero is vital to further the understanding of later-life diseases. Magnetic resonance imaging (MRI) offers a tool for obtaining a wealth of information about fetal growth, development, and programming not previously available using other methods. This review provides an overview of MRI techniques used to investigate the metabolic and cardiovascular consequences of the developmental origins of health and disease (DOHaD) hypothesis. These methods add to the understanding of the developing fetus by examining fetal growth and organ development, adipose tissue and body composition, fetal oximetry, placental microstructure, diffusion, perfusion, flow, and metabolism. MRI assessment of fetal growth, organ development, metabolism, and the amount of fetal adipose tissue could give early indicators of abnormal fetal development. Noninvasive fetal oximetry can accurately measure placental and fetal oxygenation, which improves current knowledge on placental function. Additionally, measuring deficiencies in the placenta’s transport of nutrients and oxygen is critical for optimizing treatment. Overall, the detailed structural and functional information provided by MRI is valuable in guiding future investigations of DOHaD.
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Stolz M, Schlawne C, Hoffmann J, Hartmann V, Marini I, Fritsche A, Peter A, Bakchoul T, Schick F. Feasibility of precise and reliable glucose quantification in human whole blood samples by 1 tesla benchtop NMR. NMR IN BIOMEDICINE 2020; 33:e4358. [PMID: 32618045 DOI: 10.1002/nbm.4358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 05/15/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
The standard procedure for blood glucose measurements is enzymatic testing. This method is cheap, but requires small samples of open blood with direct contact to the test medium. In principle, NMR provides non-contact analysis of body fluids, but high-field spectrometers are expensive and cannot be easily utilized under clinical conditions. Low-field NMR systems with permanent magnets are becoming increasingly smaller and more affordable. The studies presented here aim at exploring the capabilities of low-field NMR for measuring glucose concentrations in whole blood. For this purpose, a modern 1 T benchtop NMR spectrometer was used. Challenges arise from broad spectral lines, the glucose peak locations close to the water signal, low SNR and the interference with signals from other blood components. Whole blood as a sample comprises even more boundary conditions: crucial for reliable results are avoiding the separation of plasma and cells by gravitation and reliable reference values. First, the accuracy of glucose levels measured by NMR was tested using aqueous glucose solutions and commercially available bovine plasma. Then, 117 blood samples from oral glucose tolerance testing were measured with minimal preparation by simple pulse-acquire NMR experiments. The analysis itself is the key to achieve high precision, so several approaches were investigated: peak integration, orthogonal projection to latent structure analysis and support vector machine regression. Correlations between results from the NMR spectra and the routine laboratory automated analyzer revealed an RMSE of 7.90 mg/dL for the best model. 91.5% of the model output lies within the limits of the German Medical Association guidelines, which require the glucose measurement to be within 11% of the reference method. It is concluded that spectral quantification of glucose in whole blood samples by high-quality NMR spectrometers operating at 1 T is feasible with sufficient accuracy.
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Affiliation(s)
- Michael Stolz
- Department of Transfusion Medicine, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | | | | | - Vanessa Hartmann
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, University of Tuebingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD e.V.), Tuebingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Irene Marini
- Department of Transfusion Medicine, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Andreas Fritsche
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, University of Tuebingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD e.V.), Tuebingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Andreas Peter
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, University of Tuebingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD e.V.), Tuebingen, Germany
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital Tuebingen, Tuebingen, Germany
| | - Tamam Bakchoul
- Department of Transfusion Medicine, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Fritz Schick
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, University of Tuebingen, Tuebingen, Germany
- Department of Radiology, Section on Experimental Radiology, Eberhard Karls University Tuebingen, Tuebingen, Germany
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Li W, van Zijl PC. Quantitative theory for the transverse relaxation time of blood water. NMR IN BIOMEDICINE 2020; 33:e4207. [PMID: 32022362 PMCID: PMC7322972 DOI: 10.1002/nbm.4207] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 09/19/2019] [Accepted: 10/01/2019] [Indexed: 05/08/2023]
Abstract
An integrative model is proposed to describe the dependence of the transverse relaxation rate of blood water protons (R2blood = 1/T2blood ) on hematocrit fraction and oxygenation fraction (Y). This unified model takes into account (a) the diamagnetic effects of albumin, hemoglobin and the cell membrane; (b) the paramagnetic effect of hemoglobin; (c) the effect of compartmental exchange between plasma and erythrocytes under both fast and slow exchange conditions that vary depending on field strength and compartmental relaxation rates and (d) the effect of diffusion through field gradients near the erythrocyte membrane. To validate the model, whole-blood and lysed-blood R2 data acquired previously using Carr-Purcell-Meiboom-Gill measurements as a function of inter-echo spacing τcp at magnetic fields of 3.0, 7.0, 9.4 and 11.7 T were fitted to determine the lifetimes (field-independent physiological constants) for water diffusion and exchange, as well as several physical constants, some of which are field-independent (magnetic susceptibilities) and some are field-dependent (relaxation rates for water protons in solutions of albumin and oxygenated and deoxygenated hemoglobin, ie, blood plasma and erythrocytes, respectively). This combined exchange-diffusion model allowed excellent fitting of the curve of the τcp -dependent relaxation rate dispersion at all four fields using a single average erythrocyte water lifetime, τery = 9.1 ± 1.4 ms, and an averaged diffusional correlation time, τD = 3.15 ± 0.43 ms. Using this model and the determined physiological time constants and relaxation parameters, blood T2 values published by multiple groups based on measurements at magnetic field strengths of 1.5 T and higher could be predicted correctly within error. Establishment of this theory is a fundamental step for quantitative modeling of the BOLD effect underlying functional MRI.
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Affiliation(s)
- Wenbo Li
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Peter C.M. van Zijl
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
- Correspondence: Peter C.M. van Zijl, PhD, F. M. Kirby Research Center for Functional Brain Imaging, The Kennedy Krieger Institute, 707 N. Broadway, Room G-25, Baltimore, MD, 21205, United States of America, , Tel: 443-923-9500, Fax: 443-923-9505
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6
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Lee DY, Kang S, Lee Y, Kim JY, Yoo D, Jung W, Lee S, Jeong YY, Lee K, Jon S. PEGylated Bilirubin-coated Iron Oxide Nanoparticles as a Biosensor for Magnetic Relaxation Switching-based ROS Detection in Whole Blood. Theranostics 2020; 10:1997-2007. [PMID: 32104497 PMCID: PMC7019166 DOI: 10.7150/thno.39662] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/16/2019] [Indexed: 12/13/2022] Open
Abstract
Rationale: Magnetic relaxation switching (MRSw) induced by target-triggered aggregation or dissociation of superparamagnetic iron oxide nanoparticles (SPIONs) have been utilized for detection of diverse biomarkers. However, an MRSw-based biosensor for reactive oxygen species (ROS) has never been documented. Methods: To this end, we constructed a biosensor for ROS detection based on PEGylated bilirubin (PEG-BR)-coated SPIONs (PEG-BR@SPIONs) that were prepared by simple sonication via ligand exchange. In addition, near infra-red (NIR) fluorescent dye was loaded onto PEG-BR@SPIONs as a secondary option for fluorescence-based ROS detection. Results: PEG-BR@SPIONs showed high colloidal stability under physiological conditions, but upon exposure to the model ROS, NaOCl, in vitro, they aggregated, causing a decrease in signal intensity in T2-weighted MR images. Furthermore, ROS-responsive PEG-BR@SPIONs were taken up by lipopolysaccharide (LPS)-activated macrophages to a much greater extent than ROS-unresponsive control nanoparticles (PEG-DSPE@SPIONs). In a sepsis-mimetic clinical setting, PEG-BR@SPIONs were able to directly detect the concentrations of ROS in whole blood samples through a clear change in T2 MR signals and a 'turn-on' signal of fluorescence. Conclusions: These findings suggest that PEG-BR@SPIONs have the potential as a new type of dual mode (MRSw-based and fluorescence-based) biosensors for ROS detection and could be used to diagnose many diseases associated with ROS overproduction.
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Related Research and Recent Progress of Ischemic Penumbra. World Neurosurg 2018; 116:5-13. [DOI: 10.1016/j.wneu.2018.04.193] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 11/20/2022]
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Rodríguez-Soto AE, Abdulmalik O, Langham MC, Schwartz N, Lee H, Wehrli FW. T 2 -prepared balanced steady-state free precession (bSSFP) for quantifying whole-blood oxygen saturation at 1.5T. Magn Reson Med 2018; 79:1893-1900. [PMID: 28718522 PMCID: PMC5771982 DOI: 10.1002/mrm.26835] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/06/2017] [Accepted: 06/21/2017] [Indexed: 11/11/2022]
Abstract
PURPOSE To establish a calibration equation to convert human blood T2 to the full range of oxygen saturation levels (HbO2 ) and physiologic hematocrit (Hct) values using a T2 -prepared balanced steady-state free precession sequence (T2 -SSFP) at 1.5T. METHODS Blood drawn from 10 healthy donors (29.1 ± 3.9 years old) was prepared into samples of varying HbO2 and Hct (n = 79), and imaged using T2 -SSFP sequence at 37°C and interrefocusing interval τ180 = 12 ms. The relationship between blood T2 , HbO2 , and Hct was established based on the model R2=R2,plasma+Hct (R2,RBC-R2,plasma)+k·Hct·(1-Hct)·(1-HbO2)2. Measured R2 and HbO2 levels were fit by the model yielding values of R2,plasma, R2,RBC, and k. T2 -SSFP and the established calibration equation were applied to extract HbO2 at the superior sagittal sinus (SSS) in vivo and were compared with susceptometry-based oximetry. RESULTS Constants derived from the fit were: k = 74.2 [s-1 ], R2,plasma = 1.5 [s-1 ], R2,RBC = 11.6 [s-1 ], the R2 of the fit was 0.95. Average HbO2 at the SSS in seven healthy volunteers was 65% ± 7% and 66% ± 7% via T2 - and susceptometry-based oximetry, respectively. Bland-Altman analysis indicated agreement between the two oximetric methods with no significant bias. CONCLUSION The calibration constants presented here should ensure improved accuracy for whole-blood oximetry based on T2 -SSFP at 1.5T. Magn Reson Med 79:1893-1900, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Ana E. Rodríguez-Soto
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | - Osheiza Abdulmalik
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Michael C. Langham
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | - Nadav Schwartz
- Maternal and Child Health Research Program, Department of OBGYN, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Hyunyeol Lee
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | - Felix W. Wehrli
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA
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Rodríguez-Soto AE, Langham MC, Abdulmalik O, Englund EK, Schwartz N, Wehrli FW. MRI quantification of human fetal O 2 delivery rate in the second and third trimesters of pregnancy. Magn Reson Med 2018; 80:1148-1157. [PMID: 29359353 DOI: 10.1002/mrm.27094] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 12/21/2017] [Accepted: 12/28/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Ana E Rodríguez-Soto
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael C Langham
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Osheiza Abdulmalik
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Erin K Englund
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nadav Schwartz
- Maternal and Child Health Research Program, Department of OBGYN, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Felix W Wehrli
- Laboratory for Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Varghese J, Potter LC, LaFountain R, Pan X, Raman SV, Ahmad R, Simonetti OP. CMR-based blood oximetry via multi-parametric estimation using multiple T2 measurements. J Cardiovasc Magn Reson 2017; 19:88. [PMID: 29121971 PMCID: PMC5680788 DOI: 10.1186/s12968-017-0403-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 10/18/2017] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Measurement of blood oxygen saturation (O2 saturation) is of great importance for evaluation of patients with many cardiovascular diseases, but currently there are no established non-invasive methods to measure blood O2 saturation in the heart. While T2-based CMR oximetry methods have been previously described, these approaches rely on technique-specific calibration factors that may not generalize across patient populations and are impractical to obtain in individual patients. We present a solution that utilizes multiple T2 measurements made using different inter-echo pulse spacings. These data are jointly processed to estimate all unknown parameters, including O2 saturation, in the Luz-Meiboom (L-M) model. We evaluated the accuracy of the proposed method against invasive catheterization in a porcine hypoxemia model. METHODS Sufficient data diversity to estimate the various unknown parameters of the L-M model, including O2 saturation, was achieved by acquiring four T2 maps, each at a different τ 180 (12, 15, 20, and 25 ms). Venous and arterial blood T2 values from these maps, together with hematocrit and arterial O2 saturation, were jointly processed to derive estimates for venous O2 saturation and other nuisance parameters in the L-M model. The technique was validated by a progressive graded hypoxemia experiment in seven pigs. CMR estimates of O2 saturation in the right ventricle were compared against a reference O2 saturation obtained by invasive catheterization from the right atrium in each pig, at each hypoxemia stage. O2 saturation derived from the proposed technique was also compared against the previously described method of applying a global calibration factor (K) to the simplified L-M model. RESULTS Venous O2 saturation results obtained using the proposed CMR oximetry method exhibited better agreement (y = 0.84× + 12.29, R2 = 0.89) with invasive blood gas analysis when compared to O2 saturation estimated by a global calibration method (y = 0.69× + 27.52, R2 = 0.73). CONCLUSIONS We have demonstrated a novel, non-invasive method to estimate O2 saturation using quantitative T2 mapping. This technique may provide a valuable addition to the diagnostic utility of CMR in patients with congenital heart disease, heart failure, and pulmonary hypertension.
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Affiliation(s)
- Juliet Varghese
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH USA
| | - Lee C. Potter
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH USA
| | - Richard LaFountain
- Department of Health and Exercise Science, The Ohio State University, Columbus, OH USA
| | - Xueliang Pan
- Center for Biostatistics, The Ohio State University, Columbus, OH USA
| | - Subha V. Raman
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH USA
- Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH USA
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH USA
| | - Rizwan Ahmad
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH USA
| | - Orlando P. Simonetti
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH USA
- Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH USA
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH USA
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Kang D, Sung YW, Shioiri S. Estimation of physiological sources of nonlinearity in blood oxygenation level-dependent contrast signals. Magn Reson Imaging 2017; 46:121-129. [PMID: 29122668 DOI: 10.1016/j.mri.2017.10.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 10/13/2017] [Accepted: 10/31/2017] [Indexed: 11/25/2022]
Abstract
Blood oxygenation level-dependent (BOLD) contrast appears through a variation in the transverse relaxation rate of magnetic resonance signals induced by neurovascular coupling and is known to have nonlinear characteristics along echo time (TE) due to the intra-vasculature. However, the physiological causes of this nonlinearity are unclear. We attempted to estimate the physiological information related to the nonlinearity of BOLD signals by using a two-compartment model. For this purpose, we used a multi-echo gradient-echo echo-planar imaging sequence and developed a computational method to estimate the physiological information from the TE-dependent BOLD signals. The results showed that the average chemical exchange time in the intra-vasculature varied during stimulation, which might be the essential source of the nonlinearity.
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Affiliation(s)
- Daehun Kang
- Kansei Fukushi Research Institute, Tohoku Fukushi University, Sendai, Japan; Graduate School of Information Sciences and Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
| | - Yul-Wan Sung
- Kansei Fukushi Research Institute, Tohoku Fukushi University, Sendai, Japan.
| | - Satoshi Shioiri
- Graduate School of Information Sciences and Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
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12
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Portnoy S, Milligan N, Seed M, Sled JG, Macgowan CK. Human umbilical cord blood relaxation times and susceptibility at 3 T. Magn Reson Med 2017; 79:3194-3206. [DOI: 10.1002/mrm.26978] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 09/01/2017] [Accepted: 09/27/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Sharon Portnoy
- Department of Medical Biophysics; University of Toronto; Toronto Ontario Canada
- Mouse Imaging Centre; Hospital for Sick Children; Toronto Ontario Canada
| | - Natasha Milligan
- Department of Obstetrics & Gynecology; Mount Sinai Hospital; Toronto Ontario Canada
| | - Mike Seed
- Division of Cardiology; Hospital for Sick Children; Toronto Ontario Canada
- Department of Pediatrics and Diagnostic Imaging; University of Toronto; Toronto Ontario Canada
| | - John G. Sled
- Department of Medical Biophysics; University of Toronto; Toronto Ontario Canada
- Mouse Imaging Centre; Hospital for Sick Children; Toronto Ontario Canada
- Department of Obstetrics and Gynecology; University of Toronto; Toronto Ontario Canada
| | - Christopher K. Macgowan
- Department of Medical Biophysics; University of Toronto; Toronto Ontario Canada
- Division of Translational Medicine; Hospital for Sick Children; Toronto Ontario Canada
- Labatt Family Heart Centre; Hospital for Sick Children; Toronto Ontario Canada
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13
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Xu F, Li W, Liu P, Hua J, Strouse JJ, Pekar JJ, Lu H, van Zijl PCM, Qin Q. Accounting for the role of hematocrit in between-subject variations of MRI-derived baseline cerebral hemodynamic parameters and functional BOLD responses. Hum Brain Mapp 2017; 39:344-353. [PMID: 29024300 DOI: 10.1002/hbm.23846] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/22/2017] [Accepted: 10/04/2017] [Indexed: 12/19/2022] Open
Abstract
Baseline hematocrit fraction (Hct) is a determinant for baseline cerebral blood flow (CBF) and between-subject variation of Hct thus causes variation in task-based BOLD fMRI signal changes. We first verified in healthy volunteers (n = 12) that Hct values can be derived reliably from venous blood T1 values by comparison with the conventional lab test. Together with CBF measured using phase-contrast MRI, this noninvasive estimation of Hct, instead of using a population-averaged Hct value, enabled more individual determination of oxygen delivery (DO2 ), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2 ). The inverse correlation of CBF and Hct explained about 80% of between-subject variation of CBF in this relatively uniform cohort of subjects, as expected based on the regulation of DO2 to maintain constant CMRO2 . Furthermore, we compared the relationships of visual task-evoked BOLD response with Hct and CBF. We showed that Hct and CBF contributed 22%-33% of variance in BOLD signal and removing the positive correlation with Hct and negative correlation with CBF allowed normalization of BOLD signal with 16%-22% lower variability. The results of this study suggest that adjustment for Hct effects is useful for studies of MRI perfusion and BOLD fMRI. Hum Brain Mapp 39:344-353, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Feng Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Developing Brain Research Lab, Children's National Medical Center, Washington DC, Washington
| | - Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Peiying Liu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Jun Hua
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - John J Strouse
- Division of Hematology, Department of Medicine, Duke University, Durham, North Carolina
| | - James J Pekar
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
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14
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Li W, Xu F, Schär M, Liu J, Shin T, Zhao Y, van Zijl PCM, Wasserman BA, Qiao Y, Qin Q. Whole-brain arteriography and venography: Using improved velocity-selective saturation pulse trains. Magn Reson Med 2017; 79:2014-2023. [PMID: 28799210 DOI: 10.1002/mrm.26864] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/21/2017] [Accepted: 07/15/2017] [Indexed: 11/07/2022]
Abstract
PURPOSE To develop velocity-selective (VS) MR angiography (MRA) protocols for arteriography and venography with whole-brain coverage. METHODS Tissue suppression using velocity-selective saturation (VSS) pulse trains is sensitive to radiofrequency field (B1 +) inhomogeneity. To reduce its sensitivity, we replaced the low-flip-angle hard pulses in the VSS pulse train with optimal composite (OCP) pulses. Additionally, new pulse sequences for arteriography and venography were developed by placing spatially selective inversion pulses with a delay to null signals from either venous or arterial blood. The VS MRA techniques were compared to the time-of-flight (TOF) MRA in six healthy subjects and two patients at 3T. RESULTS More uniform suppression of stationary tissue was observed when the hard pulses were replaced by OCP pulses in the VSS pulse trains, which improved contrast ratios between blood vessels and tissue background for both arteries (0.87 vs. 0.77) and veins (0.80 vs. 0.59). Both arteriograms and venograms depicted all major cervical and intracranial arteries and veins, respectively. Compared to TOF MRA, VS MRA not only offers larger spatial coverage but also depicts more small vessels. Initial clinical feasibility was shown in two patients with comparisons to TOF protocols. CONCLUSION Noncontrast-enhanced whole-brain arteriography and venography can be obtained without losing sensitivity to small vessel detection. Magn Reson Med 79:2014-2023, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Feng Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.,Developing Brain Research Lab, Children's National Medical Center, Washington, DC, USA
| | - Michael Schär
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jing Liu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Radiology, Guizhou Medical University Affiliated Hospital, Guiyang, Guizhou Province, China
| | - Taehoon Shin
- Division of Mechanical and Biomedical Engineering, Ewha Womans University, Seoul, South Korea.,Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, Maryland, USA
| | | | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Bruce A Wasserman
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Ye Qiao
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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15
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Li W, Liu P, Lu H, Strouse JJ, van Zijl PC, Qin Q. Fast measurement of blood T 1 in the human carotid artery at 3T: Accuracy, precision, and reproducibility. Magn Reson Med 2017; 77:2296-2302. [PMID: 27436420 PMCID: PMC5250597 DOI: 10.1002/mrm.26325] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/16/2016] [Accepted: 06/07/2016] [Indexed: 11/10/2022]
Abstract
PURPOSE To develop a fast protocol for measuring T1 values in the internal carotid artery (ICA), to validate this technique with in vitro measurements, and to evaluate its reproducibility. METHODS A modified Look-Locker sequence was optimized to enable rapid determination of T1 in the ICA at 3T. T1 values from the ICA were compared with in vitro measurements on individually sampled venous blood oxygenated to arterial levels. A test-retest reproducibility study was also conducted. RESULTS The group-averaged arterial blood T1 value was 1908 ± 77 ms for six women (hematocrit = 0.39 ± 0.03) and 1785 ± 55 ms for seven men (hematocrit = 0.45 ± 0.02), which is 100-200 ms longer than the widely adopted value obtained from bovine blood experiments. The arterial T1 value per subject correlated significantly with individual hematocrit values. The intrasession and intersession coefficients of variation were 1.1% and 2.1%, respectively, indicating good precision and reproducibility of our method. Reasonable agreement was observed between the in vivo and in vitro results with a correlation coefficient of 0.78. CONCLUSION The proposed method can provide fast arterial T1 measurement on individual subjects. When not performing such a subject-specific measurement, we recommend the use of 1908 ms and 1785 ms for healthy women and men, respectively, or 1841 ms for adults in general. Magn Reson Med 77:2296-2302, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Wenbo Li
- Department of Radiology; Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Peiying Liu
- Department of Radiology; Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- Department of Radiology; Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - John J. Strouse
- Division of Pediatric Hematology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter C.M. van Zijl
- Department of Radiology; Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Qin Qin
- Department of Radiology; Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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16
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Portnoy S, Seed M, Sled JG, Macgowan CK. Non-invasive evaluation of blood oxygen saturation and hematocrit from T 1 and T 2 relaxation times: In-vitro validation in fetal blood. Magn Reson Med 2017; 78:2352-2359. [PMID: 28191646 DOI: 10.1002/mrm.26599] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 11/17/2016] [Accepted: 12/13/2016] [Indexed: 01/24/2023]
Abstract
PURPOSE We propose an analytical method for calculating blood hematocrit (Hct) and oxygen saturation (sO2 ) from measurements of its T1 and T2 relaxation times. THEORY Through algebraic substitution, established two-compartment relationships describing R1=T1-1 and R2=T2-1 as a function of hematocrit and oxygen saturation were rearranged to solve for Hct and sO2 in terms of R1 and R2 . Resulting solutions for Hct and sO2 are the roots of cubic polynomials. METHODS Feasibility of the method was established by comparison of Hct and sO2 estimates obtained from relaxometry measurements (at 1.5 Tesla) in cord blood specimens to ground-truth values obtained by blood gas analysis. Monte Carlo simulations were also conducted to assess the effect of T1 , T2 measurement uncertainty on precision of Hct and sO2 estimates. RESULTS Good agreement was observed between estimated and ground-truth blood properties (bias = 0.01; 95% limits of agreement = ±0.13 for Hct and sO2 ). Considering the combined effects of biological variability and random measurement noise, we estimate a typical uncertainty of ±0.1 for Hct, sO2 estimates. CONCLUSION Results demonstrate accurate quantification of Hct and sO2 from T1 and T2 . This method is applicable to noninvasive fetal vessel oximetry-an application where existing oximetry devices are unusable or require risky blood-sampling procedures. Magn Reson Med 78:2352-2359, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Sharon Portnoy
- University of Toronto, Department of Medical Biophysics, Toronto, Canada.,Mouse Imaging Centre, Hospital for Sick Children, Toronto, Canada
| | - Mike Seed
- Hospital for Sick Children, Division of Cardiology, Toronto, Canada.,University of Toronto, Department of Pediatrics and Diagnostic Imaging, Toronto, Canada
| | - John G Sled
- University of Toronto, Department of Medical Biophysics, Toronto, Canada.,Mouse Imaging Centre, Hospital for Sick Children, Toronto, Canada.,University of Toronto, Department of Obstetrics and Gynecology, Toronto, Canada
| | - Christopher K Macgowan
- University of Toronto, Department of Medical Biophysics, Toronto, Canada.,Hospital for Sick Children, Department of Physiology and Experimental Medicine, Toronto, Canada
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17
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Grgac K, Li W, Huang A, Qin Q, van Zijl PCM. Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities. Magn Reson Imaging 2016; 38:234-249. [PMID: 27993533 DOI: 10.1016/j.mri.2016.12.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 12/12/2016] [Indexed: 11/16/2022]
Abstract
Blood is a physiological substance with multiple water compartments, which contain water-binding proteins such as hemoglobin in erythrocytes and albumin in plasma. Knowing the water transverse (R2) relaxation rates from these different blood compartments is a prerequisite for quantifying the blood oxygenation level-dependent (BOLD) effect. Here, we report the Carr-Purcell-Meiboom-Gill (CPMG) based transverse (R2CPMG) relaxation rates of water in bovine blood samples circulated in a perfusion system at physiological temperature in order to mimic blood perfusion in humans. R2CPMG values of blood plasma, lysed packed erythrocytes, lysed plasma/erythrocyte mixtures, and whole blood at 3 T, 7 T, 9.4 T, 11.7 T and 16.4 T were measured as a function of hematocrit or hemoglobin concentration, oxygenation, and CPMG inter-echo spacing (τcp). R2CPMG in lysed cells showed a small τcp dependence, attributed to the water exchange rate between free and hemoglobin-bound water to be much faster than τcp. This was contrary to the tangential dependence in whole blood, where a much slower exchange between cells and blood plasma applies. Whole blood data were fitted as a function of τcp using a general tangential correlation time model applicable for exchange as well as diffusion contributions to R2CPMG, and the intercept R20blood at infinitely short τcp was determined. The R20blood values at different hematocrit and the R2CPMG values of lysed erythrocyte/plasma mixtures at different hemoglobin concentration were used to determine the relaxivity of hemoglobin inside the erythrocyte (r2Hb) and albumin (r2Alb) in plasma. The r2Hb values obtained from lysed erythrocytes and whole blood were comparable at full oxygenation. However, while r2Hb determined from lysed cells showed a linear dependence on oxygenation, this dependence became quadratic in whole blood. This possibly suggests an additional relaxation effect inside intact cells, perhaps due to hemoglobin proximity to the erythrocyte membrane. However, we cannot exclude that this is a consequence of the simple tangential model used to remove relaxation contributions from exchange and diffusion. The extensive data set presented should be useful for future theory development for the transverse relaxation of blood.
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Affiliation(s)
- Ksenija Grgac
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Alan Huang
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
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18
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Abstract
Nuclear magnetic resonance relaxometry is a uniquely practical and versatile implementation of NMR technology. Because it does not depend on chemical shift resolution, it can be performed using low-field compact instruments deployed in atypical settings. Early relaxometry studies of human blood were focused on developing a diagnostic test for cancer. Those efforts were misplaced, as the measurements were not specific to cancer. However, important lessons were learned about the factors that drive the water longitudinal (T1) and transverse (T2) relaxation times. One key factor is the overall distribution of proteins and lipoproteins. Plasma water T2 can detect shifts in the blood proteome resulting from inflammation, insulin resistance and dyslipidemia. In whole blood, T2 is sensitive to hemoglobin content and oxygenation, although the latter can be suppressed by manipulating the static and applied magnetic fields. Current applications of compact NMR relaxometry include blood tests for candidiasis, hemostasis, malaria and insulin resistance.
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Affiliation(s)
- David P. Cistola
- Nanoparticle Diagnostics Laboratory, Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
- Departments of Clinical Laboratory Science and Biochemistry & Molecular Biology, College of Allied Health Sciences and Brody School of Medicine, East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, North Carolina 27834, USA
| | - Michelle D. Robinson
- Nanoparticle Diagnostics Laboratory, Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
- Departments of Clinical Laboratory Science and Biochemistry & Molecular Biology, College of Allied Health Sciences and Brody School of Medicine, East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, North Carolina 27834, USA
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19
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New frontiers in in vitro medical diagnostics by low field T2 magnetic resonance relaxometry. Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2016.02.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Wilson GJ, Springer CS, Bastawrous S, Maki JH. Human whole blood 1 H 2 O transverse relaxation with gadolinium-based contrast reagents: Magnetic susceptibility and transmembrane water exchange. Magn Reson Med 2016; 77:2015-2027. [PMID: 27297589 DOI: 10.1002/mrm.26284] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/31/2016] [Accepted: 04/29/2016] [Indexed: 02/02/2023]
Abstract
PURPOSE To characterize transverse relaxation in oxygenated whole blood with extracellular gadolinium-based contrast reagents by experiment and simulation. METHODS Experimental measurements of transverse 1 H2 O relaxation from oxygenated whole human blood and plasma were made at 1.5 and 3.0 Tesla. Spin-echo refocused and free-induction decays are reported for blood and plasma samples containing four different contrast reagents (gadobenate, gadoteridol, gadofosveset, and gadobutrol), each present at concentrations ranging from 1 to 18 mM (i.e., mmol (contrast reagent (CR))/L (blood)). Monte Carlo simulations were conducted to ascertain the molecular mechanisms underlying relaxation. These consisted of random walks of water molecules in a large ensemble of randomly oriented erythrocytes. Bulk magnetic susceptibility (BMS) differences between the extra- and intracellular compartments were taken into account. All key parameters for these simulations were taken from independent published measurements: they include no adjustable variables. RESULTS Transverse relaxation is much more rapid in whole blood than in plasma, and the large majority of this dephasing is reversible by spin echo. Agreement between the experimental data and simulated results is remarkably good. CONCLUSION Extracellular field inhomogeneities alone make very small contributions, whereas the orientation-dependent BMS intracellular resonance frequencies lead to the majority of transverse dephasing. Equilibrium exchange of water molecules between the intra- and extracellular compartments plays a significant role in transverse dephasing. Magn Reson Med 77:2015-2027, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
| | - Charles S Springer
- Advanced Imaging Research Center, Oregon Health and Science University, Portland, Oregon, USA
| | - Sarah Bastawrous
- Radiology, University of Washington, Seattle, Washington, USA.,Radiology, Puget Sound VA Healthcare System, Seattle, Washington, USA
| | - Jeffrey H Maki
- Radiology, University of Washington, Seattle, Washington, USA
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21
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Gho SM, Shin J, Kim MO, Kim DH. Simultaneous quantitative mapping of conductivity and susceptibility using a double-echo ultrashort echo time sequence: Example using a hematoma evolution study. Magn Reson Med 2015; 76:214-21. [DOI: 10.1002/mrm.25869] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 06/23/2015] [Accepted: 07/14/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Sung-Min Gho
- Department of Electrical and Electronic Engineering; Institute of BioMed-IT, Energy-IT and Smart-IT Technology, Yonsei University; Seoul Republic of Korea
| | - Jaewook Shin
- Department of Electrical and Electronic Engineering; Yonsei University; Seoul Republic of Korea
| | - Min-Oh Kim
- Department of Electrical and Electronic Engineering; Yonsei University; Seoul Republic of Korea
| | - Dong-Hyun Kim
- Department of Electrical and Electronic Engineering; Yonsei University; Seoul Republic of Korea
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22
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Li W, Grgac K, Huang A, Yadav N, Qin Q, van Zijl PCM. Quantitative theory for the longitudinal relaxation time of blood water. Magn Reson Med 2015; 76:270-81. [PMID: 26285144 DOI: 10.1002/mrm.25875] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/08/2015] [Accepted: 07/16/2015] [Indexed: 11/06/2022]
Abstract
PURPOSE To propose and evaluate a model for the blood water T1 that takes into account the effects of hematocrit fraction, oxygenation fraction, erythrocyte hemoglobin concentration, methemoglobin fraction, and plasma albumin concentration. METHODS Whole blood and lysed blood T1 data were acquired at magnetic fields of 3 Tesla (T), 7T, 9.4T, and 11.7T using inversion-recovery measurements and a home-built blood circulation system for maintaining physiological conditions. A quantitative model was derived based on multivariable fitting of this data. RESULTS Fitting of the model to the data allowed determination of the different parameters describing the blood water T1 such as those for the diamagnetic and paramagnetic effects of albumin and hemoglobin, and the contribution of methemoglobin. The model correctly predicts blood T1 at multiple fields, as verified by comparison with existing literature. CONCLUSION The model provides physical and physiological parameters describing the effects of hematocrit fraction, oxygenation, hemoglobin concentration, methemoglobin fraction, and albumin concentration on blood water T1 . It can be used to predict blood T1 at multiple fields. Magn Reson Med 76:270-281, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Wenbo Li
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Ksenija Grgac
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Alan Huang
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.,Philips Healthcare, Best, The Netherlands
| | - Nirbhay Yadav
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Qin Qin
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Peter C M van Zijl
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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23
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Ghanouni P, Pauly KB, Elias WJ, Henderson J, Sheehan J, Monteith S, Wintermark M. Transcranial MRI-Guided Focused Ultrasound: A Review of the Technologic and Neurologic Applications. AJR Am J Roentgenol 2015; 205:150-9. [PMID: 26102394 PMCID: PMC4687492 DOI: 10.2214/ajr.14.13632] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE This article reviews the physical principles of MRI-guided focused ultra-sound and discusses current and potential applications of this exciting technology. CONCLUSION MRI-guided focused ultrasound is a new minimally invasive method of targeted tissue thermal ablation that may be of use to treat central neuropathic pain, essential tremor, Parkinson tremor, and brain tumors. The system has also been used to temporarily disrupt the blood-brain barrier to allow targeted drug delivery to brain tumors.
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Affiliation(s)
- Pejman Ghanouni
- Stanford University, Department of Radiology, Division of Body MRI, Stanford, CA
| | - Kim Butts Pauly
- Stanford University, Departments of Radiology and Electrical Engineering and Bioengineering, Stanford, CA
| | - W. Jeff Elias
- University of Virginia, Department of Neurosurgery, Charlottesville, VA
| | - Jaimie Henderson
- Stanford University, Department of Neurosurgery and Neurology and Neurological Sciences, Stanford, CA
| | - Jason Sheehan
- University of Virginia, Department of Neurosurgery, Charlottesville, VA
| | | | - Max Wintermark
- Stanford University, Department of Radiology, Division of Neuroradiology, Stanford, CA
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24
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Sheng M, Lu H, Liu P, Thomas BP, McAdams CJ. Cerebral perfusion differences in women currently with and recovered from anorexia nervosa. Psychiatry Res 2015; 232:175-83. [PMID: 25795596 PMCID: PMC4417098 DOI: 10.1016/j.pscychresns.2015.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 12/19/2014] [Accepted: 02/19/2015] [Indexed: 12/26/2022]
Abstract
Anorexia nervosa is a serious psychiatric disorder characterized by restricted eating, a pursuit of thinness, and altered perceptions of body shape and size. Neuroimaging in anorexia nervosa has revealed morphological and functional alterations in the brain. A better understanding of physiological changes in anorexia nervosa could provide a brain-specific health marker relevant to treatment and outcomes. In this study, we applied several advanced magnetic resonance imaging (MRI) techniques to quantify regional and global cerebral blood flow (CBF) in 25 healthy women (HC), 23 patients currently with anorexia (AN-C) and 19 patients in long-term weight recovery following anorexia (AN-WR). Specifically, CBF was measured with pseudo-continuous arterial spin labeling (pCASL) MRI and then verified by a different technique, phase contrast (PC) MRI. Venous T2 values were determined by T2 relaxation under spin tagging (TRUST) MRI, and were used to corroborate the CBF results. These novel techniques were implemented on a standard 3T MRI scanner without any exogenous tracers, and the total scan duration was less than 10min. Voxel-wise comparison revealed that the AN-WR group showed lower CBF in bilateral temporal and frontal lobes than the AN-C group. Compared with the HC group, the AN-C group also showed higher CBF in the right temporal lobe. Whole-brain-averaged CBF was significantly decreased in the AN-WR group compared with the AN-C group, consistent with the PC-MRI results. Venous T2 values were lower in the AN-WR group than in the AN-C group, consistent with the CBF results. A review of prior work examining CBF in anorexia nervosa is included in the discussion. This study identifies several differences in the cerebral physiological alterations in anorexia nervosa, and finds specific differences relevant to the current state of the disorder.
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Affiliation(s)
- Min Sheng
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Hanzhang Lu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States,Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Peiying Liu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States,Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Binu P. Thomas
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Carrie J. McAdams
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, United States,Corresponding author. Tel: +1 214 648 4145; fax: +1 214 648 5321. (C.J.McAdams)
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Kauppinen RA. Multiparametric magnetic resonance imaging of acute experimental brain ischaemia. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2014; 80:12-25. [PMID: 24924265 DOI: 10.1016/j.pnmrs.2014.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 05/07/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
Abstract
Ischaemia is a condition in which blood flow either drops to zero or proceeds at severely decreased levels that cannot supply sufficient oxidizable substrates to maintain energy metabolism in vivo. Brain, a highly oxidative organ, is particularly susceptible to ischaemia. Ischaemia leads to loss of consciousness in seconds and, if prolonged, permanent tissue damage is inevitable. Ischaemia primarily results in a collapse of cerebral energy state, followed by a series of subtle changes in anaerobic metabolism, ion and water homeostasis that eventually initiate destructive internal and external processes in brain tissue. (31)P and (1)H NMR spectroscopy were initially used to evaluate anaerobic metabolism in brain. However, since the early 1990s (1)H Magnetic Resonance Imaging (MRI), exploiting the nuclear magnetism of tissue water, has become the key method for assessment of ischaemic brain tissue. This article summarises multi-parametric (1)H MRI work that has exploited diffusion, relaxation and magnetisation transfer as 'contrasts' to image ischaemic brain in preclinical models for the first few hours, with a view to assessing evolution of ischaemia and tissue viability in a non-invasive manner.
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Affiliation(s)
- Risto A Kauppinen
- School of Experimental Psychology and Clinical Research and Imaging Centre, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.
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Skewis LR, Lebedeva T, Papkov V, Thayer EC, Massefski W, Cuker A, Nagaswami C, Litvinov RI, Kowalska MA, Rauova L, Poncz M, Weisel JW, Lowery TJ, Cines DB. T2 magnetic resonance: a diagnostic platform for studying integrated hemostasis in whole blood--proof of concept. Clin Chem 2014; 60:1174-82. [PMID: 24958814 DOI: 10.1373/clinchem.2014.223735] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Existing approaches for measuring hemostasis parameters require multiple platforms, can take hours to provide results, and generally require 1-25 mL of sample. We developed a diagnostic platform that allows comprehensive assessment of hemostatic parameters on a single instrument and provides results within 15 min using 0.04 mL of blood with minimal sample handling. METHODS T2 magnetic resonance (T2MR) was used to directly measure integrated reactions in whole blood samples by resolving multiple water relaxation times from distinct sample microenvironments. Clotting, clot contraction, and fibrinolysis stimulated by thrombin or tissue plasminogen activator, respectively, were measured. T2MR signals of clotting samples were compared with images produced by scanning electron microscopy and with standard reference methods for the following parameters: hematocrit, prothrombin time, clot strength, and platelet activity. RESULTS Application of T2MR methodology revealed conditions under which a unique T2MR signature appeared that corresponded with the formation of polyhedral erythrocytes, the dynamics and morphology of which are dependent on thrombin, fibrinogen, hematocrit, and platelet levels. We also showed that the T2MR platform can be used for precise and accurate measurements of hematocrit (%CV, 4.8%, R(2) = 0.95), clotting time (%CV, 3.5%, R(2) = 0.94), clot strength (R(2) = 0.95), and platelet function (93% agreement with light transmission aggregometry). CONCLUSIONS This proof-of-concept study demonstrates that T2MR has the potential to provide rapid and sensitive identification of patients at risk for thrombosis or bleeding and to identify new biomarkers and therapeutic targets with a single, simple-to-employ analytic approach that may be suitable for routine use in both research and diverse clinical settings.
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Affiliation(s)
| | - Tatiana Lebedeva
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | | | | | | | - Adam Cuker
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Chandrasekaran Nagaswami
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Rustem I Litvinov
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - M Anna Kowalska
- Institute of Medical Biology, Polish Academy of Science, Lodz, Poland; Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | - Lubica Rauova
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | - Mortimer Poncz
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | - John W Weisel
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | | | - Douglas B Cines
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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Yablonskiy DA, Sukstanskii AL, He X. Blood oxygenation level-dependent (BOLD)-based techniques for the quantification of brain hemodynamic and metabolic properties - theoretical models and experimental approaches. NMR IN BIOMEDICINE 2013; 26:963-86. [PMID: 22927123 PMCID: PMC3510357 DOI: 10.1002/nbm.2839] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 06/19/2012] [Accepted: 06/22/2012] [Indexed: 05/06/2023]
Abstract
The quantitative evaluation of brain hemodynamics and metabolism, particularly the relationship between brain function and oxygen utilization, is important for the understanding of normal human brain operation, as well as the pathophysiology of neurological disorders. It can also be of great importance for the evaluation of hypoxia within tumors of the brain and other organs. A fundamental discovery by Ogawa and coworkers of the blood oxygenation level-dependent (BOLD) contrast opened up the possibility to use this effect to study brain hemodynamic and metabolic properties by means of MRI measurements. Such measurements require the development of theoretical models connecting the MRI signal to brain structure and function, and the design of experimental techniques allowing MR measurements to be made of the salient features of theoretical models. In this review, we discuss several such theoretical models and experimental methods for the quantification of brain hemodynamic and metabolic properties. The review's main focus is on methods for the evaluation of the oxygen extraction fraction (OEF) based on the measurement of the blood oxygenation level. A combination of the measurement of OEF and the cerebral blood flow (CBF) allows an evaluation to be made of the cerebral metabolic rate of oxygen consumption (CMRO2 ). We first consider in detail the magnetic properties of blood - magnetic susceptibility, MR relaxation and theoretical models of the intravascular contribution to the MR signal under different experimental conditions. We then describe a 'through-space' effect - the influence of inhomogeneous magnetic fields, created in the extravascular space by intravascular deoxygenated blood, on the formation of the MR signal. Further, we describe several experimental techniques taking advantage of these theoretical models. Some of these techniques - MR susceptometry and T2 -based quantification of OEF - utilize the intravascular MR signal. Another technique - quantitative BOLD - evaluates OEF by making use of through-space effects. In this review, we target both scientists just entering the MR field and more experienced MR researchers interested in the application of advanced BOLD-based techniques to the study of the brain in health and disease.
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Grgac K, van Zijl PCM, Qin Q. Hematocrit and oxygenation dependence of blood (1)H(2)O T(1) at 7 Tesla. Magn Reson Med 2012; 70:1153-9. [PMID: 23169066 DOI: 10.1002/mrm.24547] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 08/29/2012] [Accepted: 10/05/2012] [Indexed: 11/11/2022]
Abstract
Knowledge of blood (1)H2O T1 is critical for perfusion-based quantification experiments such as arterial spin labeling and cerebral blood volume-weighted MRI using vascular space occupancy. The dependence of blood (1)H2O T1 on hematocrit fraction (Hct) and oxygen saturation fraction (Y) was determined at 7 T using in vitro bovine blood in a circulating system under physiological conditions. Blood (1)H2O R1 values for different conditions could be readily fitted using a two-compartment (erythrocyte and plasma) model, which are described by a monoexponential longitudinal relaxation rate constant dependence. It was found that T1 = 2171 ± 39 ms for Y = 1 (arterial blood) and 2010 ± 41 ms for Y = 0.6 (venous blood), for a typical Hct of 0.42. The blood (1)H2O T1 values in the normal physiological range (Hct from 0.35 to 0.45, and Y from 0.6 to 1.0) were determined to range from 1900 to 2300 ms. The influence of oxygen partial pressure (pO2) and the effect of plasma osmolality for different anticoagulants were also investigated. It is discussed why blood (1)H2O T1 values measured in vivo for human blood may be about 10-20% larger than found in vitro for bovine blood at the same field strength.
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Affiliation(s)
- Ksenija Grgac
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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Cai K, Shore A, Singh A, Haris M, Hiraki T, Waghray P, Reddy D, Greenberg JH, Reddy R. Blood oxygen level dependent angiography (BOLDangio) and its potential applications in cancer research. NMR IN BIOMEDICINE 2012; 25:1125-1132. [PMID: 22302557 PMCID: PMC3390450 DOI: 10.1002/nbm.2780] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 12/06/2011] [Accepted: 12/21/2011] [Indexed: 05/31/2023]
Abstract
Clinically, development of anti-angiogenic drugs for cancer therapy is pivotal. Longitudinal monitoring of tumour angiogenesis can help clinicians determine the effectiveness of anti-angiogenic therapy. Blood oxygen level dependent (BOLD) effect has been widely used for functional imaging and tumour oxygenation assessment. In this study, the BOLD effect is investigated under different levels of oxygen inhalation for the development of a novel angiographic MRI technique, blood oxygen level dependent angiography (BOLDangio). Under short-term (<10 min) generalized hypoxia induced by inhalation of 8% oxygen, we measure BOLD contrast as high as 25% from vessels at 9.4T using a simple gradient echo (GRE) pulse sequence. This produces high-resolution 2D and 3D maps of normal and tumour brain vasculature in less than 10 minutes. Additionally, this technique reliably detects metastatic tumours and tumour-induced intracranial hemorrhage. BOLDangio provides a sensitive research tool for MRI of vasculature under normal and pathological conditions. Thus, it may be applied as a simple monitoring technique for measuring the effectiveness of anti-angiogenic drugs in a preclinical environment.
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Affiliation(s)
- Kejia Cai
- Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.
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30
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Ge Y, Zhang Z, Lu H, Tang L, Jaggi H, Herbert J, Babb JS, Rusinek H, Grossman RI. Characterizing brain oxygen metabolism in patients with multiple sclerosis with T2-relaxation-under-spin-tagging MRI. J Cereb Blood Flow Metab 2012; 32:403-12. [PMID: 22252237 PMCID: PMC3293125 DOI: 10.1038/jcbfm.2011.191] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this study, venous oxygen saturation and oxygen metabolic changes in multiple sclerosis (MS) patients were assessed using a recently developed T2-relaxation-under-spin-tagging (TRUST) magnetic resonance imaging (MRI), which measures the superior sagittal venous sinus blood oxygenation (Yv) and cerebral metabolic rate of oxygen (CMRO(2)), an index of global oxygen consumption. Thirty patients with relapsing-remitting MS and 30 age-matched healthy controls were studied using TRUST at 3 T MR. The mean expanded disability status scale (EDSS) of the patients was 2.3 (range, 0 to 5.5). We found significantly increased Yv (P<0.0001) and decreased CMRO(2) (P=0.003) in MS patients (mean±s.d.: 65.9%±5.1% and 138.8±35.4 μmol per 100 g per minute) as compared with healthy control subjects (60.2%±4.0% and 180.2±24.8 μmol per 100 g per minute, respectively), implying decrease of oxygen consumption in MS. There was a significant positive correlation between Yv and EDSS and between Yv and lesion load in MS patients (n=30); on the contrary, there was a significant negative correlation between CMRO(2) and EDSS and between CMRO(2) and lesion load (n=12). There was no correlation between Yv and brain atrophy measures. This study showed preliminary evidence of the potential utility of TRUST in global oxygen metabolism. Our results of significant underutilization of oxygen in MS raise important questions regarding mitochondrial respiratory dysfunction and neurodegeneration of the disease.
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Affiliation(s)
- Yulin Ge
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, New York 10016, USA.
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SHIMADA K, NAGASAKA T, SHIDAHARA M, MACHIDA Y, TAMURA H. In vivo Measurement of Longitudinal Relaxation Time of Human Blood by Inversion-recovery Fast Gradient-echo MR Imaging at 3T. Magn Reson Med Sci 2012; 11:265-71. [DOI: 10.2463/mrms.11.265] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Hua J, Qin Q, Pekar JJ, van Zijl PCM. Measurement of absolute arterial cerebral blood volume in human brain without using a contrast agent. NMR IN BIOMEDICINE 2011; 24:1313-25. [PMID: 21608057 PMCID: PMC3192228 DOI: 10.1002/nbm.1693] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 11/26/2010] [Accepted: 01/19/2011] [Indexed: 05/26/2023]
Abstract
Arterial cerebral blood volume (CBV(a) ) is a vital indicator of tissue perfusion and vascular reactivity. We extended the recently developed inflow vascular-space-occupancy (iVASO) MRI technique, which uses spatially selective inversion to suppress the signal from blood flowing into a slice, with a control scan to measure absolute CBV(a) using cerebrospinal fluid (CSF) for signal normalization. Images were acquired at multiple blood nulling times to account for the heterogeneity of arterial transit times across the brain, from which both CBV(a) and arterial transit times were quantified. Arteriolar CBV(a) was determined separately by incorporating velocity-dependent bipolar crusher gradients. Gray matter (GM) CBV(a) values (n=11) were 2.04 ± 0.27 and 0.76 ± 0.17 ml blood/100 ml tissue without and with crusher gradients (b=1.8 s/mm(2) ), respectively. Arterial transit times were 671 ± 43 and 785 ± 69 ms, respectively. The arterial origin of the signal was validated by measuring its T(2) , which was within the arterial range. The proposed approach does not require exogenous contrast agent administration, and provides a non-invasive alternative to existing blood volume techniques for mapping absolute CBV(a) in studies of brain physiology and neurovascular diseases.
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Affiliation(s)
- Jun Hua
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD USA
| | - James J. Pekar
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD USA
| | - Peter C. M. van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD USA
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Durst C, Monteith S, Sheehan J, Moldovan K, Snell J, Eames M, Huerta T, Walker W, Viola F, Kassell N, Wintermark M. Optimal imaging of in vitro clot sonothrombolysis by MR-guided focused ultrasound. J Neuroimaging 2011; 23:187-91. [PMID: 22082153 DOI: 10.1111/j.1552-6569.2011.00662.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE As magnetic resonance-guided focused ultrasound (MRgFUS) sonothrombolysis relies on mechanical rather than thermal mechanisms to achieve clot lysis, thermometry is not useful for the intraoperative monitoring of clot breakdown by MRgFUS. Therefore, the purpose of this study was to evaluate the optimum imaging sequence for sonothrombolysis. METHODS In vitro blood drawn from 6 healthy volunteers was imaged using T1, T2 spin-echo, and T2 gradient-echo (GRE) sequences both before and after sonication using an Insightec ExAblate 4000 FUS transducer. Signal intensities of the three MR imaging sequences were measured and normalized to background signal for each time point. Representative samples of the pre- and postsonication clot were also sent to pathology for hematologic analysis. RESULTS After sonication, the clot in the treatment tube was fully lysed as evidenced by physical and hematologic evaluation. The difference between pre- and postsonicated normalized signal intensity ratios demonstrated statistical significance only on T2 and GRE sequences (P < .001). However, significant blooming artifact limited interpretation on all GRE images. CONCLUSION T2 is the most appropriate sequence for the evaluation of mechanical MRgFUS sonothrombolysis of an in vitro clot. These findings are consistent across the oxidative states of clot up to 48 hours.
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Affiliation(s)
- Christopher Durst
- Department of Radiology, University of Virginia, Charlottesville, VA, USA
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Jahnke C, Kozerke S, Schnackenburg B, Marx N, Paetsch I. Three-dimensional contrast-enhanced and non-contrast-enhanced cardiac magnetic resonance imaging for the assessment of myocardial ischemic reactions: the practice of looking deeply into the myocardium. J Nucl Cardiol 2011; 18:937-51. [PMID: 21567282 DOI: 10.1007/s12350-011-9391-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Cosima Jahnke
- Department of Cardiology, University Hospital RWTH Aachen, Pauwelsstrasse 30, 52074, Aachen, Germany.
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35
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Kuroiwa Y, Yamashita A, Miyati T, Furukoji E, Takahashi M, Azuma T, Sugimura H, Asanuma T, Tamura S, Kawai K, Asada Y. MR signal change in venous thrombus relates organizing process and thrombolytic response in rabbit. Magn Reson Imaging 2011; 29:975-84. [DOI: 10.1016/j.mri.2011.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 04/18/2011] [Accepted: 04/22/2011] [Indexed: 10/18/2022]
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KUROIWA Y, YAMASHITA A, NISHIHIRA K, SHIBATA Y, MATSUURA Y, MAEDA M, ASADA Y. Cardiac Rupture in Acute Myocardial Infarction: Post-mortem MR Imaging. Magn Reson Med Sci 2011; 10:255-8. [DOI: 10.2463/mrms.10.255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Varela M, Hajnal JV, Petersen ET, Golay X, Merchant N, Larkman DJ. A method for rapid in vivo measurement of blood T1. NMR IN BIOMEDICINE 2011; 24:80-8. [PMID: 20669148 DOI: 10.1002/nbm.1559] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present a technique to measure the longitudinal relaxation time constant of venous blood (T(1b) ) in vivo in a few seconds. The MRI sequence consists of a thick-slab adiabatic inversion, followed by a series of slice-selective excitations and single-shot echo planar imaging readouts. The time intervals between excitations were chosen so that blood in macroscopic vessels is fully refreshed between excitations, making the blood signal follow an unperturbed inversion recovery curve. Static tissue, which experiences the inversion and all excitation pulses, quickly reaches a steady state at a low signal as a result of partial saturation. This allows blood-filled voxels to be discriminated from those containing static tissue, and to be fitted voxel-by-voxel to a simple inversion recovery model. The sequence was tested on a flow phantom with the proposed method, yielding T(1) values consistent to within 3% of those obtained using a conventional inversion recovery sequence with a spin-echo readout. The method was applied to seven adult volunteers and 18 neonates. The blood T(1) of the neonates (1799 ± 206 ms; range, 1393-2035 ms) was found to be more variable than that of adults (1717 ± 39 ms; range, 1662-1779 ms). A linear correlation between the inverse of T(1b) and the haematocrit was established in 12 neonates (R(2) = 0.90).
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Affiliation(s)
- Marta Varela
- Imaging Sciences Department, MRC Clinical Sciences Centre, Imperial College London, London, UK
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Qin Q, Strouse JJ, van Zijl PCM. Fast measurement of blood T1 in the human jugular vein at 3 Tesla. Magn Reson Med 2010; 65:1297-304. [PMID: 21500258 DOI: 10.1002/mrm.22723] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 09/24/2010] [Accepted: 10/17/2010] [Indexed: 12/21/2022]
Abstract
Current T(1) values for blood at 3T largely came from in vitro studies on animal blood or freshly drawn human blood. Measurement of blood T(1) in vivo could provide more specific information, e.g., for individuals with abnormal blood composition. Here, blood T(1) at 3T was measured rapidly (<1 min) in the internal jugular vein using a fast inversion-recovery technique in which multiple inversion time can be acquired rapidly due to constant refreshing of blood. Multishot EPI acquisition with flow compensation yielded high resolution images with minimum partial volume effect. Results showed T(1) = 1852 ± 104 msec among 24 healthy adults, a value higher than for bovine blood phantoms (1584 msec at Hct of 42%). A second finding was that of a significant difference (P < 0.01) between men and women, namely T(1) = 1780 ± 89 msec (n = 12) and T(1) = 1924 ± 58 msec (n = 12), respectively. This difference in normal subjects is tentatively explained by the difference in Hct between genders. Interestingly, however, studies done on sickle cell anemia patients with much lower Hct (23 ± 3%, n = 10) revealed similar venous blood T(1) = 1924 ± 82 msec, indicating other possible physical influences affecting blood T(1).
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Affiliation(s)
- Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Qin Q, Grgac K, van Zijl PCM. Determination of whole-brain oxygen extraction fractions by fast measurement of blood T(2) in the jugular vein. Magn Reson Med 2010; 65:471-9. [PMID: 21264936 DOI: 10.1002/mrm.22556] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/27/2010] [Accepted: 06/16/2010] [Indexed: 11/10/2022]
Abstract
The oxygen extraction fraction of the brain reports on the balance between oxygen delivery and consumption and can be used to assess deviations in physiological homeostasis. This is relevant clinically as well as for calibrating blood oxygen level-dependent functional MRI responses. Oxygen extraction fraction is reflected in the arteriovenous difference in oxygen saturation fraction (Y(v) - Y(a) ), which can be determined from venous T(2) values when arterial oxygenation is known. A pulse sequence is presented that allows rapid measurement (<1 min) of blood T(2) s in the internal jugular vein. The technique combines slice-saturation and blood inflow to attain high signal-to-noise ratio in blood and minimal contamination from tissue. The sequence is sensitized to T(2) using a nonselective Carr-Purcell-Meiboom-Gill T(2) preparation directly after slice saturation. Fast scanning (pulse repetition time of about 2 sec) is possible by using a nonselective saturation directly after acquisition to rapidly achieve steady-state longitudinal magnetization. The venous T(2) (for 10 msec Carr-Purcell-Meiboom-Gill interecho time) for normal volunteers was 62.4 ± 6.1 msec (n = 20). A calibration curve relating T(2) to blood oxygenation was established using a blood perfusion phantom. Using this calibration, a whole-brain oxygen extraction fraction of 0.37 ± 0.04 was determined (n = 20), in excellent agreement with literature values.
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Affiliation(s)
- Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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40
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Gardener AG, Francis ST, Prior M, Peters A, Gowland PA. Dependence of blood R2 relaxivity on CPMG echo-spacing at 2.35 and 7 T. Magn Reson Med 2010; 64:967-74. [DOI: 10.1002/mrm.22575] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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41
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BOLD fMRI using a modified HASTE sequence. Neuroimage 2009; 49:457-66. [PMID: 19643187 DOI: 10.1016/j.neuroimage.2009.07.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 07/16/2009] [Accepted: 07/17/2009] [Indexed: 11/21/2022] Open
Abstract
For more than a decade, turbo spin echo (TSE) pulse sequences have been suggested as an alternative to echo planar imaging (EPI) sequences for fMRI studies. Recent development in parallel imaging has renewed the interest in developing more robust TSE sequences for fMRI. In this study, a modified half Fourier acquisition single-shot TSE (mHASTE) sequence has been developed with a three-fold GRAPPA to improve temporal resolution as well as a preparation time to enhance BOLD sensitivity. Using a classical flashing checkerboard block design, the BOLD signal characteristics of this novel method have been systematically analyzed as a function of several sequence parameters and compared to those of gradient-echo and spin-echo EPI sequences. Experimental studies on visual cortex of five volunteers have provided evidence suggesting that mHASTE can be more sensitive to extra-vascular BOLD effects around microvascular networks, which leads to more accurate function localization. The studies also show that the activation cluster size in mHASTE increases with the refocusing RF flip angle and TE while decreasing with the echo number (n(center)) used to sample the k-space center. Compared to spin-echo EPI, mHASTE incurs an approximately 50% reduction in activation cluster size and an approximately 20% decrease in BOLD contrast. However a higher signal-to-noise ratio and a spatially more uniform temporal stability have been observed in mHASTE as compared to the EPI sequences when the scan times are held constant. With further refinement and optimization, mHASTE can become a viable alternative for fMRI in situations where the conventional EPI sequences are limited or prohibitive.
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42
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Blockley NP, Jiang L, Gardener AG, Ludman CN, Francis ST, Gowland PA. Field strength dependence of R1 and R2* relaxivities of human whole blood to ProHance, Vasovist, and deoxyhemoglobin. Magn Reson Med 2009; 60:1313-20. [PMID: 19030165 DOI: 10.1002/mrm.21792] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This study has measured the longitudinal and transverse (T2* relaxivity curves for ProHance (Gadoteridol), Vasovist (Gadofosveset) and deoxyhemoglobin at 1.5, 3.0, and 7.0 Tesla. The plots of R(1) versus both contrast agent and deoxyhemoglobin concentration were linear. The plots of R2* versus deoxyhemoglobin concentration showed a quadratic dependence. R2* versus contrast agent concentration showed a parabolic dependence with a minimum occurring at contrast agent concentrations of approximately 1.5 mM, corresponding to an accessible concentration in vivo. Monte Carlo simulations were performed to support the hypothesis that the minimum results from the susceptibility of the red blood cells being matched to the susceptibility of the plasma. Relaxivity values (s(-1)mM(-1)) for R2* and R1 for all agents and all three field strengths are given.
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Affiliation(s)
- N P Blockley
- Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom.
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43
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44
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Lu H, Ge Y. Quantitative evaluation of oxygenation in venous vessels using T2-Relaxation-Under-Spin-Tagging MRI. Magn Reson Med 2008; 60:357-63. [PMID: 18666116 DOI: 10.1002/mrm.21627] [Citation(s) in RCA: 272] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Noninvasive measurement of cerebral venous oxygenation can serve as a tool for better understanding fMRI signals and for clinical evaluation of brain oxygen homeostasis. In this study a novel technique, T2-Relaxation-Under-Spin-Tagging (TRUST) MRI, is developed to estimate oxygenation in venous vessels. This method uses the spin labeling principle to automatically isolate pure blood signals from which T2 relaxation times are determined using flow-insensitive T2-preparation pulses. The blood T2 is then converted to blood oxygenation using a calibration plot. In vivo experiments gave a baseline venous oxygenation of 64.8 +/- 6.3% in sagittal sinus in healthy volunteers (n = 24). Reproducibility studies demonstrated that the standard deviation across trials was 2.0 +/- 1.1%. The effects of repetition time and inversion time selections were investigated. The TRUST technique was further tested using various physiologic challenges. Hypercapnia induced an increase in venous oxygenation by 13.8 +/- 1.1%. On the other hand, caffeine ingestion resulted in a decrease in oxygenation by 7.0 +/- 1.8%. Contrast agent infusion (Gd-DTPA, 0.1 mmol/kg) reduced venous blood T2 by 11.2 ms. The results of this study show that TRUST MRI is a useful technique for quantitative assessment of blood oxygenation in the brain.
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Affiliation(s)
- Hanzhang Lu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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45
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Zhao JM, Clingman CS, Närväinen MJ, Kauppinen RA, van Zijl PCM. Oxygenation and hematocrit dependence of transverse relaxation rates of blood at 3T. Magn Reson Med 2007; 58:592-7. [PMID: 17763354 DOI: 10.1002/mrm.21342] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Knowledge of the transverse relaxation rates R2 and R2* of blood is relevant for quantitative assessment of functional MRI (fMRI) results, including calibration of blood oxygenation and measurement of tissue oxygen extraction fractions (OEFs). In a temperature controlled circulation system, these rates were measured for blood in vitro at 3T under conditions akin to the physiological state. Single spin echo (SE) and gradient echo (GRE) sequences were used to determine R2 and R2*, respectively. Both rates varied quadratically with deoxygenation, and changes in R2* were found to be due predominantly to changes in R2. These data were used to estimate intravascular blood oxygenation level dependent (BOLD) contributions during visual activation. Due to the large R2* in venous blood, intravascular SE BOLD signal changes were larger than GRE effects at echo times above 30 ms. When including extravascular effects to estimate the total BOLD effect, GRE BOLD dominated due to the large tissue volume fraction.
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Affiliation(s)
- Jason M Zhao
- Department of Radiology, Division of MRI Research, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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46
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Rooney WD, Johnson G, Li X, Cohen ER, Kim SG, Ugurbil K, Springer CS. Magnetic field and tissue dependencies of human brain longitudinal1H2O relaxation in vivo. Magn Reson Med 2007; 57:308-18. [PMID: 17260370 DOI: 10.1002/mrm.21122] [Citation(s) in RCA: 483] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Brain water proton (1H2O) longitudinal relaxation time constants (T1) were obtained from three healthy individuals at magnetic field strengths (B0) of 0.2 Tesla (T), 1.0T, 1.5T, 4.0T, and 7.0T. A 5-mm midventricular axial slice was sampled using a modified Look-Locker technique with 1.5 mm in-plane resolution, and 32 time points post-adiabatic inversion. The results confirmed that for most brain tissues, T1 values increased by more than a factor of 3 between 0.2T and 7T, and over this range were well fitted by T1 (s)=0.583(B0)0.382, T1(s)=0.857(B0)0.376, and T1(s)=1.35(B0)0.340 for white matter (WM), internal GM, and blood 1H2O, respectively. The ventricular cerebrospinal fluid (CSF) 1H2O T1 value did not change with B0, and its average value (standard deviation (SD)) across subjects and magnetic fields was 4.3 (+/-0.2) s. The tissue 1/T1 values at each field were well correlated with the macromolecular mass fraction, and to a lesser extent tissue iron content. The field-dependent increases in 1H2O T1 values more than offset the well-known decrease in typical MRI contrast reagent (CR) relaxivity, and simulations predict that this leads to lower CR concentration detection thresholds with increased magnetic field.
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Affiliation(s)
- William D Rooney
- Chemistry Department, Brookhaven National Laboratory, Upton, New York, USA.
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47
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Dobre MC, Uğurbil K, Marjanska M. Determination of blood longitudinal relaxation time (T1) at high magnetic field strengths. Magn Reson Imaging 2006; 25:733-5. [PMID: 17540286 DOI: 10.1016/j.mri.2006.10.020] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 10/28/2006] [Indexed: 11/19/2022]
Abstract
In this study, a circulation system was used to measure T(1) values of bovine blood under physiological conditions at field strengths of 4.7, 7 and 9.4 T. Results show that T(1) increases linearly with magnetic field B(0) and can be described with the equation T(1)=129 ms/T B(0)+1167 ms for magnetic field strengths between 1.5 and 9.4 T.
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Affiliation(s)
- Mircea C Dobre
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN 55455, USA
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48
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Thomas DL, Lythgoe MF, Gadian DG, Ordidge RJ. In vivo measurement of the longitudinal relaxation time of arterial blood (T1a) in the mouse using a pulsed arterial spin labeling approach. Magn Reson Med 2006; 55:943-7. [PMID: 16526019 DOI: 10.1002/mrm.20823] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel method for measuring the longitudinal relaxation time of arterial blood (T1a) is presented. Knowledge of T1a is essential for accurately quantifying cerebral perfusion using arterial spin labeling (ASL) techniques. The method is based on the flow-sensitive alternating inversion recovery (FAIR) pulsed ASL (PASL) approach. We modified the standard FAIR acquisition scheme by incorporating a global saturation pulse at the beginning of the recovery period. With this approach the FAIR tissue signal difference has a simple monoexponential dependence on the recovery time, with T1a as the time constant. Therefore, FAIR measurements performed over a range of recovery times can be fitted to a monoexponential recovery curve and T1a can be calculated directly. This eliminates many of the difficulties associated with the measurement of T1a. Experiments performed in vivo in the mouse at 2.35T produced a mean value of 1.51 s for T1a, consistent with previously published values.
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Affiliation(s)
- David L Thomas
- RCS Unit of Biophysics, Institute of Child Health, University College London, London, UK.
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49
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Strouse JJ, Cox CS, Melhem ER, Lu H, Kraut MA, Razumovsky A, Yohay K, van Zijl PC, Casella JF. Inverse correlation between cerebral blood flow measured by continuous arterial spin-labeling (CASL) MRI and neurocognitive function in children with sickle cell anemia (SCA). Blood 2006; 108:379-81. [PMID: 16537809 PMCID: PMC1482738 DOI: 10.1182/blood-2005-10-4029] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Overt stroke, clinically "silent" cerebral infarct, and neurocognitive impairment are frequent complications of sickle cell anemia (SCA). Current imaging techniques have limited sensitivity and specificity to identify children at risk for neurocognitive impairment. We prospectively evaluated 24 children with SCA with a neurologic exam, complete blood count, transcranial Doppler ultrasound (TCD), measurement of intelligence quotient (IQ), and magnetic resonance imaging (MRI) with measurement of cerebral blood flow (CBF) using continuous arterial spin-labeling (CASL) MRI. Average CBF to gray matter was 112 +/- 36 mL/100 g/min. We identified a strong inverse relationship between performance IQ and CBF (-1.5 points per 10 mL/100 g/min increase in CBF, P = .013). Elevated steady-state white blood cell count (> or = 14 x 10(9)/L [14,000/microL]) was associated with lower full scale IQ (86 +/- 9 vs 99 +/- 10, P = .005). CASL MRI may identify children with neurocognitive impairment, before damage is evident by structural MRI or TCD.
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Affiliation(s)
- John J Strouse
- Division of Pediatric Hematology, Department of Pediatrics, the Neurocirculatory Physiology Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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50
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Jin T, Zhao F, Kim SG. Sources of functional apparent diffusion coefficient changes investigated by diffusion-weighted spin-echo fMRI. Magn Reson Med 2006; 56:1283-92. [PMID: 17051530 DOI: 10.1002/mrm.21074] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The mechanism behind previously observed changes in the apparent diffusion coefficient (ADC) during brain activation is not well understood. Therefore, we investigated the signal source and spatial specificity of functional magnetic resonance imaging (fMRI) ADC changes systematically in the visual cortex of cats using diffusion-weighted (DW) spin-echo (SE) fMRI with b-values of 2, 200, and 800 s/mm(2), and echo times (TE) of 16, 28, and 60 ms at 9.4 T. For b > or = 200 s/mm(2), no ADC changes were detected in brain parenchyma, suggesting a minimal tissue contribution to the ADC change. For b < or = 200 s/mm(2), TE-dependent ADC increases were observed. When the venous blood contribution was minimized, the ADC change was higher at the middle cortical layer than at the cortical surface, which is mainly attributed to a functional elevation in arterial blood volume. At TE = 16 ms, the highest ADC changes occurred at the cortical surface with its large draining veins, which can mainly be explained by an additional contribution from the venous blood oxygenation changes. Our TE-dependent ADC results agree with computer simulations based on a three-compartment model. The contribution of arterial blood volume changes in ADC fMRI offers an improvement in spatial localization for SE-BOLD fMRI studies.
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Affiliation(s)
- Tao Jin
- Magnetic Resonance Research Center, Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15203, USA.
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