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Kaczmarz S, Hyder F, Preibisch C. Oxygen extraction fraction mapping with multi-parametric quantitative BOLD MRI: Reduced transverse relaxation bias using 3D-GraSE imaging. Neuroimage 2020; 220:117095. [PMID: 32599265 PMCID: PMC7730517 DOI: 10.1016/j.neuroimage.2020.117095] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 06/11/2020] [Accepted: 06/18/2020] [Indexed: 01/22/2023] Open
Abstract
Magnetic resonance imaging (MRI)-based quantification of the blood-oxygenation-level-dependent (BOLD) effect allows oxygen extraction fraction (OEF) mapping. The multi-parametric quantitative BOLD (mq-BOLD) technique facilitates relative OEF (rOEF) measurements with whole brain coverage in clinically applicable scan times. Mq-BOLD requires three separate scans of cerebral blood volume and transverse relaxation rates measured by gradient-echo (1/T2*) and spin-echo (1/T2). Although the current method is of clinical merit in patients with stroke, glioma and internal carotid artery stenosis (ICAS), there are relaxation measurement artefacts that impede the sensitivity of mq-BOLD and artificially elevate reported rOEF values. We posited that T2-related biases caused by slice refocusing imperfections during rapid 2D-GraSE (Gradient and Spin Echo) imaging can be reduced by applying 3D-GraSE imaging sequences, because the latter requires no slice selective pulses. The removal of T2-related biases would decrease overestimated rOEF values measured by mq-BOLD. We characterized effects of T2-related bias in mq-BOLD by comparing the initially employed 2D-GraSE and two proposed 3D-GraSE sequences to multiple single spin-echo reference measurements, both in vitro and in vivo. A phantom and 25 participants, including young and elderly healthy controls as well as ICAS-patients, were scanned. We additionally proposed a procedure to reliably identify and exclude artefact affected voxels. In the phantom, 3D-GraSE derived T2 values had 57% lower deviation from the reference. For in vivo scans, the formerly overestimated rOEF was reduced by −27% (p < 0.001). We obtained rOEF = 0.51, which is much closer to literature values from positron emission tomography (PET) measurements. Furthermore, increased sensitivity to a focal rOEF elevation in an ICAS-patient was demonstrated. In summary, the application of 3D-GraSE improves the mq-BOLD-based rOEF quantification while maintaining clinically feasible scan times. Thus, mq-BOLD with non-slice selective T2 imaging is highly promising to improve clinical diagnostics of cerebrovascular diseases such as ICAS.
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Affiliation(s)
- Stephan Kaczmarz
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Munich, Germany; Departments of Radiology & Biomedical Imaging and of Biomedical Engineering, Magnetic Resonance Research Center, Yale University, New Haven, CT, 06520, USA; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Munich, Germany.
| | - Fahmeed Hyder
- Departments of Radiology & Biomedical Imaging and of Biomedical Engineering, Magnetic Resonance Research Center, Yale University, New Haven, CT, 06520, USA
| | - Christine Preibisch
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Clinic for Neurology, Munich, Germany
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Balasubramanian M, Polimeni JR, Mulkern RV. In vivo measurements of irreversible and reversible transverse relaxation rates in human basal ganglia at 7 T: making inferences about the microscopic and mesoscopic structure of iron and calcification deposits. NMR IN BIOMEDICINE 2019; 32:e4140. [PMID: 31322331 PMCID: PMC6817385 DOI: 10.1002/nbm.4140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 05/29/2019] [Accepted: 06/12/2019] [Indexed: 05/24/2023]
Abstract
The goal of this study was to measure irreversible and reversible transverse relaxation rates in the globus pallidus and putamen at 7 T, and to use these rates to make inferences about the sub-voxel structure of iron and calcification deposits. Gradient Echo Sampling of a Spin Echo (GESSE) data were acquired at 7 T on eighteen volunteers spanning a large range of ages (23-85 years), with calcifications in the globus pallidus incidentally observed in one volunteer. Maps of transverse relaxation rates were derived from the GESSE data, and the mean value of these rates in globus pallidus and putamen was estimated for each volunteer. Both irreversible and reversible transverse relaxation rates increased with the expected age-dependent iron content in these structures, except for the individual with calcifications for whom extremely large reversible relaxation rates but normal irreversible relaxation rates were found in the globus pallidus. Given the sensitivity of irreversible and reversible transverse relaxation rates to microscopic and mesoscopic field variations, respectively, our findings suggest that joint consideration of these rates may yield information not only about the amount of iron and calcification deposited in the brain, but also about the sub-voxel structure of these deposits, perhaps revealing certain aspects of their geometry and cellular distribution.
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Affiliation(s)
- Mukund Balasubramanian
- Harvard Medical School, Boston, MA, USA
- Department of Radiology, Boston Children’s Hospital, Boston, MA, USA
| | - Jonathan R. Polimeni
- Harvard Medical School, Boston, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Robert V. Mulkern
- Harvard Medical School, Boston, MA, USA
- Department of Radiology, Boston Children’s Hospital, Boston, MA, USA
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Goede LL, Pflugrad H, Schmitz B, Lanfermann H, Tryc AB, Barg-Hock H, Klempnauer J, Weissenborn K, Ding XQ. Quantitative magnetic resonance imaging indicates brain tissue alterations in patients after liver transplantation. PLoS One 2019; 14:e0222934. [PMID: 31553760 PMCID: PMC6760889 DOI: 10.1371/journal.pone.0222934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To investigate cerebral microstructural alterations in patients treated with calcineurin inhibitors (CNI) after orthotopic liver transplantation (OLT) using quantitative magnetic resonance imaging (qMRI) and a cross-sectional study design. METHODS Cerebral qMRI was performed in 85 patients in a median 10 years after OLT compared to 31 healthy controls. Patients were treated with different dosages of CNI or with a CNI-free immunosuppression (CNI-free: n = 19; CNI-low: n = 36; CNI-standard: n = 30). T2-, T2*- and T2'- relaxation times, as well as apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in brain gray and white matter by using the regions of interest method. RESULTS In comparison to controls, patients revealed significantly increased T2, T2*, T2', ADC and reduced FA, predominantly in the frontal white matter, indicating microstructural brain alterations represented by increased free water (increased T2), reduced neuronal metabolism (increased T2') and a lower degree of spatial organization of the nervous fibers (reduced FA). CNI-low and CNI-free patients showed more alterations than CNI-standard patients. Analysis of their history revealed impairment of kidney function while under standard CNI dose suggesting that these patients may be more vulnerable to toxic CNI side-effects. CONCLUSION Our findings suggest that the individual sensitivity to toxic side effects should be considered when choosing an appropriate immunosuppressive regimen in patients after liver transplantation.
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Affiliation(s)
- Lukas Laurids Goede
- Department of Neurology, Hannover Medical School, Hannover, Germany
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
- Integrated Research and Treatment Centre Transplantation (IFB-Tx), Hannover Medical School, Hannover, Germany
| | - Henning Pflugrad
- Department of Neurology, Hannover Medical School, Hannover, Germany
- Integrated Research and Treatment Centre Transplantation (IFB-Tx), Hannover Medical School, Hannover, Germany
| | - Birte Schmitz
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - Heinrich Lanfermann
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - Anita Blanka Tryc
- Department of Neurology, Hannover Medical School, Hannover, Germany
- Integrated Research and Treatment Centre Transplantation (IFB-Tx), Hannover Medical School, Hannover, Germany
| | - Hannelore Barg-Hock
- Clinic for Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany
| | - Jürgen Klempnauer
- Clinic for Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany
| | - Karin Weissenborn
- Department of Neurology, Hannover Medical School, Hannover, Germany
- Integrated Research and Treatment Centre Transplantation (IFB-Tx), Hannover Medical School, Hannover, Germany
| | - Xiao-Qi Ding
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
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Hirase T, Ruff ES, Ratnani I, Surani SR. Impact of Conservative Versus Conventional Oxygenation on Outcomes of Patients in Intensive Care Units: A Systematic Review and Meta-analysis. Cureus 2019; 11:e5662. [PMID: 31720138 PMCID: PMC6823015 DOI: 10.7759/cureus.5662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 09/14/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND There is mixed evidence in the superiority of conservative versus conventional approach to oxygen therapy among patients admitted into the intensive care unit (ICU). The purpose of this study was to determine if conservative versus conventional oxygenation results in a statistically significant difference in outcomes in ICU patients. METHODS A systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO) and performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inclusion criteria consisted of Level I-IV investigations of conservative versus conventional oxygenation among ICU patients. ICU mortality, 28-day mortality, in-hospital mortality, ICU length-of-stay, hospital length-of-stay, rate of new infections, and rate of new non-respiratory organ failure were compared using two-sample Z-tests using p-value less than 0.05. RESULTS Three thousand four hundred thirty-three articles were screened. Four articles were included in the analysis. Three hundred seventy-two patients under the conservative oxygenation arm (Minimum target SpO2: 88-94%) and 370 patients under the conventional oxygenation arm (Minimum target SpO2: 96-97%) were analyzed. ICU mortality (16.7 ± 9.5% vs. 22.7 ± 6.0%; P<0.01), 28-day mortality (34.6 ± 26.4% vs. 41.6 ± 14.6%; P=0.02), and in-hospital mortality (30.2 ± 22.5% vs. 37.7 ± 14.2%; P<0.01) were all significantly lower in the conservative oxygenation arm versus the conventional oxygenation arm, respectively. Rate of new non-respiratory organ failure was also significantly lower in the conservative oxygenation arm (20.0 ± 8.5% vs. 29.7 ± 11.7%; P<0.01). CONCLUSION The authors conclude that conservative oxygenation therapy could result in significantly lower rates of ICU mortality, 28-day mortality, in-hospital mortality, and new-onset non-respiratory organ failure. Further randomized controlled studies that show clinical outcome improvement in multiple parameters may be worthwhile to assess the true efficacy of this practice.
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Affiliation(s)
- Takashi Hirase
- Orthopedics and Sports Medicine, Houston Methodist Hospital, Houston, USA
| | - Eric S Ruff
- Plastic Surgery, University of Texas Medical Branch, Galveston, USA
| | - Iqbal Ratnani
- Anesthesiology and Critical Care, Houston Methodist Hospital, Houston, USA
| | - Salim R Surani
- Internal Medicine, Texas A&M Health Science Center, Temple, USA
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Seiler A, Kammerer S, Gühl A, Schüre JR, Deichmann R, Nöth U, Pfeilschifter W, Hattingen E, Keese M, Pilatus U, Wagner M. Revascularization of High-Grade Carotid Stenosis Restores Global Cerebral Energy Metabolism. Stroke 2019; 50:1742-1750. [PMID: 31164069 DOI: 10.1161/strokeaha.118.023559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose- Chronic cerebral hemodynamic impairment due to high-grade occlusive carotid disease may lead to compromised energy metabolism. This might result in chronic subtle tissue damage, even in patients without overt brain infarction. The aim of this study was to investigate hypoperfusion-related changes of cerebral energy metabolism and their potential restitution after revascularization. For this purpose, 3-dimensional 31P magnetic resonance spectroscopy and oxygenation-sensitive T2' magnetic resonance imaging were used (with 1/T2'=1/T2*-1/T2), which were expected to cross-validate each other. Methods- Ten patients with unilateral high-grade carotid artery stenosis resulting in a transient ischemic attack or a nondisabling cerebral ischemia were included. Then, high-energy metabolites, intracellular pH, and oxygenation-sensitive quantitative (q)T2' values were determined in noninfarcted hypoperfused areas delineated on time-to-peak maps from perfusion-weighted imaging and in unaffected contralateral areas before and shortly after carotid stenting/endarterectomy. Repeated measures ANOVA was used to test for intervention effects. Results- Within dependent hypoperfused areas ipsilateral to the stenosis, qT2' was significantly decreased ( P<0.05) as compared to corresponding contralateral areas before carotid intervention. There was a significant effect of carotid intervention on qT2' values in both hemispheres ( P<0.001). No differences between hemispheres were found for qT2' after revascularization. Intracellular pH and qT2' values showed a significant negative relationship ( P=0.005) irrespective of time point and hemisphere. Conclusions- After revascularization of unilateral high-grade carotid stenosis, previously decreased qT2' in the dependent hypoperfused territory as marker of hypoxia reincreases not only in the dependent territory but also in corresponding contralateral brain tissue. This might indicate a restriction of the whole-brain oxygen metabolism in case of unilateral high-grade carotid stenosis and an improvement of whole-brain oxygenation after revascularization that goes beyond acute clinically apparent affection of the dependent territory. Furthermore, tissue oxygen supply seems to be closely linked to intracellular pH.
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Affiliation(s)
- Alexander Seiler
- From the Department of Neurology (A.S., W.P.), Goethe University Frankfurt, Germany
| | - Sara Kammerer
- Institute of Neuroradiology (S.K., A.G., J.R.S., E.H., U.P., M.W.), Goethe University Frankfurt, Germany
| | - Alexander Gühl
- Institute of Neuroradiology (S.K., A.G., J.R.S., E.H., U.P., M.W.), Goethe University Frankfurt, Germany
| | - Jan Rüdiger Schüre
- Institute of Neuroradiology (S.K., A.G., J.R.S., E.H., U.P., M.W.), Goethe University Frankfurt, Germany
| | - Ralf Deichmann
- Brain Imaging Center (R.D., U.N.), Goethe University Frankfurt, Germany
| | - Ulrike Nöth
- Brain Imaging Center (R.D., U.N.), Goethe University Frankfurt, Germany
| | | | - Elke Hattingen
- Institute of Neuroradiology (S.K., A.G., J.R.S., E.H., U.P., M.W.), Goethe University Frankfurt, Germany
| | - Michael Keese
- Department of Vascular Surgery (M.K.), Goethe University Frankfurt, Germany
| | - Ulrich Pilatus
- Institute of Neuroradiology (S.K., A.G., J.R.S., E.H., U.P., M.W.), Goethe University Frankfurt, Germany
| | - Marlies Wagner
- Institute of Neuroradiology (S.K., A.G., J.R.S., E.H., U.P., M.W.), Goethe University Frankfurt, Germany
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Seiler A, Blockley NP, Deichmann R, Nöth U, Singer OC, Chappell MA, Klein JC, Wagner M. The relationship between blood flow impairment and oxygen depletion in acute ischemic stroke imaged with magnetic resonance imaging. J Cereb Blood Flow Metab 2019; 39:454-465. [PMID: 28929836 PMCID: PMC6421246 DOI: 10.1177/0271678x17732448] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Oxygenation-sensitive spin relaxation time T2' and relaxation rate R2' (1/T2') are presumed to be markers of the cerebral oxygen extraction fraction (OEF) in acute ischemic stroke. In this study, we investigate the relationship of T2'/R2' with dynamic susceptibility contrast-based relative cerebral blood flow (rCBF) in acute ischemic stroke to assess their plausibility as surrogate markers of the ischemic penumbra. Twenty-one consecutive patients with internal carotid artery and/or middle cerebral artery occlusion were studied at 3.0 T. A physiological model of the cerebral vasculature (VM) was used to process PWI raw data in addition to a conventional deconvolution technique. T2', R2', and rCBF values were extracted from the ischemic core and hypoperfused areas. Within hypoperfused tissue, no correlation was found between deconvolved rCBF and T2' ( r = -0.05, p = 0.788), or R2' ( r = 0.039, p = 0.836). In contrast, we found a strong positive correlation with T2' ( r = 0.444, p = 0.006) and negative correlation with R2' ( r = -0.494, p = 0.0025) for rCBFVM, indicating increasing OEF with decreasing CBF and that rCBF based on the vascular model may be more closely related to metabolic disturbances. Further research to refine and validate these techniques may enable their use as MRI-based surrogate markers of the ischemic penumbra for selecting stroke patients for interventional treatment strategies.
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Affiliation(s)
- Alexander Seiler
- 1 Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany
| | - Nicholas P Blockley
- 2 Nuffield Department of Clinical Neurosciences, Oxford Center for Functional MRI of the Brain, University of Oxford, Oxford, UK
| | - Ralf Deichmann
- 3 Brain Imaging Center, Goethe University Frankfurt, Frankfurt, Germany
| | - Ulrike Nöth
- 3 Brain Imaging Center, Goethe University Frankfurt, Frankfurt, Germany
| | - Oliver C Singer
- 1 Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany
| | - Michael A Chappell
- 2 Nuffield Department of Clinical Neurosciences, Oxford Center for Functional MRI of the Brain, University of Oxford, Oxford, UK.,4 Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, UK
| | - Johannes C Klein
- 5 Nuffield Department of Clinical Neurosciences, Oxford University, and Department of Neurology, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Marlies Wagner
- 6 Institute of Neuroradiology, Goethe University Frankfurt, Frankfurt, Germany
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Seiler A, Deichmann R, Pfeilschifter W, Hattingen E, Singer OC, Wagner M. T2-Imaging to Assess Cerebral Oxygen Extraction Fraction in Carotid Occlusive Disease: Influence of Cerebral Autoregulation and Cerebral Blood Volume. PLoS One 2016; 11:e0161408. [PMID: 27560515 PMCID: PMC4999181 DOI: 10.1371/journal.pone.0161408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 08/04/2016] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Quantitative T2'-mapping detects regional changes of the relation of oxygenated and deoxygenated hemoglobin (Hb) by using their different magnetic properties in gradient echo imaging and might therefore be a surrogate marker of increased oxygen extraction fraction (OEF) in cerebral hypoperfusion. Since elevations of cerebral blood volume (CBV) with consecutive accumulation of Hb might also increase the fraction of deoxygenated Hb and, through this, decrease the T2'-values in these patients we evaluated the relationship between T2'-values and CBV in patients with unilateral high-grade large-artery stenosis. MATERIALS AND METHODS Data from 16 patients (13 male, 3 female; mean age 53 years) with unilateral symptomatic or asymptomatic high-grade internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis/occlusion were analyzed. MRI included perfusion-weighted imaging and high-resolution T2'-mapping. Representative relative (r)CBV-values were analyzed in areas of decreased T2' with different degrees of perfusion delay and compared to corresponding contralateral areas. RESULTS No significant elevations in cerebral rCBV were detected within areas with significantly decreased T2'-values. In contrast, rCBV was significantly decreased (p<0.05) in regions with severe perfusion delay and decreased T2'. Furthermore, no significant correlation between T2'- and rCBV-values was found. CONCLUSIONS rCBV is not significantly increased in areas of decreased T2' and in areas of restricted perfusion in patients with unilateral high-grade stenosis. Therefore, T2' should only be influenced by changes of oxygen metabolism, regarding our patient collective especially by an increase of the OEF. T2'-mapping is suitable to detect altered oxygen consumption in chronic cerebrovascular disease.
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Affiliation(s)
- Alexander Seiler
- Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany
- * E-mail:
| | - Ralf Deichmann
- Brain Imaging Center, Goethe University Frankfurt, Frankfurt, Germany
| | | | - Elke Hattingen
- Department of Neuroradiology, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Oliver C. Singer
- Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany
- Department of Neurology, Helios HSK Hospital, Wiesbaden, Germany
| | - Marlies Wagner
- Institute of Neuroradiology, Goethe University Frankfurt, Frankfurt, Germany
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Arterial Spin Labeling Techniques 2009-2014. J Med Imaging Radiat Sci 2016; 47:98-107. [PMID: 31047171 DOI: 10.1016/j.jmir.2015.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 07/03/2015] [Accepted: 08/18/2015] [Indexed: 12/23/2022]
Abstract
PURPOSE Arterial spin labeling (ASL) techniques have been implemented across a diverse range of clinical and experimental applications. This review aims to evaluate the current feasibility of ASL in clinical neuroradiology based on recent improvements to ASL sequences and highlight areas for potential clinical applications. METHODS AND MATERIALS In December 2014, a literature search was conducted on PubMed Central, EMBASE, and Scopus using the search terms: "arterial spin labeling, neuroradiology," for studies published between 2009 and 2014 (inclusive). Of 483 studies matching the inclusion criteria, the number of studies using continuous, pseudocontinuous, pulsed, and velocity-selective ASL sequences was 42, 209, 226, and 3, respectively. Studies were classified based on several common clinical applications according to the type of ASL sequence used. Studies using pulsed ASL and pseudo-continuous ASL were grouped based on common sequences. RESULTS The number of clinical studies was 264. Numerous studies applied ASL to stroke management (43 studies), drug testing (21 studies), neurodegenerative diseases (40 studies), and psychiatric disorders (26 studies). CONCLUSIONS This review discusses several factors hindering the implementation of clinical ASL and ASL-related radiofrequency safety issues encountered in clinical practice. However, a limited number of search terms were used. Further development of robust sequences with multislice imaging capabilities and reduced radiofrequency energy deposition will hopefully improve the clinical acceptance of ASL.
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Eylers VV, Maudsley AA, Bronzlik P, Dellani PR, Lanfermann H, Ding XQ. Detection of Normal Aging Effects on Human Brain Metabolite Concentrations and Microstructure with Whole-Brain MR Spectroscopic Imaging and Quantitative MR Imaging. AJNR Am J Neuroradiol 2015; 37:447-54. [PMID: 26564440 DOI: 10.3174/ajnr.a4557] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 07/26/2015] [Indexed: 01/02/2023]
Abstract
BACKGROUND AND PURPOSE Knowledge of age-related physiological changes in the human brain is a prerequisite to identify neurodegenerative diseases. Therefore, in this study whole-brain (1)H-MRS was used in combination with quantitative MR imaging to study the effects of normal aging on healthy human brain metabolites and microstructure. MATERIALS AND METHODS Sixty healthy volunteers, 21-70 years of age, were studied. Brain maps of the metabolites NAA, creatine and phosphocreatine, and Cho and the tissue irreversible and reversible transverse relaxation times T2 and T2' were derived from the datasets. The relative metabolite concentrations and the values of relaxation times were measured with ROIs placed within the frontal and parietal WM, centrum semiovale, splenium of the corpus callosum, hand motor area, occipital GM, putamen, thalamus, pons ventral/dorsal, and cerebellar white matter and posterior lobe. Linear regression analysis and Pearson correlation tests were used to analyze the data. RESULTS Aging resulted in decreased NAA concentrations in the occipital GM, putamen, splenium of the corpus callosum, and pons ventral and decreased creatine and phosphocreatine concentrations in the pons dorsal and putamen. Cho concentrations did not change significantly in selected brain regions. T2 increased in the cerebellar white matter and decreased in the splenium of the corpus callosum with aging, while the T2' decreased in the occipital GM, hand motor area, and putamen, and increased in the splenium of the corpus callosum. Correlations were found between NAA concentrations and T2' in the occipital GM and putamen and between creatine and phosphocreatine concentrations and T2' in the putamen. CONCLUSIONS The effects of normal aging on brain metabolites and microstructure are region-dependent. Correlations between both processes are evident in the gray matter. The obtained data could be used as references for future studies on patients.
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Affiliation(s)
- V V Eylers
- From the Institute of Diagnostic and Interventional Neuroradiology (V.V.E., P.B., P.R.D., H.L., X.-Q.D.), Hannover Medical School, Hannover, Germany
| | - A A Maudsley
- Department of Radiology (A.A.M.), University of Miami School of Medicine, Miami, Florida
| | - P Bronzlik
- From the Institute of Diagnostic and Interventional Neuroradiology (V.V.E., P.B., P.R.D., H.L., X.-Q.D.), Hannover Medical School, Hannover, Germany
| | - P R Dellani
- From the Institute of Diagnostic and Interventional Neuroradiology (V.V.E., P.B., P.R.D., H.L., X.-Q.D.), Hannover Medical School, Hannover, Germany
| | - H Lanfermann
- From the Institute of Diagnostic and Interventional Neuroradiology (V.V.E., P.B., P.R.D., H.L., X.-Q.D.), Hannover Medical School, Hannover, Germany
| | - X-Q Ding
- From the Institute of Diagnostic and Interventional Neuroradiology (V.V.E., P.B., P.R.D., H.L., X.-Q.D.), Hannover Medical School, Hannover, Germany
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Mapping of cerebral metabolic rate of oxygen using dynamic susceptibility contrast and blood oxygen level dependent MR imaging in acute ischemic stroke. Neuroradiology 2015; 57:1253-61. [DOI: 10.1007/s00234-015-1592-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/04/2015] [Indexed: 11/27/2022]
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Quantitative T2, T2*, and T2' MR imaging in patients with ischemic leukoaraiosis might detect microstructural changes and cortical hypoxia. Neuroradiology 2015; 57:1023-30. [PMID: 26227168 DOI: 10.1007/s00234-015-1565-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/13/2015] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Quantitative MRI with T2, T2*, and T2' mapping has been shown to non-invasively depict microstructural changes (T2) and oxygenation status (T2* and T2') that are invisible on conventional MRI. Therefore, we aimed to assess whether T2 and T2' quantification detects cerebral (micro-)structural damage and chronic hypoxia in lesions and in normal appearing white matter (WM) and gray matter (GM) of patients with ischemic leukoaraiosis (IL). Measurements were complemented by the assessment of the cerebral blood flow (CBF) and the degree of GM and WM atrophy. METHODS Eighteen patients with IL and 18 age-matched healthy controls were included. High-resolution, motion-corrected T2, T2*, and T2' mapping, CBF mapping (pulsed arterial spin labeling, PASL), and segmentation of GM and WM were used to depict specific changes in both groups. All parameters were compared between patients and healthy controls, using t testing. Values of p < 0.05 were accepted as statistically significant. RESULTS Patients showed significantly increased T2 in lesions (p < 0.01) and in unaffected WM (p = 0.045) as well as significantly increased T2* in lesions (p = 0.003). A significant decrease of T2' was detected in patients in unaffected WM (p = 0.027), while no T2' changes were observed in GM (p = 0.13). Both unaffected WM and GM were significantly decreased in volume in the patient-group (p < 0.01). No differences of PASL-based CBF could be shown. CONCLUSION Non-invasive quantitative MRI with T2, T2*, and T2' mapping might be used to detect subtle structural and metabolic changes in IL. Assessing the grade of microstructural damage and hypoxia might be helpful to monitor disease progression and to perform risk assessment.
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Bauer S, Wagner M, Seiler A, Hattingen E, Deichmann R, Nöth U, Singer OC. Quantitative T2'-mapping in acute ischemic stroke. Stroke 2014; 45:3280-6. [PMID: 25278559 DOI: 10.1161/strokeaha.114.006530] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND PURPOSE Quantitative T2'-mapping detects regional changes in the relation of oxygenated and deoxygenated haemoglobine and might reflect areas with increased oxygen extraction. T2'-mapping in conjunction with an elaborate algorithm for motion correction was performed in patients with acute large-vessel stroke, and quantitative T2'-values were determined within the diffusion-weighted imaging lesion and perfusion-restricted tissue. METHODS Eleven patients (median age, 71 years) with acute middle cerebral or internal carotid artery occlusion underwent MRI before scheduled endovascular treatment. MR-examination included diffusion- and perfusion-weighted imaging and quantitative, motion-corrected mapping of T2'. Time-to-peak maps were thresholded for different degrees of perfusion delays (eg, ≥0 s, ≥ 2s) when compared with a reference time-to-peak value from healthy contralateral tissue. Mean T2'-values in areas with reduced apparent diffusion coefficient and in areas with impaired perfusion were compared with T2'-values in corresponding contralateral areas. RESULTS Median time between symptom onset and MRI was 238 minutes. T2'-values were significantly reduced within the apparent diffusion coefficient -lesion when compared with contralateral healthy tissue (83 ms [67, 97] versus 97 ms [91, 111]; P<0.003). In perfusion-restricted tissue, T2'-values were also significantly lower when compared with contralateral healthy tissue (ie, for time to peak, ≥0 s 93 ms [86, 102] versus 104 [90, 110]; P=0.008) but were significantly higher than within the apparent diffusion coefficient lesion. The severity of the perfusion impairment had no influence on median T2'-values. CONCLUSIONS Motion-corrected T2'-mapping reveals significant and gradually declining values from healthy to perfusion-disturbed to apparent diffusion coefficient-restricted tissue. Current T2'-mapping can differentiate between the ischemic core and the perfusion-impaired areas but not on its own between penumbral and oligemic tissue.
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Affiliation(s)
- Sonja Bauer
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Marlies Wagner
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Alexander Seiler
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Elke Hattingen
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Ralf Deichmann
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Ulrike Nöth
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Oliver C Singer
- From the Department of Neurology (S.B., A.S., O.C.S.), Institute for Neuroradiology (M.W., E.H.); and Brain Imaging Center (R.D., U.N.), University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
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What can we learn from T2* maps of the cortex? Neuroimage 2013; 93 Pt 2:189-200. [PMID: 23357070 DOI: 10.1016/j.neuroimage.2013.01.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/13/2013] [Accepted: 01/15/2013] [Indexed: 12/13/2022] Open
Abstract
Studies have shown that T2* contrast can reveal features of cortical anatomy. However, understanding the relationship between T2* contrast and the underlying cyto- and myelo-architecture is not an easy task, given the number of confounds, such as myelin, iron, blood vessels and structure orientation. Moreover, it is difficult to obtain reliable T2* measurements in the cortex due to its thin and folded geometry and the presence of artifacts. This review addresses issues associated with T2* mapping in the human cortex. After describing the theory behind T2* relaxation, a list of practical steps is proposed to reliably acquire and process T2* data and then map these values within the cortex using surface-based analysis. The last section addresses the question: "What can we gain from T2* cortical mapping?", with particular emphasis on Brodmann mapping.
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