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Li H, Zu T, Hsu YC, Zhao Z, Liu R, Zheng T, Li Q, Sun Y, Liu D, Zhang J, Zhang Y, Wu D. Inversion-Recovery-Prepared Oscillating Gradient Sequence Improves Diffusion-Time Dependency Measurements in the Human Brain. J Magn Reson Imaging 2023; 57:446-453. [PMID: 35723048 DOI: 10.1002/jmri.28311] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 06/06/2022] [Accepted: 06/06/2022] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Oscillating gradient diffusion MRI (dMRI) enables measurements at a short diffusion-time (td ), but it is challenging for clinical systems. Particularly, the low b-value and low resolution may give rise to cerebrospinal fluid (CSF) contamination. PURPOSE To assess the effect of CSF partial volume on td -dMRI measurements and efficacy of inversion-recovery (IR) prepared oscillating and pulsed gradient dMRI sequence to improve td -dMRI measurements in the human brain. STUDY TYPE Prospective. SUBJECTS Ten normal volunteers and six glioma patients. FIELD STRENGTH/SEQUENCE A 3 T; three-dimensional (3D) IR-prepared oscillating gradient-prepared gradient spin-echo (GRASE) and two-dimensional (2D) IR-prepared oscillating gradient echo-planar imaging (EPI) sequences. ASSESSMENT We assessed the td -dependent patterns of apparent diffusion coefficient (ADC) in several gray and white matter structures, including the hippocampal subfields (head, body, and tail), cortical gray matter, thalamus, and posterior white matter in normal volunteers. Pulsed gradient (0 Hz) and oscillating gradients at frequencies of 20 Hz, 40 Hz, and 60 Hz dMRI were acquired with GRASE and EPI sequences with or without the IR module. We also tested the td -dependency patterns in glioma patients using the EPI sequence with or without the IR module. STATISTICAL TESTS The differences in ADC across the different td s were compared by one-way ANOVA followed by post hoc pairwise t-tests with Bonferroni correction. RESULTS In the healthy subjects, brain regions that were possibly contaminated by CSF signals, such as the hippocampus (head, body, and tail) and cortical gray matter, td -dependent ADC changes were only significant with the IR-prepared 2D and 3D sequences but not with the non-IR sequences. In brain glioblastomas patients, significantly higher td -dependence was observed in the tumor region with the IR module than that without IR (slope = 0.0196 μm2 /msec2 vs. 0.0034 μm2 /msec2 ). CONCLUSION The IR-prepared sequence effectively suppressed the CSF partial volume effect and significantly improved the td -dependent measurements in the human brain. EVIDENCE LEVEL 1 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Haotian Li
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Tao Zu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yi-Cheng Hsu
- MR Collaboration, Siemens Healthcare China, Shanghai, China
| | - Zhiyong Zhao
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ruibin Liu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Tianshu Zheng
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qing Li
- MR Collaboration, Siemens Healthcare China, Shanghai, China
| | - Yi Sun
- MR Collaboration, Siemens Healthcare China, Shanghai, China
| | - Daihong Liu
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Jiuquan Zhang
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Yi Zhang
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Dan Wu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
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Kimura T, Yamashita K, Fukatsu K. Diffusion MR Imaging with T2-based Water Suppression (T2wsup-dMRI). Magn Reson Med Sci 2021; 21:499-515. [PMID: 34305080 PMCID: PMC9316139 DOI: 10.2463/mrms.mp.2021-0007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Purpose: This study proposes and assesses a new diffusion MRI (dMRI) technique to solve problems related to the quantification of parameter maps (apparent diffusion coefficient [ADC] or mean diffusivity [MD], fractional anisotropy [FA]) and misdrawing of fiber tractography (FT) due to cerebrospinal fluid (CSF)-partial volume effects (PVEs) for brain tissues by combining with the T2-based water suppression (T2wsup) technique. Methods: T2wsup–diffusion-weighted imaging (DWI) images were obtained by subtracting those images from the acquired multi-b value (b) DWI images after correcting the signal intensities of multiecho time (TE) images using long TE water signal-dominant images. Quantitative parameter maps and FT were obtained from minimum data points and were compared with those using the standard (without wsup) DWI method, and partly compared with those obtained using other alternative DWI methods of applying fluid attenuation inversion recovery (FLAIR), non-b-zero (NBZ) by theoretical or noise-added simulation and MR images. Results: In the T2wsup-dMRI method, the hyperintense artifacts due to CSF-PVEs in MRI data were dramatically suppressed even at lower b (≲ 500 s/mm2) while keeping the tissue SNR. The quantitative parameter map values became precisely close to the pure tissue values precisely even in water (CSF) PVE voxels in healthy brain tissues (T2 ≲ 100 ms). Furthermore, the fiber tracts were correctly connected, particularly at the fornix in closest contact to the CSF. Conclusion: Solving the problem of CSF-PVE in the current dMRI technique using our proposed T2wsup-dMRI technique is easy, with higher SNR than those obtained with FLAIR or NBZ methods when applying to healthy brain tissues. The proposed T2wsup–dMRI could be useful in clinical settings, although further optimization of the pulse sequence and processing techniques and clinical assessments are required, particularly for long T2 lesions.
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Affiliation(s)
- Tokunori Kimura
- Department of Radiological Science, Shizuoka College of Medical Care Science
| | - Kousuke Yamashita
- Department of Radiological Science, Shizuoka College of Medical Care Science
| | - Kouta Fukatsu
- Department of Radiological Science, Shizuoka College of Medical Care Science
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Bergamino M, Keeling EG, Mishra VR, Stokes AM, Walsh RR. Assessing White Matter Pathology in Early-Stage Parkinson Disease Using Diffusion MRI: A Systematic Review. Front Neurol 2020; 11:314. [PMID: 32477235 PMCID: PMC7240075 DOI: 10.3389/fneur.2020.00314] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/31/2020] [Indexed: 12/15/2022] Open
Abstract
Structural brain white matter (WM) changes such as axonal caliber, density, myelination, and orientation, along with WM-dependent structural connectivity, may be impacted early in Parkinson disease (PD). Diffusion magnetic resonance imaging (dMRI) has been used extensively to understand such pathological WM changes, and the focus of this systematic review is to understand both the methods utilized and their corresponding results in the context of early-stage PD. Diffusion tensor imaging (DTI) is the most commonly utilized method to probe WM pathological changes. Previous studies have suggested that DTI metrics are sensitive in capturing early disease-associated WM changes in preclinical symptomatic regions such as olfactory regions and the substantia nigra, which is considered to be a hallmark of PD pathology and progression. Postprocessing analytic approaches include region of interest-based analysis, voxel-based analysis, skeletonized approaches, and connectome analysis, each with unique advantages and challenges. While DTI has been used extensively to study WM disorganization in early-stage PD, it has several limitations, including an inability to resolve multiple fiber orientations within each voxel and sensitivity to partial volume effects. Given the subtle changes associated with early-stage PD, these limitations result in inaccuracies that severely impact the reliability of DTI-based metrics as potential biomarkers. To overcome these limitations, advanced dMRI acquisition and analysis methods have been employed, including diffusion kurtosis imaging and q-space diffeomorphic reconstruction. The combination of improved acquisition and analysis in DTI may yield novel and accurate information related to WM-associated changes in early-stage PD. In the current article, we present a systematic and critical review of dMRI studies in early-stage PD, with a focus on recent advances in DTI methodology. Yielding novel metrics, these advanced methods have been shown to detect diffuse WM changes in early-stage PD. These findings support the notion of early axonal damage in PD and suggest that WM pathology may go unrecognized until symptoms appear. Finally, the advantages and disadvantages of different dMRI techniques, analysis methods, and software employed are discussed in the context of PD-related pathology.
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Affiliation(s)
- Maurizio Bergamino
- Division of Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States
| | - Elizabeth G. Keeling
- Division of Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Virendra R. Mishra
- Imaging Research, Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, United States
| | - Ashley M. Stokes
- Division of Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States
| | - Ryan R. Walsh
- Muhammad Ali Parkinson Center, Barrow Neurological Institute, Phoenix, AZ, United States
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Filatova OG, van Vliet LJ, Schouten AC, Kwakkel G, van der Helm FCT, Vos FM. Comparison of Multi-Tensor Diffusion Models' Performance for White Matter Integrity Estimation in Chronic Stroke. Front Neurosci 2018; 12:247. [PMID: 29740269 PMCID: PMC5925961 DOI: 10.3389/fnins.2018.00247] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 03/29/2018] [Indexed: 01/23/2023] Open
Abstract
Better insight into white matter (WM) alterations after stroke onset could help to understand the underlying recovery mechanisms and improve future interventions. MR diffusion imaging enables to assess such changes. Our goal was to investigate the relation of WM diffusion characteristics derived from diffusion models of increasing complexity with the motor function of the upper limb. Moreover, we aimed to evaluate the variation of such characteristics across different WM structures of chronic stroke patients in comparison to healthy subjects. Subjects were scanned with a two b-value diffusion-weighted MRI protocol to exploit multiple diffusion models: single tensor, single tensor with isotropic compartment, bi-tensor model, bi-tensor with isotropic compartment. From each model we derived the mean tract fractional anisotropy (FA), mean (MD), radial (RD) and axial (AD) diffusivities outside the lesion site based on a WM tracts atlas. Asymmetry of these measures was correlated with the Fugl-Meyer upper extremity assessment (FMA) score and compared between patient and control groups. Eighteen chronic stroke patients and eight age-matched healthy individuals participated in the study. Significant correlation of the outcome measures with the clinical scores of stroke recovery was found. The lowest correlation of the corticospinal tract FAasymmetry and FMA was with the single tensor model (r = -0.3, p = 0.2) whereas the other models reported results in the range of r = -0.79 ÷ -0.81 and p = 4E-5 ÷ 8E-5. The corticospinal tract and superior longitudinal fasciculus showed most alterations in our patient group relative to controls. Multiple compartment models yielded superior correlation of the diffusion measures and FMA compared to the single tensor model.
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Affiliation(s)
- Olena G. Filatova
- Department of Biomechanical Engineering, Delft University of Technology, Delft, Netherlands
- Quantitative Imaging Group, Department of Imaging Physics, Delft University of Technology, Delft, Netherlands
| | - Lucas J. van Vliet
- Quantitative Imaging Group, Department of Imaging Physics, Delft University of Technology, Delft, Netherlands
| | - Alfred C. Schouten
- Department of Biomechanical Engineering, Delft University of Technology, Delft, Netherlands
- Laboratory for Biomechanical Engineering, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands
| | - Gert Kwakkel
- Department of Rehabilitation Medicine, MOVE Research Institute Amsterdam, Amsterdam Neurosciences, VU University Medical Center, Amsterdam, Netherlands
| | | | - Frans M. Vos
- Quantitative Imaging Group, Department of Imaging Physics, Delft University of Technology, Delft, Netherlands
- Department of Radiology, Academic Medical Center, Amsterdam, Netherlands
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5
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Wong SM, Backes WH, Zhang CE, Staals J, van Oostenbrugge RJ, Jeukens CRLPN, Jansen JFA. On the Reproducibility of Inversion Recovery Intravoxel Incoherent Motion Imaging in Cerebrovascular Disease. AJNR Am J Neuroradiol 2018; 39:226-231. [PMID: 29217741 DOI: 10.3174/ajnr.a5474] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 10/03/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Intravoxel incoherent motion imaging can measure both microvascular and parenchymal abnormalities simultaneously. The contamination of CSF signal can be suppressed using inversion recovery preparation. The clinical feasibility of inversion recovery-intravoxel incoherent motion imaging was investigated in patients with cerebrovascular disease by studying its reproducibility. MATERIALS AND METHODS Sixteen patients with cerebrovascular disease (66 ± 8 years of age) underwent inversion recovery-intravoxel incoherent motion imaging twice. The reproducibility of the perfusion volume fraction and parenchymal diffusivity was calculated with the coefficient of variation, intraclass correlation coefficient, and the repeatability coefficient. ROIs included the normal-appearing white matter, cortex, deep gray matter, white matter hyperintensities, and vascular lesions. RESULTS Values for the perfusion volume fraction ranged from 2.42 to 3.97 ×10-2 and for parenchymal diffusivity from 7.20 to 9.11 × 10-4 mm2/s, with higher values found in the white matter hyperintensities and vascular lesions. Coefficients of variation were <3.70% in normal-appearing tissue and <9.15% for lesions. Intraclass correlation coefficients were good to excellent, showing values ranging from 0.82 to 0.99 in all ROIs, except the deep gray matter and cortex, with intraclass correlation coefficients of 0.66 and 0.54, respectively. The repeatability coefficients ranged from 0.15 to 0.96 × 10-2 and 0.10 to 0.37 × 10-4 mm2/s for perfusion volume fraction and parenchymal diffusivity, respectively. CONCLUSIONS Good reproducibility of inversion recovery-intravoxel incoherent motion imaging was observed with low coefficients of variation and high intraclass correlation coefficients in normal-appearing tissue and lesion areas in cerebrovascular disease. Good reproducibility of inversion recovery-intravoxel incoherent motion imaging in cerebrovascular disease is feasible in monitoring disease progression or treatment responses in the clinic.
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Affiliation(s)
- S M Wong
- From the Departments of Radiology and Nuclear Medicine (S.M.W., W.H.B., C.R.L.P.N.J., J.F.A.J.)
- School for Mental Health and Neuroscience (S.M.W., W.H.B., C.E.Z., R.J.v.O., J.F.A.J.)
| | - W H Backes
- From the Departments of Radiology and Nuclear Medicine (S.M.W., W.H.B., C.R.L.P.N.J., J.F.A.J.)
- School for Mental Health and Neuroscience (S.M.W., W.H.B., C.E.Z., R.J.v.O., J.F.A.J.)
| | - C E Zhang
- Neurology (C.E.Z., J.S., R.J.v.O.)
- School for Mental Health and Neuroscience (S.M.W., W.H.B., C.E.Z., R.J.v.O., J.F.A.J.)
- Cardiovascular Research Institute Maastricht (C.E.Z., J.S., R.J.v.O.), Maastricht University Medical Centre, Maastricht, the Netherlands
| | - J Staals
- Neurology (C.E.Z., J.S., R.J.v.O.)
- Cardiovascular Research Institute Maastricht (C.E.Z., J.S., R.J.v.O.), Maastricht University Medical Centre, Maastricht, the Netherlands
| | - R J van Oostenbrugge
- Neurology (C.E.Z., J.S., R.J.v.O.)
- School for Mental Health and Neuroscience (S.M.W., W.H.B., C.E.Z., R.J.v.O., J.F.A.J.)
- Cardiovascular Research Institute Maastricht (C.E.Z., J.S., R.J.v.O.), Maastricht University Medical Centre, Maastricht, the Netherlands
| | - C R L P N Jeukens
- From the Departments of Radiology and Nuclear Medicine (S.M.W., W.H.B., C.R.L.P.N.J., J.F.A.J.)
| | - J F A Jansen
- From the Departments of Radiology and Nuclear Medicine (S.M.W., W.H.B., C.R.L.P.N.J., J.F.A.J.)
- School for Mental Health and Neuroscience (S.M.W., W.H.B., C.E.Z., R.J.v.O., J.F.A.J.)
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Tipirneni-Sajja A, Christensen S, Straka M, Inoue M, Lansberg MG, Mlynash M, Bammer R, Parsons MW, Donnan GA, Davis SM, Albers GW. Prediction of final infarct volume on subacute MRI by quantifying cerebral edema in ischemic stroke. J Cereb Blood Flow Metab 2017; 37:3077-3084. [PMID: 28155584 PMCID: PMC5536812 DOI: 10.1177/0271678x16683960] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Final infarct volume in stroke trials is assessed on images obtained between 30 and 90 days after stroke onset. Imaging at such delayed timepoints is problematic because patients may be lost to follow-up or die before the scan. Obtaining an early assessment of infarct volume on subacute scans avoids these limitations; however, it overestimates true infarct volume because of edema. The aim of this study was to develop a novel approach to quantify edema so that final infarct volumes can be approximated on subacute scans. We analyzed data from 20 stroke patients (median age, 75 years) who had baseline, subacute (fu5d) and late (fu90d) MRI scans. Edema displaces CSF from sulci and ventricles; therefore, edema volume was estimated as change in CSF volume between baseline and spatially coregistered fu5d ADC maps. The median (interquartile range, IQR) estimated edema volume was 13.3 (7.5-37.7) mL. The fu5d lesion volumes correlated well with fu90d infarct volumes with slope: 1.24. With edema correction, fu5d infarct volumes are in close agreement, slope: 0.97 and strongly correlated with actual fu90d volumes. The median (IQR) difference between actual and predicted infarct volumes was 0.1 (-3.0-5.7) mL. In summary, this novel technique for estimation of edema allows final infarct volume to be predicted from subacute MRI.
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Affiliation(s)
- Aaryani Tipirneni-Sajja
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA.,2 Department of Biomedical Engineering, University of Memphis, Memphis, TN, USA.,3 Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Soren Christensen
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA
| | - Matus Straka
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA
| | - Manabu Inoue
- 4 Department of Neurology, Showa University Fujigaoka Hospital, Yokohama, Japan
| | - Maarten G Lansberg
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA
| | - Michael Mlynash
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA
| | - Roland Bammer
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA
| | - Mark W Parsons
- 5 Department of Neurology, John Hunter Hospital, University of Newcastle, Newcastle, NSW, Australia
| | - Geoffrey A Donnan
- 6 Florey Neuroscience Institutes, Austin Health, University of Melbourne, Melbourne, VIC, Australia
| | - Stephen M Davis
- 7 Royal Melbourne Hospital, University of Melbourne, Melbourne, VIC, Australia
| | - Gregory W Albers
- 1 Stanford Stroke Center, Stanford University Medical Center, Stanford, CA, USA
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Samson RS, Lévy S, Schneider T, Smith AK, Smith SA, Cohen-Adad J, Gandini Wheeler-Kingshott CAM. ZOOM or Non-ZOOM? Assessing Spinal Cord Diffusion Tensor Imaging Protocols for Multi-Centre Studies. PLoS One 2016; 11:e0155557. [PMID: 27171194 PMCID: PMC4865165 DOI: 10.1371/journal.pone.0155557] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/29/2016] [Indexed: 12/02/2022] Open
Abstract
The purpose of this study was to develop and evaluate two spinal cord (SC) diffusion tensor imaging (DTI) protocols, implemented at multiple sites (using scanners from two different manufacturers), one available on any clinical scanner, and one using more advanced options currently available in the research setting, and to use an automated processing method for unbiased quantification. DTI parameters are sensitive to changes in the diseased SC. However, imaging the cord can be technically challenging due to various factors including its small size, patient-related and physiological motion, and field inhomogeneities. Rapid acquisition sequences such as Echo Planar Imaging (EPI) are desirable but may suffer from image distortions. We present a multi-centre comparison of two acquisition protocols implemented on scanners from two different vendors (Siemens and Philips), one using a reduced field-of-view (rFOV) EPI sequence, and one only using options available on standard clinical scanners such as outer volume suppression (OVS). Automatic analysis was performed with the Spinal Cord Toolbox for unbiased and reproducible quantification of DTI metrics in the white matter. Images acquired using the rFOV sequence appear less distorted than those acquired using OVS alone. SC DTI parameter values obtained using both sequences at all sites were consistent with previous measurements made at 3T. For the same scanner manufacturer, DTI parameter inter-site SDs were smaller for the rFOV sequence compared to the OVS sequence. The higher inter-site reproducibility (for the same manufacturer and acquisition details, i.e. ZOOM data acquired at the two Philips sites) of rFOV compared to the OVS sequence supports the idea that making research options such as rFOV more widely available would improve accuracy of measurements obtained in multi-centre clinical trials. Future multi-centre studies should also aim to match the rFOV technique and signal-to-noise ratios in all sequences from different manufacturers/sites in order to avoid any bias in measured DTI parameters and ensure similar sensitivity to pathological changes.
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Affiliation(s)
- Rebecca S. Samson
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom
- * E-mail:
| | - Simon Lévy
- Institute of Biomedical Engineering, Ecole Polytechnique de Montreal, Montreal, QC, Canada
- Functional Neuroimaging Unit, University of Montreal, Montreal, QC, Canada
| | - Torben Schneider
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom
- Philips Healthcare, Guilford, Surrey, United Kingdom
| | - Alex K. Smith
- Vanderbilt University Institute of Imaging Science (VUIIS), Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Seth A. Smith
- Vanderbilt University Institute of Imaging Science (VUIIS), Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Julien Cohen-Adad
- Institute of Biomedical Engineering, Ecole Polytechnique de Montreal, Montreal, QC, Canada
- Functional Neuroimaging Unit, University of Montreal, Montreal, QC, Canada
| | - Claudia A. M. Gandini Wheeler-Kingshott
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom
- Brain MRI 3T Center, C. Mondino National Neurological Institute, Pavia, Italy
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
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8
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Salminen LE, Conturo TE, Bolzenius JD, Cabeen RP, Akbudak E, Paul RH. REDUCING CSF PARTIAL VOLUME EFFECTS TO ENHANCE DIFFUSION TENSOR IMAGING METRICS OF BRAIN MICROSTRUCTURE. TECHNOLOGY AND INNOVATION 2016; 18:5-20. [PMID: 27721931 DOI: 10.21300/18.1.2016.5] [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] [Indexed: 01/08/2023]
Abstract
Technological advances over recent decades now allow for in vivo observation of human brain tissue through the use of neuroimaging methods. While this field originated with techniques capable of capturing macrostructural details of brain anatomy, modern methods such as diffusion tensor imaging (DTI) that are now regularly implemented in research protocols have the ability to characterize brain microstructure. DTI has been used to reveal subtle micro-anatomical abnormalities in the prodromal phase ofº various diseases and also to delineate "normal" age-related changes in brain tissue across the lifespan. Nevertheless, imaging artifact in DTI remains a significant limitation for identifying true neural signatures of disease and brain-behavior relationships. Cerebrospinal fluid (CSF) contamination of brain voxels is a main source of error on DTI scans that causes partial volume effects and reduces the accuracy of tissue characterization. Several methods have been proposed to correct for CSF artifact though many of these methods introduce new limitations that may preclude certain applications. The purpose of this review is to discuss the complexity of signal acquisition as it relates to CSF artifact on DTI scans and review methods of CSF suppression in DTI. We will then discuss a technique that has been recently shown to effectively suppress the CSF signal in DTI data, resulting in fewer errors and improved measurement of brain tissue. This approach and related techniques have the potential to significantly improve our understanding of "normal" brain aging and neuropsychiatric and neurodegenerative diseases. Considerations for next-level applications are discussed.
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Affiliation(s)
- Lauren E Salminen
- Department of Psychology, University of Missouri - Saint Louis, St. Louis, MO, USA
| | - Thomas E Conturo
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Ryan P Cabeen
- Computer Science Department, Brown University, Providence, RI, USA
| | - Erbil Akbudak
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Robert H Paul
- Missouri Institute of Mental Health, St. Louis, MO, USA
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Kwon OH, Park H, Seo SW, Na DL, Lee JM. A framework to analyze cerebral mean diffusivity using surface guided diffusion mapping in diffusion tensor imaging. Front Neurosci 2015; 9:236. [PMID: 26236180 PMCID: PMC4500906 DOI: 10.3389/fnins.2015.00236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 06/21/2015] [Indexed: 11/21/2022] Open
Abstract
The mean diffusivity (MD) value has been used to describe microstructural properties in Diffusion Tensor Imaging (DTI) in cortical gray matter (GM). Recently, researchers have applied a cortical surface generated from the T1-weighted volume. When the DTI data are analyzed using the cortical surface, it is important to assign an accurate MD value from the volume space to the vertex of the cortical surface, considering the anatomical correspondence between the DTI and the T1-weighted image. Previous studies usually sampled the MD value using the nearest-neighbor (NN) method or Linear method, even though there are geometric distortions in diffusion-weighted volumes. Here we introduce a Surface Guided Diffusion Mapping (SGDM) method to compensate for such geometric distortions. We compared our SGDM method with results using NN and Linear methods by investigating differences in the sampled MD value. We also projected the tissue classification results of non-diffusion-weighted volumes to the cortical midsurface. The CSF probability values provided by the SGDM method were lower than those produced by the NN and Linear methods. The MD values provided by the NN and Linear methods were significantly greater than those of the SGDM method in regions suffering from geometric distortion. These results indicate that the NN and Linear methods assigned the MD value in the CSF region to the cortical midsurface (GM region). Our results suggest that the SGDM method is an effective way to correct such mapping errors.
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Affiliation(s)
- Oh-Hun Kwon
- Department of Biomedical Engineering, Hanyang University Seoul, South Korea
| | - Hyunjin Park
- School of Electronic and Electrical Engineering, Sungkyunkwan University Suwon, South Korea
| | - Sang-Won Seo
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul, South Korea
| | - Duk L Na
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul, South Korea
| | - Jong-Min Lee
- Department of Biomedical Engineering, Hanyang University Seoul, South Korea
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Jung KJ. Removal of partial volume averaging with free water in MR diffusion tensor imaging using inversion recovery for b0 image. Magn Reson Imaging 2014; 32:619-24. [PMID: 24666572 DOI: 10.1016/j.mri.2014.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 02/17/2014] [Accepted: 02/17/2014] [Indexed: 11/16/2022]
Abstract
PURPOSE To remove the partial volume averaging effect of free water in MR diffusion imaging of neural tissues by use of the fluid attenuated inversion recovery (FLAIR) without the penalty of an extended scan time. MATERIALS AND METHODS The magnetic resonance images were obtained from a normal volunteer in a coronal slice orientation at 3T with the 20-channel rf coil. In diffusion imaging only the b0 images were obtained with the FLAIR contrast while the diffusion weighted images were obtained without the FLAIR contrast. A composition of FLAIR b0 and non-FLAIR diffusion weighted images was used in calculating the diffusion tensor and fractional anisotropy after compensating the reduced signal amplitude due to the inversion recovery in the FLAIR b0 images. The fractional anisotropy of the non-FLAIR, FLAIR, and the composite methods were analyzed for the mean and histogram in the corpus callosum, cervical spine, and the fornix tracts. RESULTS The partial volume averaging effect was observed in the corpus callosum, the cervical spine, and the fornix tracts in the non-FLAIR b0 and diffusion images. The partial volume averaging effect was removed in the FLAIR diffusion images which took more than twice the scan time than the non-FLAIR diffusion imaging. The proposed composite FLAIR diffusion imaging removed the partial volume averaging effect as in the FLAIR diffusion imaging. The distribution of the FA histogram was very different between the non-FLAIR and FLAIR diffusion images, while it was very similar between the FLAIR and the composite FLAIR after correcting the white matter signal in the FLAIR b0 images. CONCLUSIONS The proposed composite FLAIR diffusion imaging method was equally effective in removing the partial volume averaging effect as the FLAIR diffusion imaging at a limited increase of the scan time since only a small number of b0 images needed to be obtained with the FLAIR contrast.
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Affiliation(s)
- Kwan-Jin Jung
- Research MRI Facility, Department of Radiology, University of Louisville, KY, USA.
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11
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Hasan KM, Moeller FG, Narayana PA. DTI-based segmentation and quantification of human brain lateral ventricular CSF volumetry and mean diffusivity: validation, age, gender effects and biophysical implications. Magn Reson Imaging 2014; 32:405-12. [PMID: 24582546 DOI: 10.1016/j.mri.2014.01.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/18/2014] [Accepted: 01/19/2014] [Indexed: 12/21/2022]
Abstract
The human brain lateral ventricular (LV) cerebrospinal fluid (CSF) volume has been used as a neuroimaging marker of brain changes in health and disease. The LV CSF diffusivity may offer a useful quality assurance measure and become a potential noninvasive marker of deep brain temperature. In this work we sought to validate a method for human brain lateral ventricular (LV) cerebrospinal fluid (CSF) using diffusion tensor imaging (DTI) contrast to provide LV volume and corresponding DTI metrics. We compared LV volume obtained using DTI with that obtained using validated segmentations of the LV on T1-weighted data. DTI and T1-weighted data were acquired at 3T on 49 healthy males and 56 age-matched females aged 18-59 years. We showed histogram distributions of LV DTI metrics to establish quality assurance measures. We also analyzed the age and gender effects of LV volume and diffusivity. LV volumes estimated using both T1-weighted and DTI correlated strongly in males and females (ICC=0.99; median Dice index ~80%). The LV-to-intracranial volume percentage increased significantly with age only in males, using the DTI-based approach (r=0.39; p=0.005). LV CSF Mean diffusivity was greater in males than females ((~1.2%; p=0.03). Mean diffusivity of lateral ventricular CSF decreased significantly with age in healthy adults (r=-0.30; p=0.02). Our results highlight the importance of age and gender-based analyses and the potential of LV diffusivity measures as a quantitative marker.
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Affiliation(s)
- Khader M Hasan
- Department of Diagnostic and Interventional Imaging, The University of Texas Health Science Center, Houston, TX, USA.
| | - F Gerard Moeller
- Medical School, Department Interventional Imaging, The University of Texas Health Science Center, Houston, TX, USA
| | - Ponnada A Narayana
- Department of Diagnostic and Interventional Imaging, The University of Texas Health Science Center, Houston, TX, USA
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12
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Li S, Wang B, Xu P, Lin Q, Gong G, Peng X, Fan Y, He Y, Huang R. Increased global and local efficiency of human brain anatomical networks detected with FLAIR-DTI compared to non-FLAIR-DTI. PLoS One 2013; 8:e71229. [PMID: 23967170 PMCID: PMC3742791 DOI: 10.1371/journal.pone.0071229] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 06/30/2013] [Indexed: 11/30/2022] Open
Abstract
Diffusion-weighted MRI (DW-MRI), the only non-invasive technique for probing human brain white matter structures in vivo, has been widely used in both fundamental studies and clinical applications. Many studies have utilized diffusion tensor imaging (DTI) and tractography approaches to explore the topological properties of human brain anatomical networks by using the single tensor model, the basic model to quantify DTI indices and tractography. However, the conventional DTI technique does not take into account contamination by the cerebrospinal fluid (CSF), which has been known to affect the estimated DTI measures and tractography in the single tensor model. Previous studies have shown that the Fluid-Attenuated Inversion Recovery (FLAIR) technique can suppress the contribution of the CSF to the DW-MRI signal. We acquired DTI datasets from twenty-two subjects using both FLAIR-DTI and conventional DTI (non-FLAIR-DTI) techniques, constructed brain anatomical networks using deterministic tractography, and compared the topological properties of the anatomical networks derived from the two types of DTI techniques. Although the brain anatomical networks derived from both types of DTI datasets showed small-world properties, we found that the brain anatomical networks derived from the FLAIR-DTI showed significantly increased global and local network efficiency compared with those derived from the conventional DTI. The increases in the network regional topological properties derived from the FLAIR-DTI technique were observed in CSF-filled regions, including the postcentral gyrus, periventricular regions, inferior frontal and temporal gyri, and regions in the visual cortex. Because brain anatomical networks derived from conventional DTI datasets with tractography have been widely used in many studies, our findings may have important implications for studying human brain anatomical networks derived from DW-MRI data and tractography.
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Affiliation(s)
- Shumei Li
- Center for the Study of Applied Psychology, Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, School of Psychology, South China Normal University, Guangzhou, P. R. China
| | - Bin Wang
- Center for the Study of Applied Psychology, Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, School of Psychology, South China Normal University, Guangzhou, P. R. China
| | - Pengfei Xu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, P. R. China
| | - Qixiang Lin
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, P. R. China
| | - Gaolang Gong
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, P. R. China
| | - Xiaoling Peng
- Center for the Study of Applied Psychology, Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, School of Psychology, South China Normal University, Guangzhou, P. R. China
| | - Yuanyuan Fan
- Center for the Study of Applied Psychology, Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, School of Psychology, South China Normal University, Guangzhou, P. R. China
| | - Yong He
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, P. R. China
| | - Ruiwang Huang
- Center for the Study of Applied Psychology, Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, School of Psychology, South China Normal University, Guangzhou, P. R. China
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13
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Scherrer B, Warfield SK. Parametric representation of multiple white matter fascicles from cube and sphere diffusion MRI. PLoS One 2012; 7:e48232. [PMID: 23189128 PMCID: PMC3506641 DOI: 10.1371/journal.pone.0048232] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 09/28/2012] [Indexed: 12/13/2022] Open
Abstract
The characterization of the complex diffusion signal arising from the brain remains an open problem. Many representations focus on characterizing the global shape of the diffusion profile at each voxel and are limited to the assessment of connectivity. In contrast, Multiple Fascicle Models (MFM) seek to represent the contribution from each white matter fascicle and may be useful in the investigation of both white matter connectivity and diffusion properties of each individual fascicle. However, the most appropriate representation of multiple fascicles remains unclear. In particular, a multiple tensor representation of multiple fascicles has frequently been reported to be numerically challenging and unstable. We provide here the first analytical demonstration that when using a diffusion MRI acquisition with only one non-zero b-value, such as in conventional single-shell HARDI acquisition, a co-linearity in model parameters makes the precise model estimation impossible. Motivated by this theoretical result, we propose the novel CUSP (CUbe and SPhere) optimal acquisition scheme to achieve multiple non-zero b-values. It combines the gradients of a single-shell HARDI with gradients in its enclosing cube, in which varying b-values can be acquired by modulation of the gradient strength, without modifying the minimum echo time. Compared to a multi-shell HARDI acquisition, our scheme has significantly increased signal-to-noise ratio. We propose a novel estimation algorithm that enables efficient, robust and accurate estimation of the parameters of a multi-tensor model. In conjunction with a CUSP acquisition, it enables full estimation of the multi-tensor model. We present an evaluation of CUSP-MFM on both synthetic phantoms and invivo data. We report qualitative and quantitative experimental evaluations which demonstrate the ability of CUSP-MFM to characterize multiple fascicles from short duration acquisitions. CUSP-MFM enables rapid and effective investigation of multiple white matter fascicles, in both normal development and in disease and injury, in research and clinical practice.
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Affiliation(s)
- Benoit Scherrer
- Computational Radiology Laboratory, Department of Radiology Children's Hospital, Boston, Massachusetts, United States of America.
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14
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Yang AW, Jensen JH, Hu CC, Tabesh A, Falangola MF, Helpern JA. Effect of cerebral spinal fluid suppression for diffusional kurtosis imaging. J Magn Reson Imaging 2012; 37:365-71. [PMID: 23034866 DOI: 10.1002/jmri.23840] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 08/27/2012] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To evaluate the cerebral spinal fluid (CSF) partial volume effect on diffusional kurtosis imaging (DKI) metrics in white matter and cortical gray matter. MATERIALS AND METHODS Four healthy volunteers participated in this study. Standard DKI and fluid-attenuated inversion recovery (FLAIR) DKI experiments were performed using a twice-refocused-spin-echo diffusion sequence. The conventional diffusion tensor imaging (DTI) metrics of fractional anisotropy (FA), mean, axial, and radial diffusivity (MD, D[symbol in text], D[symbol in text] together with DKI metrics of mean, axial, and radial kurtosis (MK, K[symbol in text], K[symbol in text], were measured and compared. Single image slices located above the lateral ventricles, with similar anatomical features for each subject, were selected to minimize the effect of CSF from the ventricles. RESULTS In white matter, differences of less than 10% were observed between diffusion metrics measured with standard DKI and FLAIR-DKI sequences, suggesting minimal CSF contamination. For gray matter, conventional DTI metrics differed by 19% to 52%, reflecting significant CSF partial volume effects. Kurtosis metrics, however, changed by 11% or less, indicating greater robustness with respect to CSF contamination. CONCLUSION Kurtosis metrics are less sensitive to CSF partial voluming in cortical gray matter than conventional diffusion metrics. The kurtosis metrics may then be more specific indicators of changes in tissue microstructure, provided the effect sizes for the changes are comparable.
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Affiliation(s)
- Alicia W Yang
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016, USA.
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15
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Affiliation(s)
- Michael D Hill
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.
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16
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Cheng YW, Chung HW, Chen CY, Chou MC. Diffusion tensor imaging with cerebrospinal fluid suppression and signal-to-noise preservation using acquisition combining fluid-attenuated inversion recovery and conventional imaging: Comparison of fiber tracking. Eur J Radiol 2011; 79:113-7. [DOI: 10.1016/j.ejrad.2009.12.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 12/30/2009] [Indexed: 11/30/2022]
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17
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Warach S, Baird AE, Dani KA, Wintermark M, Kidwell CS. Magnetic Resonance Imaging of Cerebrovascular Diseases. Stroke 2011. [DOI: 10.1016/b978-1-4160-5478-8.10046-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Regional diffusion changes of cerebral grey matter during normal aging—A fluid-inversion prepared diffusion imaging study. Eur J Radiol 2010; 75:134-8. [DOI: 10.1016/j.ejrad.2009.04.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 04/13/2009] [Accepted: 04/14/2009] [Indexed: 11/18/2022]
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19
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Influence of fluid-attenuated inversion-recovery on stroke apparent diffusion coefficient measurements and its clinical application. Eur J Radiol 2010; 75:e76-81. [PMID: 20047810 DOI: 10.1016/j.ejrad.2009.11.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 11/29/2009] [Accepted: 11/30/2009] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND PURPOSE The application of a fluid-attenuated inversion-recovery pulse with a conventional diffusion-weighted MRI sequence (FLAIR DWI) decreases the partial volume effects from cerebrospinal fluid on apparent diffusion coefficient (ADC) measurements. For this reason, FLAIR DWI may be more useful in the evaluation of ischemic stroke, but few studies have looked at the effect of FLAIR on ADC measurements in this setting. This study quantitatively compares FLAIR DWI and conventional DWI in ischemic stroke of varying ages to assess the potential advantages of this technique. METHODS We respectively analyzed 139 DWI studies in patients with ischemic stroke with and without FLAIR at varying time points ranging from hyperacute to chronic. ADC values were measured in each lesion, as well as in the contralateral normal side. Comparisons were made between the ADC values obtained from the DWI sequences with and without FLAIR for both the lesion and the normal contralateral side. RESULTS The ADC measurements within the ischemic lesion were very similar on FLAIR DWI and conventional DWI for lesions less than 14 days old (p>0.05), but were significantly decreased on FLAIR DWI for lesions between 15 and 30 days old and in lesions >31 days old (chronic stage) (p<0.01). The contralateral ADC values were all significantly decreased on the FLAIR DWI sequence compared with conventional DWI (p<0.01). CONCLUSIONS The application of an inversion pulse does not significantly affect the ADC values for early stage ischemic stroke (less than 14 days from symptom onset), but results in a more accurate relative ADC measurement by reducing the cerebrospinal fluid partial volume effects of the normal contralateral side. In addition, combined with the conventional DWI, FLAIR DWI may be helpful in determining the age of ischemic lesions.
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20
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Ding AY, Hui ES, Wu EX. The effects of hypercapnia on DTI quantification in anesthetized rat brain. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2009:2711-4. [PMID: 19964038 DOI: 10.1109/iembs.2009.5333392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Diffusion Tensor Imaging (DTI) offers a valuable in vivo tool to characterize water diffusion behavior in biological tissues, particularly brain tissues. The accuracy of DTI derived parameters can directly affect the interpretation of underlying microstructures, physiology or pathologies. It is anticipated that measurement of apparent diffusion coefficient (ADC) using DTI could be influenced and complicated by the presence of water molecules in brain vasculature. However, little is known about to what degree does blood signal from vasculature affect the diffusion quantitation. In this study, we examined the effects of hypercapnia on DTI quantification in rat brains using inhalation of 5% carbon dioxide (CO2). It was found that statistically significant changes occurred in parametric DTI maps in response to cerebrovascular challenges, indicating that vascular factors could interfere with in vivo DTI characterization of neural tissues. Consequently, hemodynamic alterations can potentially affect the DTI quantitation and detection of tissue microstructures and pathological alterations. Therefore, cautions must be taken when interpreting DTI parameters in vivo.
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Affiliation(s)
- Abby Y Ding
- Laboratory of Biomedical Imaging and Signal Processing and the Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong
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21
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Abstract
Diffusion and perfusion MR imaging have proven to be highly useful in the clinical description and understanding of acute and hyperacute ischemic stroke. In this article, the authors give a brief overview of the basic concepts of diffusion and perfusion imaging and describe some of the current developments, applications, challenges, and limitations of these techniques as applied to cerebral ischemia.
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22
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Henning EC, Latour LL, Warach S. Verification of enhancement of the CSF space, not parenchyma, in acute stroke patients with early blood-brain barrier disruption. J Cereb Blood Flow Metab 2008; 28:882-6. [PMID: 18091756 PMCID: PMC5257002 DOI: 10.1038/sj.jcbfm.9600598] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Enhancement on post-contrast fluid-attenuated inversion recovery (FLAIR) images after acute stroke has been attributed to early blood-brain barrier disruption. Using an estimate of parenchymal volume fraction and the apparent diffusion coefficient (ADC), we investigated the relative contributions of cerebral spinal fluid (CSF) and parenchyma to enhancement seen on postcontrast FLAIR. Enhancing regions were found to have low parenchymal volume fractions and high ADC values, approaching that of pure CSF. These findings suggest that contrast enhancement on FLAIR occurs predominately in the CSF space, not parenchyma.
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Affiliation(s)
- Erica C Henning
- Section on Stroke Diagnostics and Therapeutics, Stroke Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
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23
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Tofts PS, Jackson JS, Tozer DJ, Cercignani M, Keir G, MacManus DG, Ridgway GR, Ridha BH, Schmierer K, Siddique D, Thornton JS, Wroe SJ, Fox NC. Imaging cadavers: cold FLAIR and noninvasive brain thermometry using CSF diffusion. Magn Reson Med 2008; 59:190-5. [PMID: 18058937 DOI: 10.1002/mrm.21456] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
There is increasing interest in imaging cadavers for noninvasive autopsies for research purposes. However, the temperature is well below that of in vivo imaging, and a variety of interesting 'cold brain' effects are observed. At lower temperatures conventional FLAIR sequences no longer produce dark cerebrospinal fluid (CSF); T(1) is reduced from about 4.0 sec in vivo to 1.7 sec at 1 degrees C. The diffusion coefficient (DC) of CSF is much reduced (from 3.1 10(-9) m(2)s(-1) in vivo to 1.1 at 1 degrees C). DC values therefore provide a noninvasive thermometer to measure brain core temperature to within 1.0 degrees C. In three cadavers DC values were 1.1-1.5 10(-9) m(2)s(-1), indicating brain core temperatures of 1-10 degrees C, consistent with external thermocouple measurements. An improved inversion time (TI(0)) can then be found for FLAIR. At 10 degrees C this Cold FLAIR sequence (TI(0) = 1.5 sec) gave black CSF. Expressions for CSF DC and T(1) as a function of temperature were produced. A measurement of CSF DC could be converted directly to temperature and the required TI(0) found. In vitro values of CSF DC were about 1% lower than that of water. Thus, FLAIR imaging can be optimized for cadaveric brains at low and unknown temperatures, thereby improving value for autopsy purposes and facilitating comparisons with in vivo imaging.
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Affiliation(s)
- Paul S Tofts
- Institute of Neurology, Queen Square, University College London, UK.
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24
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Ewell LA, Watchman CJ, Wharton K. Sulci density map to aid in use of apparent diffusion coefficient for therapy evaluation. Magn Reson Imaging 2008; 26:20-5. [PMID: 17560748 DOI: 10.1016/j.mri.2007.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 02/16/2007] [Accepted: 04/10/2007] [Indexed: 10/23/2022]
Abstract
In order to more accurately asses variations in the apparent diffusion coefficient used for therapy evaluation, we have studied the variation in sulci density in the human brain. Sagittal, axial and coronal magnetic resonance imaging scans have been analyzed to determine the change of the coefficient of variance of pixel intensity as a function of position. In the sagittal direction, relative to the 50% most medial slices, we find an 11.0%+/-4.8% (S.D.) decrease in the next 25% (12.5% on each side) of the slices. The most lateral 25% of the slices had less of a decrease and more variation: 7.0%+/-12.2%. Similar variations were observed in axial and coronal scans.
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Affiliation(s)
- Lars A Ewell
- Department of Radiation Oncology, University of Arizona, Tucson, AZ 85724-5175, USA.
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25
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Nikolova S, Sun Z, Bellyou M, Bartha R. Comparison of T2 and LASER T2dagger image contrast in a rat model of acute cerebral ischemia. Magn Reson Imaging 2007; 26:323-9. [PMID: 18060718 DOI: 10.1016/j.mri.2007.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 06/01/2007] [Accepted: 07/24/2007] [Indexed: 10/22/2022]
Abstract
Previous studies have shown that T2(dagger)-weighted magnetic resonance images acquired using localization by adiabatic selective refocusing (LASER) can provide early tissue contrast following ischemia, possibly due to alterations in microscopic susceptibility within the tissue. The purpose of this study was to make a direct in vivo comparison of T2-, T2(dagger)- and diffusion-weighted image contrast during acute ischemia. Acute middle cerebral artery (MCA) occlusion was attempted in 14 rats using a modified Tamura approach incorporating electrocoagulation of the left MCA. T2(dagger)-weighted LASER images (Echo Time [TE]=108 ms), T2-weighted Carr-Purcell-Meiboom-Gill (CPMG) images (TE=110 ms) and diffusion-weighted images (b value=105 s/mm(2)) were acquired at 4 T within 1.5 h of ischemia onset. Tissue contrast in the MCA territory was quantified for histologically verified ischemic tissue (n=6) and in sham controls (n=4). T2(dagger)-weighted LASER images demonstrated greater contrast compared to the T2-weighted CPMG images, and more focal contrast compared to the diffusion-weighted images, suggesting different contrast mechanisms were involved.
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Affiliation(s)
- Simona Nikolova
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.
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26
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Lee JD, Chang TC, Huang CH, Wu SJ, Chen CJ. Computer-aided diagnosis system for acute stroke using diffusion weighted images with volume calculation. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:1529-32. [PMID: 17271988 DOI: 10.1109/iembs.2004.1403468] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The diffusion weighted image (DWI) technique is routinely used for diagnosis and treatment of early stroke due to its superior performance, especially when it is compared with conventional magnetic resonance image (MRI) for detection of acute ischemic stroke. Using DWI examination, This work has proposed a computer-aided diagnosis system, which can effectively calculate the volume size of a lesion and provide clinical doctor the 3D reconstruction data of the lesion. The potential benefits of using our system include the higher accuracy of acute stroke lesion definition, the reduced time and procedure of calculating the volume of a lesion, and providing 3D reconstruction image of stroke patients, which can effectively assist doctors in making more accurate diagnoses and treating patients in a more convenient way. Compared with the traditional method, the experimental results have shown the superior performance of this proposed system.
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Affiliation(s)
- J D Lee
- Dept. of Electr. Eng, Chang Gung Univ., Tao-Yuan, Taiwan
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27
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Rau PR, Sellner J, Heiland S, Plaschke K, Schellinger PD, Meyding-Lamadé UK, Lamadé WR. Apparent diffusion coefficient in the aging mouse brain: A magnetic resonance imaging study. Life Sci 2006; 78:1175-80. [PMID: 16213530 DOI: 10.1016/j.lfs.2005.06.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Accepted: 06/22/2005] [Indexed: 11/28/2022]
Abstract
Novel magnetic resonance imaging sequences have and still continue to play an increasing role in neuroimaging and neuroscience. Among these techniques, diffusion-weighted imaging (DWI) has revolutionized the diagnosis and management of diseases such as stroke, neoplastic disease and inflammation. However, the effects of aging on diffusion are yet to be determined. To establish reference values for future experimental mouse studies we tested the hypothesis that absolute apparent diffusion coefficients (ADC) of the normal brain change with age. A total of 41 healthy mice were examined by T2-weighted imaging and DWI. For each animal ADC frequency histograms (i) of the whole brain were calculated on a voxel-by-voxel basis and region-of-interest (ROI) measurements (ii) performed and related to the animals' age. The mean entire brain ADC of mice <3 months was 0.715(+/-0.016) x 10(-3) mm2/s, no significant difference to mice aged 4 to 5 months (0.736(+/-0.040) x 10(-3) mm2/s) or animals older than 9 months 0.736(+/-0.020) x 10(-3) mm2/s. Mean whole brain ADCs showed a trend towards lower values with aging but both methods (i + ii) did not reveal a significant correlation with age. ROI measurements in predefined areas: 0.723(+/-0.057) x 10(-3) mm2/s in the parietal lobe, 0.659(+/-0.037) x 10(-3) mm2/s in the striatum and 0.679(+/-0.056) x 10(-3) mm2/s in the temporal lobe. With advancing age, we observed minimal diffusion changes in the whole mouse brain as well as in three ROIs by determination of ADCs. According to our data ADCs remain nearly constant during the aging process of the brain with a small but statistically non-significant trend towards a decreased diffusion in older animals.
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Affiliation(s)
- Philipp R Rau
- University of Heidelberg, Department of Neurology, INF 400-Kopfklinik, D-69120 Heidelberg, Germany.
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Liu T, Young G, Huang L, Chen NK, Wong STC. 76-space analysis of grey matter diffusivity: methods and applications. Neuroimage 2006; 31:51-65. [PMID: 16434215 DOI: 10.1016/j.neuroimage.2005.11.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Revised: 11/14/2005] [Accepted: 11/21/2005] [Indexed: 10/25/2022] Open
Abstract
Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) allow in vivo investigation of molecular motion of tissue water at a microscopic level in cerebral gray matter (GM) and white matter (WM). DWI/DTI measure of water diffusion has been proven to be invaluable for the study of many neurodegenerative diseases (e.g., Alzheimer's disease and Creutzfeldt-Jakob disease) that predominantly involve GM. Thus, quantitative analysis of GM diffusivity is of scientific interest and is promised to have a clinical impact on the investigation of normal brain aging and neuropathology. In this paper, we propose an automated framework for analysis of GM diffusivity in 76 standard anatomic subdivisions of gray matter to facilitate studies of neurodegenerative and other gray matter neurological diseases. The computational framework includes three enabling technologies: (1) automatic parcellation of structural MRI GM into 76 precisely defined neuroanatomic subregions ("76-space"), (2) automated segmentation of GM, WM and CSF based on DTI data, and (3) automatic measurement of the average apparent diffusion coefficient (ADC) in each segmented GM subregion. We evaluate and validate this computational framework for 76-space GM diffusivity analysis using data from normal volunteers and from patients with Creutzfeldt-Jakob disease.
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Affiliation(s)
- Tianming Liu
- Center for Bioinformatics, Harvard Center for Neurodegeneration and Repair, Harvard Medical School, MA 02478, USA.
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Chen PE, Simon JE, Hill MD, Sohn CH, Dickhoff P, Morrish WF, Sevick RJ, Frayne R. Acute Ischemic Stroke: Accuracy of Diffusion-weighted MR Imaging—Effects ofbValue and Cerebrospinal Fluid Suppression. Radiology 2006; 238:232-9. [PMID: 16373771 DOI: 10.1148/radiol.2381041113] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
PURPOSE To prospectively determine which diffusion-weighted magnetic resonance (MR) imaging technique (ie, conventional diffusion-weighted MR imaging [b = 1000 or 1500 sec/mm2] or fluid-inversion prepared diffusion [FLIPD] MR imaging [b = 1500 sec/mm2]) is most accurate in depicting acute ischemic stroke at 3 T. MATERIALS AND METHODS The Health Research Ethics Board approved this study; written informed consent was provided by all participants or their surrogate. Diffusion-weighted MR imaging was performed in 75 consecutive patients (43 men, 32 women; mean age, 64.0 years) with acute ischemic stroke. Two experienced neuroradiologists determined the presence of hyperacute stroke lesions at diffusion-weighted MR imaging by locating areas of hyperintensity that corresponded to regions with a decreased diffusion coefficient. These findings were used as the reference standard. Four raters who were blinded to patient history assessed all images and apparent diffusion coefficient maps for the presence of changes that were consistent with acute ischemic stroke. Accuracy, sensitivity, specificity, negative predictive value, positive predictive value, and inter- and intrarater reliability scores were calculated for each technique. RESULTS Specificity, positive predictive value, and accuracy were not significantly different among the techniques. FLIPD MR images obtained with a b value of 1500 sec/mm2 had decreased sensitivity for acute ischemic stroke (mean, 61.8%; 95% confidence interval [CI]: 55.4%, 67.9%) compared with conventional diffusion-weighted MR images obtained with a b value of either 1000 sec/mm2 (mean, 82.5%; 95% CI: 77.1%, 87.0%) or 1500 sec/mm2 (mean, 84.5%; 95% CI: 79.3%, 88.9%). FLIPD MR images also had decreased negative predictive value (mean, 96.5%; 95% CI: 95.7%, 97.2%) compared with conventional diffusion-weighted MR images obtained with a b value of either 1000 sec/mm2 (mean, 98.4%; 95% CI: 97.8%, 98.8%) or 1500 sec/mm2 (mean, 98.6%; 95% CI: 98.1%, 99.0%). Intra- and interrater reliability scores were generally excellent for all three techniques. CONCLUSION FLIPD MR images obtained with a b value of 1500 sec/mm2 are less suitable for the detection of acute ischemic stroke owing to a decreased sensitivity and negative predictive value. The performance of the two conventional diffusion-weighted MR imaging techniques (b = 1000 and 1500 sec/mm2) was equivalent.
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Affiliation(s)
- Philip E Chen
- Seaman Family MR Research Centre, Foothills Medical Centre, Calgary Health Region, Calgary, AB, T2N 2T9, Canada
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Miller JC, Sorensen AG. Imaging biomarkers predictive of disease/therapy outcome: ischemic stroke and drug development. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2005; 62:319-56. [PMID: 16329261 DOI: 10.1007/3-7643-7426-8_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Janet C Miller
- MGH-HST Center for Biomarkers in Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
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Guadagno JV, Warburton EA, Aigbirhio FI, Smielewski P, Fryer TD, Harding S, Price CJ, Gillard JH, Carpenter TA, Baron JC. Does the acute diffusion-weighted imaging lesion represent penumbra as well as core? A combined quantitative PET/MRI voxel-based study. J Cereb Blood Flow Metab 2004; 24:1249-54. [PMID: 15545920 DOI: 10.1097/01.wcb.0000141557.32867.6b] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In acute ischemic stroke, the diffusion-weighted imaging (DWI) lesion is widely held to represent the core of irreversible damage and is therefore crucial in selecting patients for thrombolysis. However, recent research suggests it may also represent penumbra. An illustrative patient was imaged 7 hours after stroke onset with back-to-back 3T diffusion tensor imaging and quantitative positron emission tomography, which showed a DWI lesion and misery perfusion, respectively. Using previously validated voxel-based probabilistic CBF, CMRO2, and Oxygen Extraction Fraction (OEF) thresholds, the authors show that the DWI lesion contained not only core but also substantial proportions of penumbra. Also, severe apparent diffusion coefficient reductions were present within the potentially salvageable penumbra as well as in the core. These findings have potential implications regarding treatment decisions.
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Affiliation(s)
- Joseph V Guadagno
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 2QQ, UK
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Heiss WD, Sobesky J, Smekal UV, Kracht LW, Lehnhardt FG, Thiel A, Jacobs AH, Lackner K. Probability of cortical infarction predicted by flumazenil binding and diffusion-weighted imaging signal intensity: a comparative positron emission tomography/magnetic resonance imaging study in early ischemic stroke. Stroke 2004; 35:1892-8. [PMID: 15218157 DOI: 10.1161/01.str.0000134746.93535.9b] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The differentiation of reversible from irreversible ischemic damage is essential for identifying patients with acute ischemic deficits who may benefit from therapeutic interventions. Diffusion-weighted imaging (DWI) has become the method of choice to detect ischemic lesions. Positron emission tomography (PET) of the central benzodiazepine receptor ligand 11C flumazenil (FMZ) has been shown to be a reliable marker of neuronal integrity. These 2 imaging parameters were compared with respect to the probability to predict cortical infarction in early ischemic stroke. METHODS In 12 patients with acute stroke, results from DWI (median, 6.5 hours after symptom onset) and FMZ-PET (interval, 85 minutes between DWI and PET) were compared with infarct extension 24 to 48 hours after onset of stroke on T2-weighted magnetic resonance imaging (T2-MRI). Probability curves predictive of eventual infarction were computed using respective DWI, FMZ, and apparent diffusion coefficient (ADC) values for voxels of interest (VOI) later classified as representing infarcted or noninfarcted tissue. RESULTS Ninety-five percent limits predictive of cortical infarction were determined for relative FMZ binding (< or =3.2), DWI signal intensity (> or =1.18), and ADC values (< or =0.83). Cortical regions with values beyond these 95% limits did not necessarily overlap with nor were fully congruous with final cortical infarct volumes. The respective median volumes for these regions were FMZ median 10.9, range 0 to 99.7 cm3; DWI median 15.2, range 0 to 116.0 cm3; ADC median 12.4, range 0 to 112.7 cm3; and final infarct median 14.9, range 0 to 114.7 cm(3). Overall, 83.5% of the final infarct, on average, was predicted by decreased FMZ binding, 84.7% by increased DWI signal intensity, and 70.9% by a decreased ADC value. The portions of the final infarct not predicted in the early investigation (false-negatives) were 4.8 cm3 (median) for FMZ, 3.7 cm3 for DWI, and 6.0 cm3 for ADC. The false-positive volumes not included in the final infarct were 0 cm3 (median) for FMZ, 5.1 cm3 for DWI, and 3.6 cm3 for ADC. CONCLUSIONS These results indicate that FMZ-PET and DWI are comparable in the prediction of probability of ischemic cortical infarction, but FMZ-PET carries a lower probability of false-positive prediction. The final infarcts include tissue not identified by these imaging modalities; at the time of the study, these tissue compartments are viable and could benefit from treatment. The discrepancy in predictive probability could be related to the fundamental difference of the measured variables: benzodiazepine receptor activity is a reliable marker of neuronal integrity in the cortex, and movement of water molecules in the extracellular space might be a more variable indicator of tissue damage.
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Affiliation(s)
- Wolf-Dieter Heiss
- Max Planck Institute for Neurological Research, University of Cologne, Cologne, Germany.
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Ma X, Kadah YM, LaConte SM, Hu X. Enhancing measured diffusion anisotropy in gray matter by eliminating CSF contamination with FLAIR. Magn Reson Med 2004; 51:423-7. [PMID: 14755672 DOI: 10.1002/mrm.10703] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In this work, the effect of fluid-attenuated inversion recovery (FLAIR) on measured diffusion anisotropy was investigated in gray matter. DTI data were obtained with and without FLAIR in six normal volunteers. The application of FLAIR was experimentally demonstrated to lead to a consistent increase in fractional anisotropy (FA) in gray-matter regions, which was attributed to suppressed partial volume effects from CSF. In addition to these experimental results, Monte Carlo simulations were performed to ascertain the effect of noise on the measured FA under the experimental conditions of this study. The experimentally observed effect of noise was corroborated by the simulation, indicating that the increase in the measured FA was not due to a noise-related bias but to an actual increase in diffusion anisotropy. This enhanced measurement of diffusion anisotropy can be potentially used to differentiate directionally dependent structure and tracking fibers in gray matter.
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Affiliation(s)
- Xiangyang Ma
- Biomedical Imaging Technology Center, Wallace Coulter Department of Biomedical Engineering, Emory University/Georgia Institute of Technology, Atlanta, Georgia 30322, USA
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Bykowski JL, Latour LL, Warach S. More Accurate Identification of Reversible Ischemic Injury in Human Stroke by Cerebrospinal Fluid Suppressed Diffusion-Weighted Imaging. Stroke 2004; 35:1100-6. [PMID: 15060314 DOI: 10.1161/01.str.0000125867.86298.6a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The apparent diffusion coefficient (ADC) derived from diffusion-weighted (DWI) MRI has been used to differentiate reversible from irreversible ischemic injury. However, the ADC can be falsely elevated by partial volume averaging of cerebrospinal fluid (CSF) with parenchyma, limiting the accuracy of this approach. This study tested the hypothesis that the accuracy of differentiating reversible from irreversible ischemic injury could be improved by CSF suppression at image acquisition. METHODS Sixteen patients presenting within 6 hours from symptoms, and having partial reversal of the acute lesion on DWI were studied using conventional CSF-suppressed DWI. Lesions were segmented from coregistered acute DWI and follow-up fluid-attenuated inversion recovery (FLAIR) series. The segmented volumes were applied to conventional (ADC(C)) and CSF-suppressed ADC (ADC(FLIPD)) maps to classify each voxel as progressed to infarct or reversed. Individual voxel ADC values were pooled across all patients. Sensitivity to predict reversal, specificity, and accuracy were calculated for both methods. RESULTS A total of 25 313 voxels were classified as progressed and 31 952 voxels reversed. Across all lesion voxels, ADC(FLIPD) values more accurately depicted tissue fate compared with ADC(C) values (P<0.0001). The largest difference in the two methods was in voxels with <75% parenchyma, where the accuracy of ADC(C) was only 50% compared with 62% for ADC(FLIPD.) CONCLUSIONS CSF-suppressed ADC measurements gave a more accurate identification of reversible ischemic injury in this sample. We predict that multimodal MRI models of tissue viability in ischemic stroke will be more accurate if CSF-suppressed ADC measurements are used.
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Affiliation(s)
- Julie L Bykowski
- Section on Stroke Diagnostics and Therapeutics, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Md, USA
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Bhagat YA, Beaulieu C. Diffusion anisotropy in subcortical white matter and cortical gray matter: Changes with aging and the role of CSF-suppression. J Magn Reson Imaging 2004; 20:216-27. [PMID: 15269946 DOI: 10.1002/jmri.20102] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To determine the relevance of cerebrospinal fluid (CSF)-suppression for the measurement of diffusion anisotropy in well-localized areas of the brain, particularly the subcortical white matter (WM) within the gyri and cortical gray matter (GM), in young and elderly subjects, and to assess the changes of water diffusivity in the brain with normal aging. MATERIALS AND METHODS Quantitative measures of anisotropy in 26 regions, including subcortical WM (i.e., in the gyri), cortical GM, major deep WM, and deep GM regions of young (21-25 years, N = 8) and elderly (61-74 years, N = 10) normal volunteers, were assessed with CSF-suppressed diffusion tensor imaging (DTI) relative to standard DTI. RESULTS CSF-suppressed DTI demonstrated significant increases in fractional anisotropy (FA) of 3-12% in the young and 2-14% in the elderly groups with the largest changes being in the subcortical WM of the gyri. Furthermore, FA decreased by 10-19% in the subcortical WM of the gyri of the elderly subjects relative to the young, primarily due to increases in the perpendicular diffusivity, lambda(3), with age. CONCLUSION CSF-suppressed DTI yields more accurate measures of quantitative anisotropy in cortical and subcortical brain regions. Reductions of anisotropy with aging were predominantly observed in subcortical WM of the gyri.
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Affiliation(s)
- Yusuf A Bhagat
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta T6G 2V2, Canada
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Warach S, Kidwell CS, Baird AE. Magnetic Resonance Imaging. Stroke 2004. [DOI: 10.1016/b0-44-306600-0/50024-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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Kidwell CS, Alger JR, Saver JL. Beyond mismatch: evolving paradigms in imaging the ischemic penumbra with multimodal magnetic resonance imaging. Stroke 2003; 34:2729-35. [PMID: 14576370 DOI: 10.1161/01.str.0000097608.38779.cc] [Citation(s) in RCA: 333] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The ability to quickly and efficiently identify the ischemic penumbra in the acute stroke clinical setting is an important goal for stroke researchers and clinicians. Early and accurate identification of potentially salvageable versus irreversibly infarcted brain tissue may enable selection of the most appropriate candidates for early stroke therapies and identify patients who may still benefit from late recanalization or neuroprotective treatment. Recent advances in magnetic resonance imaging of the ischemic penumbra have been driven by serial MRI studies characterizing the natural evolution of cerebral infarction as well as the brain's response to reperfusion. SUMMARY OF COMMENT Based on these studies, various models for imaging the penumbra with MRI have been proposed, including the pioneering diffusion-perfusion mismatch model and later multivariate approaches. Each model has its own unique advantages and disadvantages. CONCLUSIONS There now are sufficient data to support paradigm shifts in a variety of central tenets regarding MRI and the ischemic penumbra. These include the insights that diffusion-perfusion mismatch does not optimally define the penumbra; that early diffusion lesions are in part reversible and often include both irreversibly infarcted tissue and penumbra; that the visible zone of perfusion abnormality overestimates the penumbra by including regions of benign oligemia; that MRI is a very practical method for acute stroke imaging; and that therapeutic salvage of the ischemic penumbra has been demonstrated in humans using diffusion-perfusion MRI.
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Affiliation(s)
- Chelsea S Kidwell
- University of California at Los Angeles Stroke Center, Los Angeles, CA 90095, USA.
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Current awareness in NMR in biomedicine. NMR IN BIOMEDICINE 2003; 16:56-65. [PMID: 12619641 DOI: 10.1002/nbm.799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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Affiliation(s)
- Steven Warach
- Stroke Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Md 20892-4129, USA.
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