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Trotier AJ, Corbin N, Miraux S, Ribot EJ. Accelerated 3D multi-echo spin-echo sequence with a subspace constrained reconstruction for whole mouse brain T 2 mapping. Magn Reson Med 2024; 92:1525-1539. [PMID: 38725149 DOI: 10.1002/mrm.30146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/28/2024] [Accepted: 04/18/2024] [Indexed: 07/23/2024]
Abstract
PURPOSE To accelerate whole-brain quantitativeT 2 $$ {\mathrm{T}}_2 $$ mapping in preclinical imaging setting. METHODS A three-dimensional (3D) multi-echo spin echo sequence was highly undersampled with a variable density Poisson distribution to reduce the acquisition time. Advanced iterative reconstruction based on linear subspace constraints was employed to recover high-quality raw images. Different subspaces, generated using exponential or extended-phase graph (EPG) simulations or from low-resolution calibration images, were compared. The subspace dimension was investigated in terms ofT 2 $$ {\mathrm{T}}_2 $$ precision. The method was validated on a phantom containing a wide range ofT 2 $$ {\mathrm{T}}_2 $$ and was then applied to monitor metastasis growth in the mouse brain at 4.7T. Image quality andT 2 $$ {\mathrm{T}}_2 $$ estimation were assessed for 3 acceleration factors (6/8/10). RESULTS The EPG-based dictionary gave robust estimations of a large range ofT 2 $$ {\mathrm{T}}_2 $$ . A subspace dimension of 6 was the best compromise betweenT 2 $$ {\mathrm{T}}_2 $$ precision and image quality. Combining the subspace constrained reconstruction with a highly undersampled dataset enabled the acquisition of whole-brainT 2 $$ {\mathrm{T}}_2 $$ maps, the detection and the monitoring of metastasis growth of less than 500μ m 3 $$ \mu {\mathrm{m}}^3 $$ . CONCLUSION Subspace-based reconstruction is suitable for 3DT 2 $$ {\mathrm{T}}_2 $$ mapping. This method can be used to reach an acceleration factor up to 8, corresponding to an acquisition time of 25 min for an isotropic 3D acquisition of 156μ $$ \mu $$ m on the mouse brain, used here for monitoring metastases growth.
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Affiliation(s)
- Aurélien J Trotier
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, University Bordeaux, Bordeaux, France
| | - Nadège Corbin
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, University Bordeaux, Bordeaux, France
| | - Sylvain Miraux
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, University Bordeaux, Bordeaux, France
| | - Emeline J Ribot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, University Bordeaux, Bordeaux, France
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2
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Radunsky D, Solomon C, Stern N, Blumenfeld-Katzir T, Filo S, Mezer A, Karsa A, Shmueli K, Soustelle L, Duhamel G, Girard OM, Kepler G, Shrot S, Hoffmann C, Ben-Eliezer N. A comprehensive protocol for quantitative magnetic resonance imaging of the brain at 3 Tesla. PLoS One 2024; 19:e0297244. [PMID: 38820354 PMCID: PMC11142522 DOI: 10.1371/journal.pone.0297244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 01/01/2024] [Indexed: 06/02/2024] Open
Abstract
Quantitative MRI (qMRI) has been shown to be clinically useful for numerous applications in the brain and body. The development of rapid, accurate, and reproducible qMRI techniques offers access to new multiparametric data, which can provide a comprehensive view of tissue pathology. This work introduces a multiparametric qMRI protocol along with full postprocessing pipelines, optimized for brain imaging at 3 Tesla and using state-of-the-art qMRI tools. The total scan time is under 50 minutes and includes eight pulse-sequences, which produce range of quantitative maps including T1, T2, and T2* relaxation times, magnetic susceptibility, water and macromolecular tissue fractions, mean diffusivity and fractional anisotropy, magnetization transfer ratio (MTR), and inhomogeneous MTR. Practical tips and limitations of using the protocol are also provided and discussed. Application of the protocol is presented on a cohort of 28 healthy volunteers and 12 brain regions-of-interest (ROIs). Quantitative values agreed with previously reported values. Statistical analysis revealed low variability of qMRI parameters across subjects, which, compared to intra-ROI variability, was x4.1 ± 0.9 times higher on average. Significant and positive linear relationship was found between right and left hemispheres' values for all parameters and ROIs with Pearson correlation coefficients of r>0.89 (P<0.001), and mean slope of 0.95 ± 0.04. Finally, scan-rescan stability demonstrated high reproducibility of the measured parameters across ROIs and volunteers, with close-to-zero mean difference and without correlation between the mean and difference values (across map types, mean P value was 0.48 ± 0.27). The entire quantitative data and postprocessing scripts described in the manuscript are publicly available under dedicated GitHub and Figshare repositories. The quantitative maps produced by the presented protocol can promote longitudinal and multi-center studies, and improve the biological interpretability of qMRI by integrating multiple metrics that can reveal information, which is not apparent when examined using only a single contrast mechanism.
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Affiliation(s)
- Dvir Radunsky
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
| | - Chen Solomon
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
| | - Neta Stern
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
| | | | - Shir Filo
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Aviv Mezer
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Anita Karsa
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Karin Shmueli
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | | | | | | | - Gal Kepler
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- School of Neurobiology, Biochemistry and Biophysics, Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Shai Shrot
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- Department of Diagnostic Imaging, Sheba Medical Center, Ramat-Gan, Israel
| | - Chen Hoffmann
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- Department of Diagnostic Imaging, Sheba Medical Center, Ramat-Gan, Israel
| | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Center for Advanced Imaging Innovation and Research (CAI2R), New-York University Langone Medical Center, New York, NY, United States of America
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Holodov M, Markus I, Solomon C, Shahar S, Blumenfeld-Katzir T, Gepner Y, Ben-Eliezer N. Probing muscle recovery following downhill running using precise mapping of MRI T 2 relaxation times. Magn Reson Med 2023; 90:1990-2000. [PMID: 37345717 DOI: 10.1002/mrm.29765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023]
Abstract
PURPOSE Postexercise recovery rate is a vital component of designing personalized training protocols and rehabilitation plans. Tracking exercise-induced muscle damage and recovery requires sensitive tools that can probe the muscles' state and composition noninvasively. METHODS Twenty-four physically active males completed a running protocol consisting of a 60-min downhill run on a treadmill at -10% incline and 65% of maximal heart rate. Quantitative mapping of MRI T2 was performed using the echo-modulation-curve algorithm before exercise, and at two time points: 1 h and 48 h after exercise. RESULTS T2 values increased by 2%-4% following exercise in the primary mover muscles and exhibited further elevation of 1% after 48 h. For the antagonist muscles, T2 values increased only at the 48-h time point (2%-3%). Statistically significant decrease in the SD of T2 values was found following exercise for all tested muscles after 1 h (16%-21%), indicating a short-term decrease in the heterogeneity of the muscle tissue. CONCLUSION MRI T2 relaxation time constitutes a useful quantitative marker for microstructural muscle damage, enabling region-specific identification for short-term and long-term systemic processes, and sensitive assessment of muscle recovery following exercise-induced muscle damage. The variability in T2 changes across different muscle groups can be attributed to their different role during downhill running, with immediate T2 elevation occurring in primary movers, followed by delayed elevation in both primary and antagonist muscle groups, presumably due to secondary damage caused by systemic processes.
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Affiliation(s)
- Maria Holodov
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Irit Markus
- Department of Epidemiology and Preventive Medicine, School of Public Health and Sylvan Adams Sports Institute, Tel-Aviv University, Tel-Aviv, Israel
| | - Chen Solomon
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Shimon Shahar
- Center of AI and Data Science, Tel Aviv University, Tel Aviv, Israel
| | | | - Yftach Gepner
- Department of Epidemiology and Preventive Medicine, School of Public Health and Sylvan Adams Sports Institute, Tel-Aviv University, Tel-Aviv, Israel
| | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
- Center for Advanced Imaging Innovation and Research, New York University Langone Medical Center, New York, USA
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4
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Solomon C, Shmueli O, Shrot S, Blumenfeld-Katzir T, Radunsky D, Omer N, Stern N, Reichman DBA, Hoffmann C, Salti M, Greenspan H, Ben-Eliezer N. Psychophysical Evaluation of Visual vs. Computer-Aided Detection of Brain Lesions on Magnetic Resonance Images. J Magn Reson Imaging 2023; 58:642-649. [PMID: 36495014 DOI: 10.1002/jmri.28559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 07/20/2023] Open
Abstract
BACKGROUND Magnetic resonance imaging (MRI) diagnosis is usually performed by analyzing contrast-weighted images, where pathology is detected once it reached a certain visual threshold. Computer-aided diagnosis (CAD) has been proposed as a way for achieving higher sensitivity to early pathology. PURPOSE To compare conventional (i.e., visual) MRI assessment of artificially generated multiple sclerosis (MS) lesions in the brain's white matter to CAD based on a deep neural network. STUDY TYPE Prospective. POPULATION A total of 25 neuroradiologists (15 males, age 39 ± 9, 9 ± 9.8 years of experience) independently assessed all synthetic lesions. FIELD STRENGTH/SEQUENCE A 3.0 T, T2 -weighted multi-echo spin-echo (MESE) sequence. ASSESSMENT MS lesions of varying severity levels were artificially generated in healthy volunteer MRI scans by manipulating T2 values. Radiologists and a neural network were tasked with detecting these lesions in a series of 48 MR images. Sixteen images presented healthy anatomy and the rest contained a single lesion at eight increasing severity levels (6%, 9%, 12%, 15%, 18%, 21%, 25%, and 30% elevation in T2 ). True positive (TP) rates, false positive (FP) rates, and odds ratios (ORs) were compared between radiological diagnosis and CAD across the range lesion severity levels. STATISTICAL TESTS Diagnostic performance of the two approaches was compared using z-tests on TP rates, FP rates, and the logarithm of ORs across severity levels. A P-value <0.05 was considered statistically significant. RESULTS ORs of identifying pathology were significantly higher for CAD vis-à-vis visual inspection for all lesions' severity levels. For a 6% change in T2 value (lowest severity), radiologists' TP and FP rates were not significantly different (P = 0.12), while the corresponding CAD results remained statistically significant. DATA CONCLUSION CAD is capable of detecting the presence or absence of more subtle lesions with greater precision than the representative group of 25 radiologists chosen in this study. LEVEL OF EVIDENCE 1 TECHNICAL EFFICACY: Stage 3.
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Affiliation(s)
- Chen Solomon
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Omer Shmueli
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Shai Shrot
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- Department of Diagnostic Imaging, Sheba Medical Center, Ramat-Gan, Israel
| | | | - Dvir Radunsky
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Noam Omer
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Neta Stern
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | | | - Chen Hoffmann
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- Department of Diagnostic Imaging, Sheba Medical Center, Ramat-Gan, Israel
| | - Moti Salti
- Brain Imaging Research Center (BIRC), Ben-Gurion University, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Hayit Greenspan
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Center for Advanced Imaging Innovation and Research (CAI2R), New York University, New York, New York, USA
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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5
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Beracha I, Seginer A, Tal A. Adaptive model-based Magnetic Resonance. Magn Reson Med 2023. [PMID: 37154407 DOI: 10.1002/mrm.29688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 04/11/2023] [Accepted: 04/14/2023] [Indexed: 05/10/2023]
Abstract
PURPOSE Conventional sequences are static in nature, fixing measurement parameters in advance in anticipation of a wide range of expected tissue parameter values. We set out to design and benchmark a new, personalized approach-termed adaptive MR-in which incoming subject data is used to update and fine-tune the pulse sequence parameters in real time. METHODS We implemented an adaptive, real-time multi-echo (MTE) experiment for estimating T2 s. Our approach combined a Bayesian framework with model-based reconstruction. It maintained and continuously updated a prior distribution of the desired tissue parameters, including T2 , which was used to guide the selection of sequence parameters in real time. RESULTS Computer simulations predicted accelerations between 1.7- and 3.3-fold for adaptive multi-echo sequences relative to static ones. These predictions were corroborated in phantom experiments. In healthy volunteers, our adaptive framework accelerated the measurement of T2 for n-acetyl-aspartate by a factor of 2.5. CONCLUSION Adaptive pulse sequences that alter their excitations in real time could provide substantial reductions in acquisition times. Given the generality of our proposed framework, our results motivate further research into other adaptive model-based approaches to MRI and MRS.
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Affiliation(s)
- Inbal Beracha
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Assaf Tal
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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6
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Daniel G, Meirav G, Noam O, Tamar BK, Dvir R, Ricardo O, Noam BE. Fast and accurate T 2 mapping using Bloch simulations and low-rank plus sparse matrix decomposition. Magn Reson Imaging 2023; 98:66-75. [PMID: 36649808 DOI: 10.1016/j.mri.2023.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 01/08/2023] [Indexed: 01/15/2023]
Abstract
PURPOSE MRI's T2 relaxation time is one of the key contrast mechanisms for clinical diagnosis and prognosis of pathologies. Mapping this relaxation time, however, involves extensive scan times, which are needed to collect quantitative data, thereby impeding its integration into clinical routine. This study employs a low-rank plus sparse (L + S) signal decomposition approach in order to reconstruct accurate T2-maps from highly undersampled multi-echo spin-echo (MESE) MRI data. METHODS Two new algorithms are presented: the first uses standard L + S approach, where both L and S are iteratively updated. The second technique, dubbed SPArse and fixed RanK (SPARK), uses a fixed-rank L, under the assumption that most MESE information is found in the L component and that this rank can be pre-calculated. The utility of these new techniques is demonstrated on in vivo brain and calf data at x2 to x6 acceleration factors. RESULTS Accelerated T2 maps showed improved accuracy compared to fully sampled ground truth maps, when using L + S and SPARK techniques vis-à-vis standard GRAPPA acceleration. CONCLUSION SPARK provides accurate T2 maps with increased robustness to the selection of reconstruction parameters making it suitable to a wide range of applications and facilitating the use of quantitative T2 information in clinical settings.
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Affiliation(s)
- Grzeda Daniel
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
| | - Galun Meirav
- Department of Computer Science and Applied Mathematics, Weitzman Institute of Science, Rehovot, Israel
| | - Omer Noam
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
| | | | - Radunsky Dvir
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel
| | - Otazo Ricardo
- Departments of Medical Physics and Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10016, USA
| | - Ben-Eliezer Noam
- Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel; Center for Advanced Imaging Innovation and Research (CAI2R), New-York University Langone Medical Center, New York, NY 10016, USA.
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7
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Nassar J, Trabelsi A, Amer R, Le Fur Y, Attarian S, Radunsky D, Blumenfeld-Katzir T, Greenspan H, Bendahan D, Ben-Eliezer N. Estimation of subvoxel fat infiltration in neurodegenerative muscle disorders using quantitative multi-T 2 analysis. NMR IN BIOMEDICINE 2023:e4947. [PMID: 37021657 DOI: 10.1002/nbm.4947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 02/13/2023] [Accepted: 03/21/2023] [Indexed: 06/19/2023]
Abstract
MRI's T2 relaxation time is a valuable biomarker for neuromuscular disorders and muscle dystrophies. One of the hallmarks of these pathologies is the infiltration of adipose tissue and a loss of muscle volume. This leads to a mixture of two signal components, from fat and from water, to appear in each imaged voxel, each having a specific T2 relaxation time. In this proof-of-concept work, we present a technique that can separate the signals from water and from fat within each voxel, measure their separate T2 values, and calculate their relative fractions. The echo modulation curve (EMC) algorithm is a dictionary-based technique that offers accurate and reproducible mapping of T2 relaxation times. We present an extension of the EMC algorithm for estimating subvoxel fat and water fractions, alongside the T2 and proton-density values of each component. To facilitate data processing, calf and thigh anatomy were automatically segmented using a fully convolutional neural network and FSLeyes software. The preprocessing included creating two signal dictionaries, for water and for fat, using Bloch simulations of the prospective protocol. Postprocessing included voxelwise fitting for two components, by matching the experimental decay curve to a linear combination of the two simulated dictionaries. Subvoxel fat and water fractions and relaxation times were generated and used to calculate a new quantitative biomarker, termed viable muscle index, and reflecting disease severity. This biomarker indicates the fraction of remaining muscle out of the entire muscle region. The results were compared with those using the conventional Dixon technique, showing high agreement (R = 0.98, p < 0.001). It was concluded that the new extension of the EMC algorithm can be used to quantify abnormal fat infiltration as well as identify early inflammatory processes corresponding to elevation in the T2 value of the water (muscle) component. This new ability may improve the diagnostic accuracy of neuromuscular diseases, help stratification of patients according to disease severity, and offer an efficient tool for tracking disease progression.
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Affiliation(s)
- Jannette Nassar
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | | | - Rula Amer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | | | - Shahram Attarian
- Reference Center for Neuromuscular Diseases and ALS, La Timone University Hospital, Aix-Marseille University, Marseille, France
- Inserm, GMGF, Aix Marseille University, Marseille, France
| | - Dvir Radunsky
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | | | - Hayit Greenspan
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | | | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Center for Advanced Imaging Innovation and Research, New York University Langone Medical Center, New York, New York, USA
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Snyder J, Seres P, Stobbe RW, Grenier JG, Smyth P, Blevins G, Wilman AH. Inline dual-echo T2 quantification in brain using a fast mapping reconstruction technique. NMR IN BIOMEDICINE 2023; 36:e4811. [PMID: 35934839 DOI: 10.1002/nbm.4811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 07/06/2022] [Accepted: 07/17/2022] [Indexed: 06/15/2023]
Abstract
T2 mapping from 2D proton density and T2-weighted images (PD-T2) using Bloch equation simulations can be time consuming and introduces a latency between image acquisition and T2 map production. A fast T2 mapping reconstruction method is investigated and compared with a previous modeling approach to reduce computation time and allow inline T2 maps on the MRI console. Brain PD-T2 images from five multiple sclerosis patients were used to compare T2 map reconstruction times between the new subtraction method and the Euclidean norm minimization technique. Bloch equation simulations were used to create the lookup table for decay curve matching in both cases. Agreement of the two techniques used Bland-Altman analysis for investigating individual subsets of data and all image points in the five volumes (meta-analysis). The subtraction method resulted in an average reduction of computation time for single slices from 134 s (minimization method) to 0.44 s. Comparing T2 values between the subtraction and minimization methods resulted in a confidence interval ranging from -0.06 to 0.06 ms (95% of values were within ± 0.06 ms between the techniques). Using identical reconstruction code based on the subtraction method, inline T2 maps were produced from PD-T2 images directly on the scanner console. The excellent agreement between the two methods permits the subtraction technique to be interchanged with the previous method, reducing computation time and allowing inline T2 map reconstruction based on Bloch simulations directly on the scanner.
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Affiliation(s)
- Jeff Snyder
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Peter Seres
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Robert W Stobbe
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Justin G Grenier
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Penelope Smyth
- Department of Medicine, Division of Neurology, University of Alberta, Edmonton, Canada
| | - Gregg Blevins
- Department of Medicine, Division of Neurology, University of Alberta, Edmonton, Canada
| | - Alan H Wilman
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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Stern N, Radunsky D, Blumenfeld‐Katzir T, Chechik Y, Solomon C, Ben‐Eliezer N. Mapping of magnetic resonance imaging's transverse relaxation time at low signal-to-noise ratio using Bloch simulations and principal component analysis image denoising. NMR IN BIOMEDICINE 2022; 35:e4807. [PMID: 35899528 PMCID: PMC9787782 DOI: 10.1002/nbm.4807] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
High-resolution mapping of magnetic resonance imaging (MRI)'s transverse relaxation time (T2 ) can benefit many clinical applications by offering improved anatomic details, enhancing the ability to probe tissues' microarchitecture, and facilitating the identification of early pathology. Increasing spatial resolutions, however, decreases data's signal-to-noise ratio (SNR), particularly at clinical scan times. This impairs imaging quality, and the accuracy of subsequent radiological interpretation. Recently, principal component analysis (PCA) was employed for denoising diffusion-weighted MR images and was shown to be effective for improving parameter estimation in multiexponential relaxometry. This study combines the Marchenko-Pastur PCA (MP-PCA) signal model with the echo modulation curve (EMC) algorithm for denoising multiecho spin-echo (MESE) MRI data and improving the precision of EMC-generated single T2 relaxation maps. The denoising technique was validated on simulations, phantom scans, and in vivo brain and knee data. MESE scans were performed on a 3-T Siemens scanner. The acquired images were denoised using the MP-PCA algorithm and were then provided as input for the EMC T2 -fitting algorithm. Quantitative analysis of the denoising quality included comparing the standard deviation and coefficient of variation of T2 values, along with gold standard SNR estimation of the phantom scans. The presented denoising technique shows an increase in T2 maps' precision and SNR, while successfully preserving the morphological features of the tissue. Employing MP-PCA denoising as a preprocessing step decreases the noise-related variability of T2 maps produced by the EMC algorithm and thus increases their precision. The proposed method can be useful for a wide range of clinical applications by facilitating earlier detection of pathologies and improving the accuracy of patients' follow-up.
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Affiliation(s)
- Neta Stern
- Department of Biomedical EngineeringTel Aviv UniversityIsrael
| | - Dvir Radunsky
- Department of Biomedical EngineeringTel Aviv UniversityIsrael
| | | | - Yigal Chechik
- Department of OrthopedicsShamir Medical CenterBe'er Ya'akovIsrael
- Sackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Chen Solomon
- Department of Biomedical EngineeringTel Aviv UniversityIsrael
| | - Noam Ben‐Eliezer
- Department of Biomedical EngineeringTel Aviv UniversityIsrael
- Sagol School of NeuroscienceTel Aviv UniversityIsrael
- Center for Advanced Imaging Innovation and Research (CAIR)New York University School of MedicineNew YorkNew YorkUSA
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10
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Seginer A, Schmidt R. Phase-based fast 3D high-resolution quantitative T 2 MRI in 7 T human brain imaging. Sci Rep 2022; 12:14088. [PMID: 35982143 PMCID: PMC9388657 DOI: 10.1038/s41598-022-17607-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 07/28/2022] [Indexed: 12/04/2022] Open
Abstract
Magnetic resonance imaging (MRI) is a powerful and versatile technique that offers a range of physiological, diagnostic, structural, and functional measurements. One of the most widely used basic contrasts in MRI diagnostics is transverse relaxation time (T2)-weighted imaging, but it provides only qualitative information. Realizing quantitative high-resolution T2 mapping is imperative for the development of personalized medicine, as it can enable the characterization of diseases progression. While ultra-high-field (≥ 7 T) MRI offers the means to gain new insights by increasing the spatial resolution, implementing fast quantitative T2 mapping cannot be achieved without overcoming the increased power deposition and radio frequency (RF) field inhomogeneity at ultra-high-fields. A recent study has demonstrated a new phase-based T2 mapping approach based on fast steady-state acquisitions. We extend this new approach to ultra-high field MRI, achieving quantitative high-resolution 3D T2 mapping at 7 T while addressing RF field inhomogeneity and utilizing low flip angle pulses; overcoming two main ultra-high field challenges. The method is based on controlling the coherent transverse magnetization in a steady-state gradient echo acquisition; achieved by utilizing low flip angles, a specific phase increment for the RF pulses, and short repetition times. This approach simultaneously extracts both T2 and RF field maps from the phase of the signal. Prior to in vivo experiments, the method was assessed using a 3D head-shaped phantom that was designed to model the RF field distribution in the brain. Our approach delivers fast 3D whole brain images with submillimeter resolution without requiring special hardware, such as multi-channel transmit coil, thus promoting high usability of the ultra-high field MRI in clinical practice.
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Affiliation(s)
| | - Rita Schmidt
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel. .,The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel.
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11
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Quantification of Intra-Muscular Adipose Infiltration in Calf/Thigh MRI Using Fully and Weakly Supervised Semantic Segmentation. Bioengineering (Basel) 2022; 9:bioengineering9070315. [PMID: 35877366 PMCID: PMC9312115 DOI: 10.3390/bioengineering9070315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/29/2022] [Accepted: 07/08/2022] [Indexed: 11/16/2022] Open
Abstract
Purpose: Infiltration of fat into lower limb muscles is one of the key markers for the severity of muscle pathologies. The level of fat infiltration varies in its severity across and within patients, and it is traditionally estimated using visual radiologic inspection. Precise quantification of the severity and spatial distribution of this pathological process requires accurate segmentation of lower limb anatomy into muscle and fat. Methods: Quantitative magnetic resonance imaging (qMRI) of the calf and thigh muscles is one of the most effective techniques for estimating pathological accumulation of intra-muscular adipose tissue (IMAT) in muscular dystrophies. In this work, we present a new deep learning (DL) network tool for automated and robust segmentation of lower limb anatomy that is based on the quantification of MRI’s transverse (T2) relaxation time. The network was used to segment calf and thigh anatomies into viable muscle areas and IMAT using a weakly supervised learning process. A new disease biomarker was calculated, reflecting the level of abnormal fat infiltration and disease state. A biomarker was then applied on two patient populations suffering from dysferlinopathy and Charcot–Marie–Tooth (CMT) diseases. Results: Comparison of manual vs. automated segmentation of muscle anatomy, viable muscle areas, and intermuscular adipose tissue (IMAT) produced high Dice similarity coefficients (DSCs) of 96.4%, 91.7%, and 93.3%, respectively. Linear regression between the biomarker value calculated based on the ground truth segmentation and based on automatic segmentation produced high correlation coefficients of 97.7% and 95.9% for the dysferlinopathy and CMT patients, respectively. Conclusions: Using a combination of qMRI and DL-based segmentation, we present a new quantitative biomarker of disease severity. This biomarker is automatically calculated and, most importantly, provides a spatially global indication for the state of the disease across the entire thigh or calf.
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Bnaiahu N, Omer N, Wilczynski E, Levy S, Blumenfeld-Katzir T, Ben-Eliezer N. Correcting for imaging gradients-related bias of T 2 relaxation times at high-resolution MRI. Magn Reson Med 2022; 88:1806-1817. [PMID: 35666831 PMCID: PMC9544944 DOI: 10.1002/mrm.29319] [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] [Received: 01/04/2022] [Revised: 04/15/2022] [Accepted: 05/11/2022] [Indexed: 11/16/2022]
Abstract
Purpose High‐resolution animal imaging is an integral part of preclinical drug development and the investigation of diseases' pathophysiology. Quantitative mapping of T2 relaxation times (qT2) is a valuable tool for both preclinical and research applications, providing high sensitivity to subtle tissue pathologies. High‐resolution T2 mapping, however, suffers from severe underestimation of T2 values due to molecular diffusion. This affects both single‐echo and multi‐echo spin echo (SSE and MESE), on top of the well‐known contamination of MESE signals by stimulated echoes, and especially on high‐field and preclinical scanners in which high imaging gradients are used in comparison to clinical scanners. Methods Diffusion bias due to imaging gradients was analyzed by quantifying the effective b‐value for each coherence pathway in SSE and MESE protocols, and incorporating this information in a joint T2‐diffusion reconstruction algorithm. Validation was done on phantoms and in vivo mouse brain using a 9.4T and a 7T MRI scanner. Results Underestimation of T2 values due to strong imaging gradients can reach up to 70%, depending on scan parameters and on the sample's diffusion coefficient. The algorithm presented here produced T2 values that agreed with reference spectroscopic measurements, were reproducible across scan settings, and reduced the average bias of T2 values from −33.5 ± 20.5% to −0.1 ± 3.6%. Conclusions A new joint T2‐diffusion reconstruction algorithm is able to negate imaging gradient–related underestimation of T2 values, leading to reliable mapping of T2 values at high resolutions. Click here for author‐reader discussions
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Affiliation(s)
- Natalie Bnaiahu
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Noam Omer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Ella Wilczynski
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Shir Levy
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| | | | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.,Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, USA
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13
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Shpringer G, Bendahan D, Ben-Eliezer N. Accelerated reconstruction of dictionary-based T 2 relaxation maps based on dictionary compression and gradient descent search algorithms. Magn Reson Imaging 2021; 87:56-66. [PMID: 34973389 DOI: 10.1016/j.mri.2021.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 11/19/2021] [Accepted: 12/22/2021] [Indexed: 11/18/2022]
Abstract
Background Quantitative T2-relaxation-based contrast maps have shown to be highly beneficial for clinical diagnosis and follow-up. The generation of quantitative maps, however, is impaired by long acquisition times, and time-consuming post-processing schemes. The EMC platform is a dictionary-based technique, which involves simulating theoretical signal curves for different physical and experimental values, followed by matching the experimentally acquired signals to the set simulated ones. Purpose Although the EMC technique has shown to produce accurate T2 maps, it involves computationally intensive post-processing procedures. In this work we present an approach for accelerating the reconstruction of T2 relaxation maps. Methods This work presents two alternative post-processing approaches for accelerating the reconstruction of EMC-based T2 relaxation maps. These are (a) Dictionary compression using principal component analysis (PCA) and (b) gradient-descent search algorithm. Additional acceleration was achieved by finding the optimal MATLAB C++ compiler. The utility of the two suggested approaches was examined by calculating the relative error, produced by each technique. Results Gradient descent method was in perfect agreement with the ground truth exhaustive search matching process. PCA based acceleration produced root mean square error (RMSE) of up to 4% compared to exhaustive matching process. Overall acceleration of x16 was achieved using gradient descent in addition to x7 acceleration by choosing the optimal MATLAB C++ compiler. Conclusions Postprocessing of EMC-based T2 relaxation maps can be accelerated without impairing the accuracy of the ensuing T2 values.
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Affiliation(s)
- Guy Shpringer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - David Bendahan
- Aix Marseille University, CNRS UMR 7339, CRMBM, Marseille, France
| | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel; Center for Advanced Imaging Innovation and Research (CAI2R), New York University Langone Medical Center, New York, NY, USA.
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14
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Chechik Y, Beit Ner E, Lysyy O, Tal S, Stern N, Agar G, Beer Y, Ben-Eliezer N, Lindner D. Post-Run T 2 Mapping Changes in Knees of Adolescent Basketball Players. Cartilage 2021; 13:707S-717S. [PMID: 34128410 PMCID: PMC8808782 DOI: 10.1177/19476035211021891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE While articular cartilage defects are common incidental findings among adult athletes, the effect of running on the cartilage of adolescent athletes have rarely been assessed. This study aims to assess the variations in the articular cartilage of the knees in healthy adolescent basketball players using quantitative T2 MRI (magnetic resonance imaging). DESIGN Fifteen adolescent basketball players were recruited (13.8 ± 0.5 years old). Girls were excluded to avoid potential gender-related confounding effects. Players underwent a pre-run MRI scan of both knees. All participants performed a 30-minute run on a treadmill. Within 15 minutes after completion of their run, players underwent a second, post-run MRI scan. Quantitative T2 maps were generated using the echo modulation curve (EMC) algorithm. Pre-run scans and post-run scans were compared using paired t test. RESULTS Participants finished their 30-minute run with a mean running distance of 5.77 ± 0.42 km. Pre-run scans analysis found statistically significant (P < 0.05) changes in 3 regions of the knee lateral compartment representing the cartilaginous tissue. No differences were found in the knee medial compartment. Post-run analysis showed lower T2 values in the medial compartment compared to the pre-run scans in several weight-bearing regions: femoral condyle central (pre/post mean values of 33.9/32.2 ms, P = 0.020); femoral condyle posterior (38.1/36.8 ms, P = 0.038); and tibial plateau posterior (34.1/31.0 ms, P < 0.001). The lateral regions did not show any significant changes. CONCLUSIONS Running leads to microstructural changes in the articular cartilage in several weight-bearing areas of the medial compartment, both in the femoral and the tibial cartilage.
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Affiliation(s)
- Yigal Chechik
- Department of Orthopedic Surgery,
Yitzhak Shamir Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of
Medicine, Tel Aviv University, Tel Aviv, Israel,Yigal Chechik, Department of Orthopedic
Surgery, Yitzhak Shamir Medical Center, Zerifin 70300, Israel.
| | - Eran Beit Ner
- Department of Orthopedic Surgery,
Yitzhak Shamir Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of
Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Oleg Lysyy
- Department of Imaging, Yitzhak Shamir
Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of Medicine,
Tel-Aviv University, Tel Aviv, Israel
| | - Sigal Tal
- Department of Imaging, Yitzhak Shamir
Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of Medicine,
Tel-Aviv University, Tel Aviv, Israel
| | - Neta Stern
- Department of Biomedical Engineering,
Tel Aviv University, Tel Aviv, Israel
| | - Gabriel Agar
- Department of Orthopedic Surgery,
Yitzhak Shamir Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of
Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yiftach Beer
- Department of Orthopedic Surgery,
Yitzhak Shamir Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of
Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Noam Ben-Eliezer
- Department of Biomedical Engineering,
Tel Aviv University, Tel Aviv, Israel,Sagol School of Neuroscience, Tel Aviv
University, Tel Aviv, Israel,Center for Advanced Imaging Innovation
and Research (CAI2R), New-York University Langone Medical Center, New York, NY,
USA
| | - Dror Lindner
- Department of Orthopedic Surgery,
Yitzhak Shamir Medical Center, Zerifin, Israel, affiliated to the Sackler Faculty of
Medicine, Tel Aviv University, Tel Aviv, Israel
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15
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Radunsky D, Stern N, Nassar J, Tsarfaty G, Blumenfeld-Katzir T, Ben-Eliezer N. Quantitative platform for accurate and reproducible assessment of transverse (T 2 ) relaxation time. NMR IN BIOMEDICINE 2021; 34:e4537. [PMID: 33993573 DOI: 10.1002/nbm.4537] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/02/2021] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
MRI's transverse relaxation time (T2 ) is sensitive to tissues' composition and pathological state. While variations in T2 values can be used as clinical biomarkers, it is challenging to quantify this parameter in vivo due to the complexity of the MRI signal model, differences in protocol implementations, and hardware imperfections. Herein, we provide a detailed analysis of the echo modulation curve (EMC) platform, offering accurate and reproducible mapping of T2 values, from 2D multi-slice multi-echo spin-echo (MESE) protocols. Computer simulations of the full Bloch equations are used to generate an advanced signal model, which accounts for stimulated echoes and transmit field (B1+ ) inhomogeneities. In addition to quantifying T2 values, the EMC platform also provides proton density (PD) maps, and fat-water fraction maps. The algorithm's accuracy, reproducibility, and insensitivity to T1 values are validated on a phantom constructed by the National Institute of Standards and Technology and on in vivo human brains. EMC-derived T2 maps show excellent agreement with ground truth values for both in vitro and in vivo models. Quantitative values are accurate and stable across scan settings and for the physiological range of T2 values, while showing robustness to main field (B0 ) inhomogeneities, to variations in T1 relaxation time, and to magnetization transfer. Extension of the algorithm to two-component fitting yields accurate fat and water T2 maps along with their relative fractions, similar to a reference three-point Dixon technique. Overall, the EMC platform allows to generate accurate and stable T2 maps, with a full brain coverage using a standard MESE protocol and at feasible scan times. The utility of EMC-based T2 maps was demonstrated on several clinical applications, showing robustness to variations in other magnetic properties. The algorithm is available online as a full stand-alone package, including an intuitive graphical user interface.
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Affiliation(s)
- Dvir Radunsky
- Department of Biomedical Engineering, Tel Aviv University, Israel
| | - Neta Stern
- Department of Biomedical Engineering, Tel Aviv University, Israel
| | - Jannette Nassar
- Department of Biomedical Engineering, Tel Aviv University, Israel
| | - Galia Tsarfaty
- Department of Diagnostic Imaging, Sheba Medical Center, Ramat Gan, Israel
| | | | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel Aviv University, Israel
- Sagol School of Neuroscience, Tel Aviv University, Israel
- Center for Advanced Imaging Innovation and Research (CAI2R), New York University Langone Medical Center, New York, New York, USA
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16
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Fatemi Y, Danyali H, Helfroush MS, Amiri H. Fast T 2 mapping using multi-echo spin-echo MRI: A linear order approach. Magn Reson Med 2020; 84:2815-2830. [PMID: 32430979 PMCID: PMC7402028 DOI: 10.1002/mrm.28309] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 04/13/2020] [Accepted: 04/15/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE Multi-echo spin-echo sequence is commonly used for T2 mapping. The estimated values using conventional exponential fit, however, are hampered by stimulated and indirect echoes leading to overestimation of T2 . Here, we present fast analysis of multi-echo spin-echo (FAMESE) as a novel approach to decrease the complexity of the search space, which leads to accelerated measurement of T2 . METHODS We developed FAMESE based on mathematical analysis of the Bloch equations in which the search space dimension decreased to only one. Then, we tested it in both phantom and human brain. Bland-Altman plot was used to assess the agreement between the estimated T2 values from FAMESE and the ones estimated from single-echo spin-echo sequence. The reliability of FAMESE was assessed by intraclass correlation coefficients. In addition, we investigated the noise stability of the method in synthetic and experimental data. RESULTS In both phantom and healthy participants, FAMESE provided accelerated and SNR-resistant T2 maps. The FAMESE had a very good agreement with the single-echo spin echo for the whole range of T2 values. The intraclass correlation coefficient values for FAMESE were excellent (ie, 0.9998 and 0.9860 < intraclass correlation coefficient < 0.9942 for the phantom and humans, respectively). CONCLUSION Our developed method FAMESE could be considered as a candidate for rapid T2 mapping with a clinically feasible scan time.
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Affiliation(s)
- Yaghoub Fatemi
- Department of Electrical and Electronics EngineeringShiraz University of TechnologyShirazIran
| | - Habibollah Danyali
- Department of Electrical and Electronics EngineeringShiraz University of TechnologyShirazIran
| | | | - Houshang Amiri
- Neuroscience Research CenterInstitute of NeuropharmacologyKerman University of Medical SciencesKermanIran
- Department of Radiology and Nuclear MedicineVU University Medical CenterAmsterdamthe Netherlands
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17
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Kirov II, Tal A. Potential clinical impact of multiparametric quantitative MR spectroscopy in neurological disorders: A review and analysis. Magn Reson Med 2020; 83:22-44. [PMID: 31393032 PMCID: PMC6814297 DOI: 10.1002/mrm.27912] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/06/2019] [Accepted: 06/29/2019] [Indexed: 12/12/2022]
Abstract
PURPOSE Unlike conventional MR spectroscopy (MRS), which only measures metabolite concentrations, multiparametric MRS also quantifies their longitudinal (T1 ) and transverse (T2 ) relaxation times, as well as the radiofrequency transmitter inhomogeneity (B1+ ). To test whether knowledge of these additional parameters can improve the clinical utility of brain MRS, we compare the conventional and multiparametric approaches in terms of expected classification accuracy in differentiating controls from patients with neurological disorders. THEORY AND METHODS A literature review was conducted to compile metabolic concentrations and relaxation times in a wide range of neuropathologies and regions of interest. Simulations were performed to construct receiver operating characteristic curves and compute the associated areas (area under the curve) to examine the sensitivity and specificity of MRS for detecting each pathology in each region. Classification accuracy was assessed using metabolite concentrations corrected using population-averages for T1 , T2 , and B1+ (conventional MRS); using metabolite concentrations corrected using per-subject values (multiparametric MRS); and using an optimal linear multiparametric estimator comprised of the metabolites' concentrations and relaxation constants (multiparametric MRS). Additional simulations were conducted to find the minimal intra-subject precision needed for each parameter. RESULTS Compared with conventional MRS, multiparametric approaches yielded area under the curve improvements for almost all neuropathologies and regions of interest. The median area under the curve increased by 0.14 over the entire dataset, and by 0.24 over the 10 instances with the largest individual increases. CONCLUSIONS Multiparametric MRS can substantially improve the clinical utility of MRS in diagnosing and assessing brain pathology, motivating the design and use of novel multiparametric sequences.
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Affiliation(s)
- Ivan I. Kirov
- Center for Advanced Imaging Innovation and Research (CAIR), Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, Department of Radiology, 660 1 Avenue, New York, NY 10016, United States of America
| | - Assaf Tal
- Department of Chemical and Biological Physics, Weizmann Institute of Science, 234 Herzel St., Rehovot 7610001, Israel
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18
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Hagiwara A, Kamagata K, Shimoji K, Yokoyama K, Andica C, Hori M, Fujita S, Maekawa T, Irie R, Akashi T, Wada A, Suzuki M, Abe O, Hattori N, Aoki S. White Matter Abnormalities in Multiple Sclerosis Evaluated by Quantitative Synthetic MRI, Diffusion Tensor Imaging, and Neurite Orientation Dispersion and Density Imaging. AJNR Am J Neuroradiol 2019; 40:1642-1648. [PMID: 31515218 DOI: 10.3174/ajnr.a6209] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 07/28/2019] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE A number of MR-derived quantitative metrics have been suggested to assess the pathophysiology of MS, but the reports about combined analyses of these metrics are scarce. Our aim was to assess the spatial distribution of parameters for white matter myelin and axon integrity in patients with relapsing-remitting MS by multiparametric MR imaging. MATERIALS AND METHODS Twenty-four patients with relapsing-remitting MS and 24 age- and sex-matched controls were prospectively scanned by quantitative synthetic and 2-shell diffusion MR imaging. Synthetic MR imaging data were used to retrieve relaxometry parameters (R1 and R2 relaxation rates and proton density) and myelin volume fraction. Diffusion tensor metrics (fractional anisotropy and mean, axial, and radial diffusivity) and neurite orientation and dispersion index metrics (intracellular volume fraction, isotropic volume fraction, and orientation dispersion index) were retrieved from diffusion MR imaging data. These data were analyzed using Tract-Based Spatial Statistics. RESULTS Patients with MS showed significantly lower fractional anisotropy and myelin volume fraction and higher isotropic volume fraction in widespread white matter areas. Areas with different isotropic volume fractions were included within areas with lower fractional anisotropy. Myelin volume fraction showed no significant difference in some areas with significantly decreased fractional anisotropy in MS, including in the genu of the corpus callosum and bilateral anterior corona radiata, whereas myelin volume fraction was significantly decreased in some areas where fractional anisotropy showed no significant difference, including the bilateral posterior limb of the internal capsule, external capsule, sagittal striatum, fornix, and uncinate fasciculus. CONCLUSIONS We found differences in spatial distribution of abnormality in fractional anisotropy, isotropic volume fraction, and myelin volume fraction distribution in MS, which might be useful for characterizing white matter in patients with MS.
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Affiliation(s)
- A Hagiwara
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
- Department of Radiology (A.H., S.F., T.M., R.I., O.A.), Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - K Kamagata
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
| | - K Shimoji
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
- Department of Diagnostic Radiology (K.S.), Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan
| | - K Yokoyama
- Neurology (K.Y., N.H.), Juntendo University School of Medicine, Tokyo, Japan
| | - C Andica
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
| | - M Hori
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
- Department of Radiology (M.H.), Toho University Omori Medical Center, Tokyo, Japan
| | - S Fujita
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
- Department of Radiology (A.H., S.F., T.M., R.I., O.A.), Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - T Maekawa
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
- Department of Radiology (A.H., S.F., T.M., R.I., O.A.), Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - R Irie
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
- Department of Radiology (A.H., S.F., T.M., R.I., O.A.), Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - T Akashi
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
| | - A Wada
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
| | - M Suzuki
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
| | - O Abe
- Department of Radiology (A.H., S.F., T.M., R.I., O.A.), Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - N Hattori
- Neurology (K.Y., N.H.), Juntendo University School of Medicine, Tokyo, Japan
| | - S Aoki
- From the Departments of Radiology (A.H., K.K., K.S., C.A., M.H., S.F., T.M., R.I., T.A., A.W., M.S., S.A.)
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Radunsky D, Blumenfeld-Katzir T, Volovyk O, Tal A, Barazany D, Tsarfaty G, Ben-Eliezer N. Analysis of magnetization transfer (MT) influence on quantitative mapping of T 2 relaxation time. Magn Reson Med 2019; 82:145-158. [PMID: 30860287 DOI: 10.1002/mrm.27704] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 01/28/2019] [Accepted: 01/30/2019] [Indexed: 12/22/2022]
Abstract
PURPOSE Multi-echo spin-echo (MESE) protocol is the most effective tool for mapping T2 relaxation in vivo. Still, MESE extensive use of radiofrequency pulses causes magnetization transfer (MT)-related bias of the water signal, instigated by the presence of macromolecules (MMP). Here, we analyze the effects of MT on MESE signal, alongside their impact on quantitative T2 measurements. METHODS Study used 3 models: in vitro urea phantom, ex vivo horse brain, and in vivo human brain. MT ratio (MTR) was measured between single-SE and MESE protocols under different scan settings including varying echo train lengths, number of slices, and inter-slice gap. MTR and T2 values were extracted for each model and protocol. RESULTS MT interactions biased MESE signals, and in certain settings, the corresponding T2 values. T2 underestimation of up to 4.3% was found versus single-SE values in vitro and up to 13.8% ex vivo, correlating with the MMP content. T2 bias originated from intra-slice saturation of the MMP, rather than from indirect saturation in multi-slice acquisitions. MT-related signal attenuation was caused by slice crosstalk and/or partial T1 recovery, whereas smaller contribution was caused by MMP interactions. Inter-slice gap had a similar effect on in vivo MTR (21.2%), in comparison to increasing the number of slices (18.9%). CONCLUSIONS MT influences MESE protocols either by uniformly attenuating the entire echo train or by cumulatively attenuating the signal along the train. Although both processes depend on scan settings and MMP content, only the latter will cause underestimation of T2 .
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Affiliation(s)
- Dvir Radunsky
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | | | - Osnat Volovyk
- Department of Chemical Physics, The Weizmann Institute, Rehovot, Israel
| | - Assaf Tal
- Department of Chemical Physics, The Weizmann Institute, Rehovot, Israel
| | - Daniel Barazany
- Strauss computational neuroimaging center, Tel Aviv University, Tel Aviv, Israel
| | - Galia Tsarfaty
- Department of Diagnostic Imaging, Sheba Medical Center, Ramat Gan, Israel
| | - Noam Ben-Eliezer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.,Center for Advanced Imaging Innovation and Research (CAI2R), NewYork University Langone Medical Center, New York, New York
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20
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DeMarshall C, Goldwaser EL, Sarkar A, Godsey GA, Acharya NK, Thayasivam U, Belinka BA, Nagele RG. Autoantibodies as diagnostic biomarkers for the detection and subtyping of multiple sclerosis. J Neuroimmunol 2017; 309:51-57. [PMID: 28601288 DOI: 10.1016/j.jneuroim.2017.05.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/18/2017] [Accepted: 05/18/2017] [Indexed: 12/19/2022]
Abstract
The goal of this preliminary proof-of-concept study was to use human protein microarrays to identify blood-based autoantibody biomarkers capable of diagnosing multiple sclerosis (MS). Using sera from 112 subjects, including 51 MS subjects, autoantibody biomarkers effectively differentiated MS subjects from age- and gender-matched normal and breast cancer controls with 95.0% and 100% overall accuracy, but not from subjects with Parkinson's disease. Autoantibody biomarkers were also useful in distinguishing subjects with the relapsing-remitting form of MS from those with the secondary progressive subtype. These results demonstrate that autoantibodies can be used as noninvasive blood-based biomarkers for the detection and subtyping of MS.
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Affiliation(s)
- Cassandra DeMarshall
- Biomarker Discovery Center, New Jersey Institute for Successful Aging, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Department of Geriatrics and Gerontology, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA
| | - Eric L Goldwaser
- Biomarker Discovery Center, New Jersey Institute for Successful Aging, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Department of Geriatrics and Gerontology, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA
| | - Abhirup Sarkar
- Biomarker Discovery Center, New Jersey Institute for Successful Aging, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Department of Geriatrics and Gerontology, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
| | - George A Godsey
- Biomarker Discovery Center, New Jersey Institute for Successful Aging, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Department of Geriatrics and Gerontology, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
| | - Nimish K Acharya
- Department of Neurosurgery, Penn Center for Brain Injury and Repair, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | - Robert G Nagele
- Biomarker Discovery Center, New Jersey Institute for Successful Aging, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA; Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA; Durin Technologies, Inc., New Brunswick, NJ, USA.
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