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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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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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Accelerated Simultaneous T 2 and T 2* Mapping of Multiple Sclerosis Lesions Using Compressed Sensing Reconstruction of Radial RARE-EPI MRI. Tomography 2023; 9:299-314. [PMID: 36828376 PMCID: PMC9960840 DOI: 10.3390/tomography9010024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
(1) Background: Radial RARE-EPI MRI facilitates simultaneous T2 and T2* mapping (2in1-RARE-EPI). With modest undersampling (R = 2), the speed gain of 2in1-RARE-EPI relative to Multi-Spin-Echo and Multi-Gradient-Recalled-Echo references is limited. Further reduction in scan time is crucial for clinical studies investigating T2 and T2* as imaging biomarkers. We demonstrate the feasibility of further acceleration, utilizing compressed sensing (CS) reconstruction of highly undersampled 2in1-RARE-EPI. (2) Methods: Two-fold radially-undersampled 2in1-RARE-EPI data from phantoms, healthy volunteers (n = 3), and multiple sclerosis patients (n = 4) were used as references, and undersampled (Rextra = 1-12, effective undersampling Reff = 2-24). For each echo time, images were reconstructed using CS-reconstruction. For T2 (RARE module) and T2* mapping (EPI module), a linear least-square fit was applied to the images. T2 and T2* from CS-reconstruction of undersampled data were benchmarked against values from CS-reconstruction of the reference data. (3) Results: We demonstrate accelerated simultaneous T2 and T2* mapping using undersampled 2in1-RARE-EPI with CS-reconstruction is feasible. For Rextra = 6 (TA = 01:39 min), the overall MAPE was ≤8% (T2*) and ≤4% (T2); for Rextra = 12 (TA = 01:06 min), the overall MAPE was <13% (T2*) and <5% (T2). (4) Conclusion: Substantial reductions in scan time are achievable for simultaneous T2 and T2* mapping of the brain using highly undersampled 2in1-RARE-EPI with CS-reconstruction.
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Kraiger M, Klein-Rodewald T, Rathkolb B, Calzada-Wack J, Sanz-Moreno A, Fuchs H, Wolf E, Gailus-Durner V, de Angelis MH. Monitoring longitudinal disease progression in a novel murine Kit tumor model using high-field MRI. Sci Rep 2022; 12:14608. [PMID: 36028522 PMCID: PMC9418174 DOI: 10.1038/s41598-022-17880-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/02/2022] [Indexed: 11/09/2022] Open
Abstract
Animal models are an indispensable platform used in various research disciplines, enabling, for example, studies of basic biological mechanisms, pathological processes and new therapeutic interventions. In this study, we applied magnetic resonance imaging (MRI) to characterize the clinical picture of a novel N-ethyl-N-nitrosourea-induced Kit-mutant mouse in vivo. Seven C3H KitN824K/WT mutant animals each of both sexes and their littermates were monitored every other month for a period of twelve months. MRI relaxometry data of hematopoietic bone marrow and splenic tissue as well as high-resolution images of the gastrointestinal organs were acquired. Compared with controls, the mutants showed a dynamic change in the shape and volume of the cecum and enlarged Peyer´s patches were identified throughout the entire study. Mammary tumors were observed in the majority of mutant females and were first detected at eight months of age. Using relaxation measurements, a substantial decrease in longitudinal relaxation times in hematopoietic tissue was detected in mutants at one year of age. In contrast, transverse relaxation time of splenic tissue showed no differences between genotypes, except in two mutant mice, one of which had leukemia and the other hemangioma. In this study, in vivo MRI was used for the first time to thoroughly characterize the evolution of systemic manifestations of a novel Kit-induced tumor model and to document the observable organ-specific disease cascade.
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Affiliation(s)
- Markus Kraiger
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.
| | - Tanja Klein-Rodewald
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Birgit Rathkolb
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Julia Calzada-Wack
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Adrián Sanz-Moreno
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Helmut Fuchs
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Valérie Gailus-Durner
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Hrabě de Angelis
- Institute of Experimental Genetics, German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Chair of Experimental Genetics, TUM School of Life Sciences, Technische Universität München, Freising, Germany
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Fast, Accurate, and Robust T2 Mapping of Articular Cartilage by Neural Networks. Diagnostics (Basel) 2022; 12:diagnostics12030688. [PMID: 35328240 PMCID: PMC8947694 DOI: 10.3390/diagnostics12030688] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/25/2022] [Accepted: 03/09/2022] [Indexed: 12/31/2022] Open
Abstract
For T2 mapping, the underlying mono-exponential signal decay is traditionally quantified by non-linear Least-Squares Estimation (LSE) curve fitting, which is prone to outliers and computationally expensive. This study aimed to validate a fully connected neural network (NN) to estimate T2 relaxation times and to assess its performance versus LSE fitting methods. To this end, the NN was trained and tested in silico on a synthetic dataset of 75 million signal decays. Its quantification error was comparatively evaluated against three LSE methods, i.e., traditional methods without any modification, with an offset, and one with noise correction. Following in-situ acquisition of T2 maps in seven human cadaveric knee joint specimens at high and low signal-to-noise ratios, the NN and LSE methods were used to estimate the T2 relaxation times of the manually segmented patellofemoral cartilage. In-silico modeling at low signal-to-noise ratio indicated significantly lower quantification error for the NN (by medians of 6−33%) than for the LSE methods (p < 0.001). These results were confirmed by the in-situ measurements (medians of 10−35%). T2 quantification by the NN took only 4 s, which was faster than the LSE methods (28−43 s). In conclusion, NNs provide fast, accurate, and robust quantification of T2 relaxation times.
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Cao T, Ma S, Wang N, Gharabaghi S, Xie Y, Fan Z, Hogg E, Wu C, Han F, Tagliati M, Haacke EM, Christodoulou AG, Li D. Three-dimensional simultaneous brain mapping of T1, T2, T2∗ and magnetic susceptibility with MR Multitasking. Magn Reson Med 2022; 87:1375-1389. [PMID: 34708438 PMCID: PMC8776611 DOI: 10.1002/mrm.29059] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 09/08/2021] [Accepted: 10/07/2021] [Indexed: 01/24/2023]
Abstract
PURPOSE To develop a new technique that enables simultaneous quantification of whole-brain T1 , T2 , T 2 ∗ , as well as susceptibility and synthesis of six contrast-weighted images in a single 9.1-minute scan. METHODS The technique uses hybrid T2 -prepared inversion-recovery pulse modules and multi-echo gradient-echo readouts to collect k-space data with various T1, T2, and T 2 ∗ weightings. The underlying image is represented as a six-dimensional low-rank tensor consisting of three spatial dimensions and three temporal dimensions corresponding to T1 recovery, T2 decay, and multi-echo behaviors, respectively. Multiparametric maps were fitted from reconstructed image series. The proposed method was validated on phantoms and healthy volunteers, by comparing quantitative measurements against corresponding reference methods. The feasibility of generating six contrast-weighted images was also examined. RESULTS High quality, co-registered T1 , T2 , and T 2 ∗ susceptibility maps were generated that closely resembled the reference maps. Phantom measurements showed substantial consistency (R2 > 0.98) with the reference measurements. Despite the significant differences of T1 (p < .001), T2 (p = .002), and T 2 ∗ (p = 0.008) between our method and the references for in vivo studies, excellent agreement was achieved with all intraclass correlation coefficients greater than 0.75. No significant difference was found for susceptibility (p = .900). The framework is also capable of synthesizing six contrast-weighted images. CONCLUSION The MR Multitasking-based 3D brain mapping of T1 , T2 , T 2 ∗ , and susceptibility agrees well with the reference and is a promising technique for multicontrast and quantitative imaging.
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Affiliation(s)
- Tianle Cao
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Sen Ma
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Nan Wang
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Sara Gharabaghi
- Magnetic Resonance Innovations, Inc., Bingham Farms, MI, USA
| | - Yibin Xie
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Zhaoyang Fan
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Elliot Hogg
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Chaowei Wu
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Fei Han
- Siemens Medical Solutions USA, Inc., Los Angeles, California, USA
| | - Michele Tagliati
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - E. Mark Haacke
- Magnetic Resonance Innovations, Inc., Bingham Farms, MI, USA
- Department of Radiology, Wayne State University School of Medicine, Detroit, MI, USA
- The MRI Institute for Biomedical Research, Bingham Farms, MI, USA
| | - Anthony G. Christodoulou
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Department of Bioengineering, University of California, Los Angeles, California, USA
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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: 19] [Impact Index Per Article: 6.3] [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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Freitas AC, Gaspar AS, Sousa I, Teixeira RPAG, Hajnal JV, Nunes RG. Improving B 1 + parametric estimation in the brain from multispin-echo sequences using a fusion bootstrap moves solver. Magn Reson Med 2021; 86:2426-2440. [PMID: 34231250 DOI: 10.1002/mrm.28878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 05/08/2021] [Accepted: 05/11/2021] [Indexed: 11/10/2022]
Abstract
PURPOSE To simultaneously estimate the B 1 + field (along with the T2 ) in the brain with multispin-echo (MSE) sequences and dictionary matching. METHODS T2 mapping provides clinically relevant information such as in the assessment of brain degenerative diseases. It is commonly obtained with MSE sequences, and accuracy can be further improved by matching the MSE signal to a precomputed dictionary of echo-modulation curves. For additional T1 quantification, transmit B 1 + field knowledge is also required. Preliminary work has shown that although simultaneous brain B 1 + estimation along with T2 is possible, it presents a bimodal distribution with the main peak coinciding with the true value. By taking advantage of this, the B 1 + maps are expected to be spatially smooth by applying an iterative method that takes into account each pixel neighborhood known as the fusion bootstrap moves solver (FBMS). The effect of the FBMS on B 1 + accuracy and piecewise smoothness is investigated and different spatial regularization levels are compared. Total variation regularization was used for both B 1 + and T2 simultaneous estimation because of its simplicity as an initial proof-of-concept; future work could explore non edge-preserving regularization independently for B 1 + . RESULTS Improvements in B 1 + accuracy (up to 45.37% and 16.81% B 1 + error decrease) and recovery of spatially homogeneous maps are shown in simulations and in vivo 3.0T brain data, respectively. CONCLUSION Accurate B 1 + estimated values can be obtained from widely available MSE sequences while jointly estimating T2 maps with the use of echo-modulation curve matching and FBMS at no further cost.
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Affiliation(s)
- Andreia C Freitas
- Institute for Systems and Robotics (ISR-Lisboa)/LaRSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Andreia S Gaspar
- Institute for Systems and Robotics (ISR-Lisboa)/LaRSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Inês Sousa
- Institute for Systems and Robotics (ISR-Lisboa)/LaRSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Rui P A G Teixeira
- Centre for the Developing Brain, School of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Joseph V Hajnal
- Centre for the Developing Brain, School of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Rita G Nunes
- Institute for Systems and Robotics (ISR-Lisboa)/LaRSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,Centre for the Developing Brain, School of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
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Raudner M, Schreiner MM, Hilbert T, Kober T, Weber M, Szelényi A, Windhager R, Juras V, Trattnig S. Clinical implementation of accelerated T 2 mapping: Quantitative magnetic resonance imaging as a biomarker for annular tear and lumbar disc herniation. Eur Radiol 2021; 31:3590-3599. [PMID: 33274406 PMCID: PMC8128819 DOI: 10.1007/s00330-020-07538-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 10/20/2020] [Accepted: 11/17/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVES This study evaluates GRAPPATINI, an accelerated T2 mapping sequence combining undersampling and model-based reconstruction to facilitate the clinical implementation of T2 mapping of the lumbar intervertebral disc. METHODS Fifty-eight individuals (26 females, 32 males, age 23.3 ± 8.0 years) were prospectively examined at 3 T. This cohort study consisted of 19 patients, 20 rowers, and 19 volunteers. GRAPPATINI was conducted with the same parameters as a conventional 2D multi-echo spin-echo (MESE) sequence in 02:27 min instead of 13:18 min. Additional T2 maps were calculated after discarding the first echo (T2-WO1ST) and only using even echoes (T2-EVEN). Segmentation was done on the four most central slices. The resulting T2 values were compared for all four measurements. RESULTS T2-GRAPPATINI, T2-MESE, T2-EVEN, and T2-WO1ST of the nucleus pulposus of normal discs differed significantly from those of bulging discs or herniated discs (all p < 0.001). For the posterior annular region, only T2-GRAPPATINI showed a significant difference (p = 0.011) between normal and herniated discs. There was a significant difference between T2-GRAPPATINI, T2-MESE, T2-EVEN, and T2-WO1ST of discs with and without an annular tear for the nucleus pulposus (all p < 0.001). The nucleus pulposus' T2 at different degeneration states showed significant differences between all group comparisons of Pfirrmann grades for T2-GRAPPATINI (p = 0.000-0.018), T2-MESE (p = 0.000-0.015), T2-EVEN (p = 0.000-0.019), and T2-WO1ST (p = 0.000-0.015). CONCLUSIONS GRAPPATINI facilitates the use of T2 values as quantitative imaging biomarkers to detect disc pathologies such as degeneration, lumbar disc herniation, and annular tears while simultaneously shortening the acquisition time from 13:18 to 2:27 min. KEY POINTS • T2-GRAPPATINI, T2-MESE, T2-EVEN, and T2-WO1ST of the nucleus pulposus of normal discs differed significantly from those of discs with bulging or herniation (all p < 0.001). • The investigated T2 mapping techniques differed significantly in discs with and without annular tearing (all p < 0.001). • The nucleus pulposus' T2 showed significant differences between different stages of degeneration in all group comparisons for T2-GRAPPATINI (p = 0.000-0.018), T2-MESE (p = 0.000-0.015), T2-EVEN (p = 0.000-0.019), and T2-WO1ST (p = 0.000-0.015).
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Affiliation(s)
- Marcus Raudner
- Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
- Christian Doppler Laboratory for Clinical Molecular MR Imaging (MOLIMA), Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Vienna, Austria
| | - Markus M Schreiner
- Department of Orthopaedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria
| | - Tom Hilbert
- Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- LTS5, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Tobias Kober
- Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- LTS5, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Michael Weber
- Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Anna Szelényi
- Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Reinhard Windhager
- Department of Orthopaedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria
| | - Vladimir Juras
- Christian Doppler Laboratory for Clinical Molecular MR Imaging (MOLIMA), Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Vienna, Austria
- Department of Imaging Methods, Institute of Measurement Science, Bratislava, Slovakia
| | - Siegfried Trattnig
- Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.
- Christian Doppler Laboratory for Clinical Molecular MR Imaging (MOLIMA), Department of Biomedical Imaging and Image-guided Therapy, High Field MR Center, Medical University of Vienna, Vienna, Austria.
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10
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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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11
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Ma S, Wang N, Fan Z, Kaisey M, Sicotte NL, Christodoulou AG, Li D. Three-dimensional whole-brain simultaneous T1, T2, and T1ρ quantification using MR Multitasking: Method and initial clinical experience in tissue characterization of multiple sclerosis. Magn Reson Med 2020; 85:1938-1952. [PMID: 33107126 DOI: 10.1002/mrm.28553] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE To develop a 3D whole-brain simultaneous T1/T2/T1ρ quantification method with MR Multitasking that provides high quality, co-registered multiparametric maps in 9 min. METHODS MR Multitasking conceptualizes T1/T2/T1ρ relaxations as different time dimensions, simultaneously resolving all three dimensions with a low-rank tensor image model. The proposed method was validated on a phantom and in healthy volunteers, comparing quantitative measurements against corresponding reference methods and evaluating the scan-rescan repeatability. Initial clinical validation was performed in age-matched relapsing-remitting multiple sclerosis (RRMS) patients to examine the feasibility of quantitative tissue characterization and to compare with the healthy control cohort. The feasibility of synthesizing six contrast-weighted images was also examined. RESULTS Our framework produced high quality, co-registered T1/T2/T1ρ maps that closely resemble the reference maps. Multitasking T1/T2/T1ρ measurements showed substantial agreement with reference measurements on the phantom and in healthy controls. Bland-Altman analysis indicated good in vivo repeatability of all three parameters. In RRMS patients, lesions were conspicuously delineated on all three maps and on four synthetic weighted images (T2-weighted, T2-FLAIR, double inversion recovery, and a novel "T1ρ-FLAIR" contrast). T1 and T2 showed significant differences for normal appearing white matter between patients and controls, while T1ρ showed significant differences for normal appearing white matter, cortical gray matter, and deep gray matter. The combination of three parameters significantly improved the differentiation between RRMS patients and healthy controls, compared to using any single parameter alone. CONCLUSION MR Multitasking simultaneously quantifies whole-brain T1/T2/T1ρ and is clinically promising for quantitative tissue characterization of neurological diseases, such as MS.
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Affiliation(s)
- Sen Ma
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Nan Wang
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Zhaoyang Fan
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Marwa Kaisey
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Nancy L Sicotte
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Anthony G Christodoulou
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
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12
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Guo R, Cai X, Kucukseymen S, Rodriguez J, Paskavitz A, Pierce P, Goddu B, Thompson RB, Nezafat R. Free-breathing simultaneous myocardial T 1 and T 2 mapping with whole left ventricle coverage. Magn Reson Med 2020; 85:1308-1321. [PMID: 33078443 DOI: 10.1002/mrm.28506] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 01/20/2023]
Abstract
PURPOSE To develop a free-breathing sequence, that is, Multislice Joint T1 -T2 , for simultaneous measurement of myocardial T1 and T2 for multiple slices to achieve whole left-ventricular coverage. METHODS Multislice Joint T1 -T2 adopts slice-interleaved acquisition to collect 10 single-shot electrocardiogram-triggered images for each slice prepared by saturation and T2 preparation to simultaneously estimate myocardial T1 and T2 and achieve whole left-ventricular coverage. Prospective slice-tracking using a respiratory navigator and retrospective image registration are used to reduce through-plane and in-plane motion, respectively. Multislice Joint T1 -T2 was validated through numerical simulations and phantom and in vivo experiments, and compared with saturation-recovery single-shot acquisition and T2 -prepared balanced Steady-State Free Precession (T2 -prep SSFP) sequences. RESULTS Phantom T1 and T2 from Multislice Joint T1 -T2 had good accuracy and precision, and were insensitive to heart rate. Multislice Joint T1 -T2 yielded T1 and T2 maps of nine left-ventricular slices in 1.4 minutes. The mean left-ventricular T1 difference between saturation-recovery single-shot acquisition and Multislice Joint T1 -T2 across healthy subjects and patients was 191 ms (1564 ± 60 ms versus 1373 ± 50 ms; P < .05) and 111 ms (1535 ± 49 ms vs 1423 ± 49 ms; P < .05), respectively. The mean difference in left-ventricular T2 between T2 -prep SSFP and Multislice Joint T1 -T2 across healthy subjects and patients was -6.3 ms (42.4 ± 1.4 ms vs 48.7 ± 2.5; P < .05) and -5.7 ms (41.6 ± 2.5 ms vs 47.3 ± 2.7; P < .05), respectively. CONCLUSION Multislice Joint T1 -T2 enables quantification of whole left-ventricular T1 and T2 during free breathing within a clinically feasible scan time of less than 2 minutes.
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Affiliation(s)
- Rui Guo
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Xiaoying Cai
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.,Siemens Medical Solutions USA, Inc., Boston, Massachusetts, USA
| | - Selcuk Kucukseymen
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Jennifer Rodriguez
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Amanda Paskavitz
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Patrick Pierce
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Beth Goddu
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Richard B Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Reza Nezafat
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
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13
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van Houdt PJ, Kallehauge JF, Tanderup K, Nout R, Zaletelj M, Tadic T, van Kesteren ZJ, van den Berg CAT, Georg D, Côté JC, Levesque IR, Swamidas J, Malinen E, Telliskivi S, Brynolfsson P, Mahmood F, van der Heide UA. Phantom-based quality assurance for multicenter quantitative MRI in locally advanced cervical cancer. Radiother Oncol 2020; 153:114-121. [PMID: 32931890 DOI: 10.1016/j.radonc.2020.09.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND AND PURPOSE A wide variation of MRI systems is a challenge in multicenter imaging biomarker studies as it adds variation in quantitative MRI values. The aim of this study was to design and test a quality assurance (QA) framework based on phantom measurements, for the quantitative MRI protocols of a multicenter imaging biomarker trial of locally advanced cervical cancer. MATERIALS AND METHODS Fifteen institutes participated (five 1.5 T and ten 3 T scanners). Each institute optimized protocols for T2, diffusion-weighted imaging, T1, and dynamic contrast-enhanced (DCE-)MRI according to system possibilities, institutional preferences and study-specific constraints. Calibration phantoms with known values were used for validation. Benchmark protocols, similar on all systems, were used to investigate whether differences resulted from variations in institutional protocols or from system variations. Bias, repeatability (%RC), and reproducibility (%RDC) were determined. Ratios were used for T2 and T1 values. RESULTS The institutional protocols showed a range in bias of 0.88-0.98 for T2 (median %RC = 1%; %RDC = 12%), -0.007 to 0.029 × 10-3 mm2/s for the apparent diffusion coefficient (median %RC = 3%; %RDC = 18%), and 0.39-1.29 for T1 (median %RC = 1%; %RDC = 33%). For DCE a nonlinear vendor-specific relation was observed between measured and true concentrations with magnitude data, whereas the relation was linear when phase data was used. CONCLUSION We designed a QA framework for quantitative MRI protocols and demonstrated for a multicenter trial for cervical cancer that measurement of consistent T2 and apparent diffusion coefficient values is feasible despite protocol differences. For DCE-MRI and T1 mapping with the variable flip angle method, this was more challenging.
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Affiliation(s)
- Petra J van Houdt
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, the Netherlands.
| | | | - Kari Tanderup
- Department of Clinical Medicine, Aarhus University Hospital, Denmark
| | - Remi Nout
- Department of Radiation Oncology, Leiden University Medical Center, the Netherlands
| | - Marko Zaletelj
- Department of Radiotherapy, Institute of Oncology Ljubljana, Slovenia
| | - Tony Tadic
- Radiation Medicine Program, Princess Margaret Cancer Center, Toronto, Canada
| | - Zdenko J van Kesteren
- Department of Radiation Oncology, Amsterdam University Medical Center, the Netherlands
| | | | - Dietmar Georg
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University Of Vienna, Austria
| | - Jean-Charles Côté
- Department of Radiation Oncology, Centre Hospitalier de l'Universite de Montreal, Canada
| | - Ives R Levesque
- Medical Physics Unit and Gerald Bronfman Department of Oncology, McGill University, Montreal, Canada
| | - Jamema Swamidas
- Department of Radiation Oncology, Tata Memorial Centre, Mumbai, India
| | - Eirik Malinen
- Department of Medical Physics, Oslo University Hospital, Norway
| | - Sven Telliskivi
- Department of Radiation Oncology, North-Estonia Medical Centre, Tallinn, Estonia
| | - Patrik Brynolfsson
- Department of Translational Sciences, Skåne University Hospital, Lund, Sweden
| | - Faisal Mahmood
- Department of Oncology, Odense University Hospital, Denmark; Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Uulke A van der Heide
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, the Netherlands
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14
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Accelerated T2 Mapping of the Lumbar Intervertebral Disc: Highly Undersampled K-Space Data for Robust T2 Relaxation Time Measurement in Clinically Feasible Acquisition Times. Invest Radiol 2020; 55:695-701. [PMID: 32649331 DOI: 10.1097/rli.0000000000000690] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
T2 mapping of the intervertebral disc (IVD) can depict quantitative changes reflecting biochemical change due to loss of glycosaminoglycan content. Conventional T2 mapping is usually performed using a 2-dimensional multi-echo-spin echo sequence (2D-MESE) with long acquisition times that are generally not compatible with clinical routine. This study investigates the applicability of GRAPPATINI, a T2 mapping sequence combining undersampling, model-based reconstruction, and parallel imaging, to offer clinically feasible acquisition times in T2 mapping of the lumbar IVD. MATERIALS AND METHODS Fifty-eight individuals (26 female; mean age, 23.3 ± 8.1 years) were prospectively studied at 3 T. GRAPPATINI was conducted with the same parameters as the 2D-MESE while shortening the acquisition time from 13:18 to 2:27 minutes. The setup was also validated in a phantom experiment using a 6.48-hour-long single echo-spin echo sequence as reference. The IVDs were manually segmented on 4 central slices. RESULTS The median nucleus pulposus showed a strong Pearson correlation coefficient between T2GRAPPATINI and T2MESE (rp = 0.919; P < 0.001). There was also a significant correlation for the ventral (rp = 0.241; P < 0.001) and posterior (rp = 0.418; P < 0.001) annular regions.In the single spin-echo phantom experiment, the most accurate T2 estimation was achieved using T2GRAPPATINI with a median absolute deviation of 15.3 milliseconds as compared with T2MESE with 26.5 milliseconds. CONCLUSIONS GRAPPATINI facilitates precise T2 mapping at 3 T in accordance with clinical standards and reference methods using the same parameters while shortening acquisition times from 13:18 to 2:27 minutes with the same parameters.
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15
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Bano W, Piredda GF, Davies M, Marshall I, Golbabaee M, Meuli R, Kober T, Thiran JP, Hilbert T. Model-based super-resolution reconstruction of T 2 maps. Magn Reson Med 2019; 83:906-919. [PMID: 31517404 DOI: 10.1002/mrm.27981] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/19/2019] [Accepted: 08/12/2019] [Indexed: 12/14/2022]
Abstract
PURPOSE High-resolution isotropic T2 mapping of the human brain with multi-echo spin-echo (MESE) acquisitions is challenging. When using a 2D sequence, the resolution is limited by the slice thickness. If used as a 3D acquisition, specific absorption rate limits are easily exceeded due to the high power deposition of nonselective refocusing pulses. A method to reconstruct 1-mm3 isotropic T2 maps is proposed based on multiple 2D MESE acquisitions. Data were undersampled (10-fold) to compensate for the prolonged scan time stemming from the super-resolution acquisition. THEORY AND METHODS The proposed method integrates a classical super-resolution with an iterative model-based approach to reconstruct quantitative maps from a set of undersampled low-resolution data. The method was tested on numerical and multipurpose phantoms, and in vivo data. T2 values were assessed with a region-of-interest analysis using a single-slice spin-echo and a fully sampled MESE acquisition in a phantom, and a MESE acquisition in healthy volunteers. RESULTS Numerical simulations showed that the best trade-off between acceleration and number of low-resolution datasets is 10-fold acceleration with 4 acquisitions (acquisition time = 18 min). The proposed approach showed improved resolution over low-resolution images for both phantom and brain. Region-of-interest analysis of the phantom compartments revealed that at shorter T2 , the proposed method was comparable with the fully sampled MESE. For the volunteer data, the T2 values found in the brain structures were consistent across subjects (8.5-13.1 ms standard deviation). CONCLUSION The proposed method addresses the inherent limitations associated with high-resolution T2 mapping and enables the reconstruction of 1 mm3 isotropic relaxation maps with a 10 times faster acquisition.
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Affiliation(s)
- Wajiha Bano
- Institute for Digital Communications, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Gian Franco Piredda
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland.,LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Department of Radiology, University Hospital Lausanne (CHUV), Switzerland
| | - Mike Davies
- Institute for Digital Communications, University of Edinburgh, Edinburgh, United Kingdom
| | - Ian Marshall
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Reto Meuli
- Department of Radiology, University Hospital Lausanne (CHUV), Switzerland
| | - Tobias Kober
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland.,LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Department of Radiology, University Hospital Lausanne (CHUV), Switzerland
| | - Jean-Philippe Thiran
- LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Department of Radiology, University Hospital Lausanne (CHUV), Switzerland
| | - Tom Hilbert
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland.,LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Department of Radiology, University Hospital Lausanne (CHUV), Switzerland
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16
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Michálek J, Hanzlíková P, Trinh T, Pacík D. Fast and accurate compensation of signal offset for T 2 mapping. MAGMA (NEW YORK, N.Y.) 2019; 32:423-436. [PMID: 30730022 DOI: 10.1007/s10334-019-00737-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
OBJECTIVE T2 maps are more vendor independent than other MRI protocols. Multi-echo spin-echo signal decays to a non-zero offset due to imperfect refocusing pulses and Rician noise, causing T2 overestimation by the vendor's 2-parameter algorithm. The accuracy of the T2 estimate is improved, if the non-zero offset is estimated as a third parameter. Three-parameter Levenberg-Marquardt (LM) T2 estimation takes several minutes to calculate, and it is sensitive to initial values. We aimed for a 3-parameter fitting algorithm that was comparably accurate, yet substantially faster. METHODS Our approach gains speed by converting the 3-parameter minimisation problem into an empirically unimodal univariate problem, which is quickly minimised using the golden section line search (GS). RESULTS To enable comparison, we propose a novel noise-masking algorithm. For clinical data, the agreement between the GS and the LM fit is excellent, yet the GS algorithm is two orders of magnitude faster. For synthetic data, the accuracy of the GS algorithm is on par with that of the LM fit, and the GS algorithm is significantly faster. The GS algorithm requires no parametrisation or initialisation by the user. DISCUSSION The new GS T2 mapping algorithm offers a fast and much more accurate off-the-shelf replacement for the inaccurate 2-parameter fit in the vendor's software.
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Affiliation(s)
- Jan Michálek
- Centre for Biomedical Image Analysis, Faculty of Informatics, Masaryk University, Botanická 68a, 602 00, Brno, Czech Republic.
| | - Pavla Hanzlíková
- Department of Radiology, Faculty of Medicine and Dentistry, Palacky University, tř. Svobody 8, 77126, Olomouc, Czech Republic
| | - Tuan Trinh
- Department of Urology, Medical School, Masaryk University, Jihlavská 20, 62500, Brno, Czech Republic
| | - Dalibor Pacík
- Department of Urology, University Hospital Brno, Jihlavská 20, 62500, Brno, Czech Republic
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17
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Hilbert T, Schulz J, Marques JP, Thiran J, Krueger G, Norris DG, Kober T. Fast model‐based T
2
mapping using SAR‐reduced simultaneous multislice excitation. Magn Reson Med 2019; 82:2090-2103. [DOI: 10.1002/mrm.27890] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/23/2019] [Accepted: 06/13/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Tom Hilbert
- Advanced Clinical Imaging Technology Siemens Healthcare Lausanne Switzerland
- Department of Radiology Lausanne University Hospital Lausanne Switzerland
- Signal Processing Laboratory 5 École Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Jenni Schulz
- Donders Institute for Brain, Cognition and Behavior Radboud University Nijmegen Nijmegen Netherlands
| | - José P. Marques
- Donders Institute for Brain, Cognition and Behavior Radboud University Nijmegen Nijmegen Netherlands
| | - Jean‐Philippe Thiran
- Department of Radiology Lausanne University Hospital Lausanne Switzerland
- Signal Processing Laboratory 5 École Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Gunnar Krueger
- Technology and Innovation EMEA, Siemens Healthcare Lausanne Switzerland
| | - David G. Norris
- Donders Institute for Brain, Cognition and Behavior Radboud University Nijmegen Nijmegen Netherlands
| | - Tobias Kober
- Advanced Clinical Imaging Technology Siemens Healthcare Lausanne Switzerland
- Department of Radiology Lausanne University Hospital Lausanne Switzerland
- Signal Processing Laboratory 5 École Polytechnique Fédérale de Lausanne Lausanne Switzerland
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18
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Fishbein KW, Sexton KW, Celik H, Reiter DA, Bouhrara M, Spencer RG. Stabilization of T 2 relaxation and magnetization transfer in cartilage explants by immersion in perfluorocarbon liquid. Magn Reson Med 2019; 81:3209-3217. [PMID: 30667088 DOI: 10.1002/mrm.27650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 12/20/2022]
Abstract
PURPOSE Magnetic resonance imaging of ex vivo cartilage measures parameters such as T2 and magnetization transfer ratio (MTR), which reflect structural changes associated with osteoarthritis. Samples are often immersed in aqueous solutions to prevent dehydration and to to improve susceptibility matching. This study sought to determine the extent to which T2 and MTR changes are attributable to immersion alone and to identify immersion conditions to minimize this confounding factor. METHODS T2 and MTR were measured before and after immersion for up to 24 hours at 4°C. Bovine nasal and articular cartilage and human articular cartilage were studied. Experimental groups included undisturbed immersion in Fluorinert FC-770, a susceptibility-matched, hydrophobic liquid with minimal tissue penetration, and immersion in Fluorinert, Dulbecco's phosphate-buffered saline (DPBS), or saline, with removal from the magnet between scans. 19 F and 1 H-MRI were used to detect cartilage penetration by Fluorinert and swelling, respectively. RESULTS Saline and DPBS immersion rapidly increased T2 , wet weight and cartilage volume and decreased MTR, suggesting increased water content for all cartilage types. Fluorinert-immersed samples exhibited minimal changes in T2 or MTR. No ingress of Fluorinert was detected after 2 weeks of continuous immersion at 4°C. CONCLUSION Ex vivo quantitative MR studies of cartilage may be confounded by the effects of immersion in aqueous solution, which may be comparable to or larger than effects attributed to pathology. These effects may be mitigated by immersion in perfluorocarbon liquids such as Fluorinert FC-770.
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Affiliation(s)
- Kenneth W Fishbein
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Kyle W Sexton
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Hasan Celik
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - David A Reiter
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Mustapha Bouhrara
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Richard G Spencer
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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