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Rivera-Rivera LA, Vikner T, Eisenmenger L, Johnson SC, Johnson KM. Four-dimensional flow MRI for quantitative assessment of cerebrospinal fluid dynamics: Status and opportunities. NMR IN BIOMEDICINE 2024; 37:e5082. [PMID: 38124351 PMCID: PMC11162953 DOI: 10.1002/nbm.5082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 10/03/2023] [Accepted: 11/07/2023] [Indexed: 12/23/2023]
Abstract
Neurological disorders can manifest with altered neurofluid dynamics in different compartments of the central nervous system. These include alterations in cerebral blood flow, cerebrospinal fluid (CSF) flow, and tissue biomechanics. Noninvasive quantitative assessment of neurofluid flow and tissue motion is feasible with phase contrast magnetic resonance imaging (PC MRI). While two-dimensional (2D) PC MRI is routinely utilized in research and clinical settings to assess flow dynamics through a single imaging slice, comprehensive neurofluid dynamic assessment can be limited or impractical. Recently, four-dimensional (4D) flow MRI (or time-resolved three-dimensional PC with three-directional velocity encoding) has emerged as a powerful extension of 2D PC, allowing for large volumetric coverage of fluid velocities at high spatiotemporal resolution within clinically reasonable scan times. Yet, most 4D flow studies have focused on blood flow imaging. Characterizing CSF flow dynamics with 4D flow (i.e., 4D CSF flow) is of high interest to understand normal brain and spine physiology, but also to study neurological disorders such as dysfunctional brain metabolite waste clearance, where CSF dynamics appear to play an important role. However, 4D CSF flow imaging is challenged by the long T1 time of CSF and slower velocities compared with blood flow, which can result in longer scan times from low flip angles and extended motion-sensitive gradients, hindering clinical adoption. In this work, we review the state of 4D CSF flow MRI including challenges, novel solutions from current research and ongoing needs, examples of clinical and research applications, and discuss an outlook on the future of 4D CSF flow.
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Affiliation(s)
- Leonardo A Rivera-Rivera
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Tomas Vikner
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Radiation Sciences, Radiation Physics and Biomedical Engineering, Umeå University, Umeå, Sweden
| | - Laura Eisenmenger
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Sterling C Johnson
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Kevin M Johnson
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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Li Z, Sun A, Liu C, Sun H, Wei H, Wang S, Li R. Technical Note: Swing golden angle - A navigator-interleaved golden angle trajectory with eddy current suppression - Application in free-running cardiac MRI. Med Phys 2024. [PMID: 38837254 DOI: 10.1002/mp.17188] [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: 06/21/2023] [Revised: 02/20/2024] [Accepted: 03/23/2024] [Indexed: 06/07/2024] Open
Abstract
BACKGROUND Golden angle (GA) radial trajectory is advantageous for dynamic magnetic resonance imaging (MRI). Recently, several advanced algorithms have been developed based on navigator-interleaved GA trajectory to realize free-running cardiac MRI. However, navigator-interleaved GA trajectory suffers from the eddy-current effect, which reduces the image quality. PURPOSE This work aims to integrate the navigator-interleaved GA trajectory with clinical cardiac MRI acquisition, with the minimum eddy-current artifacts. The ultimate goal is to realize a high-quality free-running cardiac imaging technique. METHODS In this paper, we propose a new "swing golden angle" (swingGA) radial profile order. SwingGA samples the k-space by rotating back and forth at the generalized golden ratio interval, with smoothly interleaved navigator readouts. The sampling efficiency and angle increment distributions were investigated by numerical simulations. Static phantom imaging experiments were conducted to evaluate the eddy current effect, compared with cartesian, golden angle radial (GA), and tiny golden angle (tGA) trajectories. Furthermore, 12 heart-healthy subjects (aged 21-25 years) were recruited for free-running cardiac imaging with different sampling trajectories. Dynamic images were reconstructed by a low-rank subspace-constrained algorithm. The image quality was evaluated by signal-to-noise-ratio and spectrum analysis in the heart region, and compared with traditional clinical cardiac MRI images. RESULTS SwingGA pattern achieves the highest sampling efficiency (mSE > 0.925) and the minimum azimuthal angle increment (mAD < 1.05). SwingGA can effectively suppress eddy currents in static phantom images, with the lowest normalized root mean square error (nRMSE) values among radial trajectories. For the in-vivo cardiac images, swingGA enjoys the highest SNR both in the blood pool and myocardium, and contains the minimum level of high-frequency artifacts. The free-running cardiac images have good consistency with traditional clinical cardiac MRI, and the swingGA sampling pattern achieves the best image quality among all sampling patterns. CONCLUSIONS The proposed swingGA sampling pattern can effectively improve the sampling efficiency and reduce the eddy currents for the navigator-interleaved GA sequence. SwingGA is a promising sampling pattern for free-running cardiac MRI.
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Affiliation(s)
- Zhongsen Li
- Center for Biomedical Imaging Research, School of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Aiqi Sun
- Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas, USA
| | - Chuyu Liu
- Center for Biomedical Imaging Research, School of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Haozhong Sun
- Center for Biomedical Imaging Research, School of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Haining Wei
- Center for Biomedical Imaging Research, School of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Shuai Wang
- Center for Biomedical Imaging Research, School of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Rui Li
- Center for Biomedical Imaging Research, School of Biomedical Engineering, Tsinghua University, Beijing, China
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Lechuga LM, Cho MM, Vail DM, Captini CM, Fain SB, Begovatz P. Feasibility and optimization of 19F MRI on a clinical 3T with a large field-of-view torso coil. Phys Med Biol 2024; 69:125002. [PMID: 38759675 PMCID: PMC11149172 DOI: 10.1088/1361-6560/ad4d50] [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: 10/21/2023] [Revised: 04/30/2024] [Accepted: 05/17/2024] [Indexed: 05/19/2024]
Abstract
Objective.The objective of this work is to: (1) demonstrate fluorine-19 (19F) MRI on a 3T clinical system with a large field of view (FOV) multi-channel torso coil (2) demonstrate an example parameter selection optimization for a19F agent to maximize the signal-to-noise ratio (SNR)-efficiency for spoiled gradient echo (SPGR), balanced steady-state free precession (bSSFP), and phase-cycled bSSFP (bSSFP-C), and (3) validate detection feasibility inex vivotissues.Approach.Measurements were conducted on a 3.0T Discovery MR750w MRI (GE Healthcare, USA) with an 8-channel1H/19F torso coil (MRI Tools, Germany). Numerical simulations were conducted for perfluoropolyether to determine the theoretical parameters to maximize SNR-efficiency for the sequences. Theoretical parameters were experimentally verified, and the sensitivity of the sequences was compared with a 10 min acquisition time with a 3.125 × 3.125 × 3 mm3in-plane resolution. Feasibility of a bSSFP-C was also demonstrated in phantom andex vivotissues.Main Results. Flip angles (FAs) of 12 and 64° maximized the signal for SPGR and bSSFP, and validation of optimal FA and receiver bandwidth showed close agreement with numerical simulations. Sensitivities of 2.47, 5.81, and 4.44ms-0.5mM-1 and empirical detection limits of 20.3, 1.5, and 6.2 mM were achieved for SPGR, bSSFP, and bSSFP-C, respectively. bSSFP and bSSFP-C achieved 1.8-fold greater sensitivity over SPGR (p< 0.01).Significance.bSSFP-C was able to improve sensitivity relative to simple SPGR and reduce both bSSFP banding effects and imaging time. The sequence was used to demonstrate the feasibility of19F MRI at clinical FOVs and field strengths withinex-vivotissues.
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Affiliation(s)
- Lawrence M Lechuga
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
| | - Monica M Cho
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
| | - David M Vail
- Department of Medical Sciences, University of Wisconsin School of Veterinary Medicine, Madison, WI, United States of America
| | - Christian M Captini
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
- Carbone Cancer Center, University of Wisconsin, Madison, WI, United States of America
- Department of Biomedical Engineering, University of Wisconsin School of Engineering, Madison, WI, United States of America
| | - Sean B Fain
- Department of Radiology, University of Iowa, Iowa City, IA, United States of America
| | - Paul Begovatz
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
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Baadsvik EL, Weiger M, Froidevaux R, Schildknecht CM, Ineichen BV, Pruessmann KP. Myelin bilayer mapping in the human brain in vivo. Magn Reson Med 2024; 91:2332-2344. [PMID: 38171541 DOI: 10.1002/mrm.29998] [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: 09/14/2023] [Revised: 11/27/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024]
Abstract
PURPOSE To quantitatively map the myelin lipid-protein bilayer in the live human brain. METHODS This goal was pursued by integrating a multi-TE acquisition approach targeting ultrashort T2 signals with voxel-wise fitting to a three-component signal model. Imaging was performed at 3 T in two healthy volunteers using high-performance RF and gradient hardware and the HYFI sequence. The design of a suitable imaging protocol faced substantial constraints concerning SNR, imaging volume, scan time, and RF power deposition. Model fitting to data acquired using the proposed protocol was made feasible through simulation-based optimization, and filtering was used to condition noise presentation and overall depiction fidelity. RESULTS A multi-TE protocol (11 TEs of 20-780 μs) for in vivo brain imaging was developed in adherence with applicable safety regulations and practical scan time limits. Data acquired using this protocol produced accurate model fitting results, validating the suitability of the protocol for this purpose. Structured, grainy texture of myelin bilayer maps was observed and determined to be a manifestation of correlated image noise resulting from the employed acquisition strategy. Map quality was significantly improved by filtering to uniformize the k-space noise distribution and simultaneously extending the k-space support. The final myelin bilayer maps provided selective depiction of myelin, reconciling competitive resolution (1.4 mm) with adequate SNR and benign noise texture. CONCLUSION Using the proposed technique, quantitative maps of the myelin bilayer can be obtained in vivo. These maps offer unique information content with potential applications in basic research, diagnosis, disease monitoring, and drug development.
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Affiliation(s)
- Emily Louise Baadsvik
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Markus Weiger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Romain Froidevaux
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | | | - Benjamin Victor Ineichen
- Department of Neuroradiology, Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Center for Reproducible Science, University of Zurich, Zurich, Switzerland
| | - Klaas Paul Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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Kunieda K, Makihara K, Yamada S, Yamaguchi M, Nakamura T, Terada Y. Brain Structures in a Human Embryo Imaged with MR Microscopy. Magn Reson Med Sci 2024:mp.2023-0110. [PMID: 38369336 DOI: 10.2463/mrms.mp.2023-0110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024] Open
Abstract
PURPOSE To delineate brain microstructures in human embryos during the formation of the various major primordia by MR microscopy, with different contrasts appropriate for each target. METHODS We focused mainly on the internal structures in the cerebral cortex and the accessory nerves of the brain. To find appropriate sequence parameters, we measured nuclear magnetic resonance (NMR) parameters and created kernel density plots of T1 and T2 values. We performed T1-weighted gradient echo imaging with parameters similar to those used in the previous studies. We performed T2*-weighted gradient echo imaging to delineate the target structures with the appropriate sequence parameters according to the NMR parameter and flip angle measurements. We also performed high-resolution imaging with both T1- and T2*-weighted sequences. RESULTS T1, T2, and T2* values of the target tissues were positively correlated and shorter than those of the surrounding tissues. In T1-weighted images with a voxel size of (30 µm)3 and (20 µm)3, various organs and tissues and the agarose gel were differentiated as in previous studies, and the structure of approximately 40 µm in size was depicted, but the detailed structures within the cerebral cortex and the accessory nerves were not delineated. In T2*-weighted images with a voxel size of (30 µm)3, the layered structure within the cerebral cortex and the accessory nerves were clearly visualized. Overall, T1-weighted images provided more information than T2*-weighted images, but important internal brain structures of interest were visible only in T2*-weighted images. Therefore, it is essential to perform MR microscopy with different contrasts. CONCLUSION We have visualized brain structures in a human embryo that had not previously been delineated by MR microscopy. We discussed pulse sequences appropriate for the structures of interest. This methodology would provide a way to visualize crucial embryological information about the anatomical structure of human embryos.
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Affiliation(s)
- Kazuki Kunieda
- Institute of Pure and Applied Physics, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kazuyuki Makihara
- Institute of Pure and Applied Physics, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shigehito Yamada
- Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
| | - Masayuki Yamaguchi
- Department of Diagnostic Radiology, National Cancer Center Hospital East, Kashiwa, Chiba, Japan
- Division of Functional Imaging, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, Kashiwa, Chiba, Japan
| | - Takashi Nakamura
- Molecular Characterization Unit, Center for Sustainable Resource Research, RIKEN, Wako, Saitama, Japan
| | - Yasuhiko Terada
- Institute of Pure and Applied Physics, University of Tsukuba, Tsukuba, Ibaraki, Japan
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Edelman RR, Leloudas N, Ankenbrandt WJ, Walker MT, Bobustuc GC, Bailes JE, Pruitt AA, Koktzoglou I. Dark Blood Contrast-Enhanced Brain MRI Using Echo-uT 1 RESS. J Magn Reson Imaging 2023. [PMID: 37950398 DOI: 10.1002/jmri.29124] [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: 09/01/2023] [Revised: 10/24/2023] [Accepted: 10/28/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND The widely used magnetization-prepared rapid gradient-echo (MPRAGE) sequence makes enhancing lesions and blood vessels appear bright after gadolinium administration. However, dark blood imaging using T1-weighted Sampling Perfection with Application optimized Contrast using different flip angle Evolution (T1 SPACE) can be advantageous since it improves the conspicuity of small metastases and leptomeningeal disease. As a potential alternative to T1 SPACE, we evaluated a new dark blood sequence called echo-uT1 RESS (unbalanced T1 Relaxation-Enhanced Steady-State). PURPOSE We compared the performance of echo-uT1 RESS with Dixon fid-uT1 RESS, MPRAGE, and T1 SPACE. STUDY TYPE Retrospective, IRB approved. SUBJECTS/PHANTOM Phantom to assess flow properties of echo-uT1 RESS. Twenty-one patients (14 female, age range 35-82 years) with primary and secondary brain tumors. FIELD STRENGTH/SEQUENCES 3 Tesla/MPRAGE, T1 SPACE, Dixon fid-uT1 RESS, echo-uT1 RESS. ASSESSMENT Flow phantom signal vs. velocity as a function of flip angle and sequence. Qualitative image assessment on 4-point scale. Quantitative evaluation of tumor-to-brain contrast, apparent contrast-to-noise ratio (aCNR), and vessel-to-brain aCNR. STATISTICAL TESTS Friedman and Mann-Whitney U tests. A P value <0.05 was considered statistically significant. RESULTS In the phantom, echo-uT1 RESS showed greater flow-dependent signal loss than fid-uT1 RESS. In patients, blood vessels appeared bright with MPRAGE, gray with fid-uT1 RESS, and dark with T1 SPACE and echo-uT1 RESS. For MPRAGE, Dixon fid-uT1 RESS, echo-uT1 RESS, and T1 SPACE, respective tumor-to-brain contrast values were 0.6 ± 0.3, 1.3 ± 0.5, 1.0 ± 0.4, and 0.6 ± 0.4, while normalized aCNR values were 68.9 ± 50.9, 128.4 ± 59.2, 74.2 ± 42.1, and 99.4 ± 73.9. DATA CONCLUSION Volumetric dark blood contrast-enhanced brain MRI is feasible using echo-uT1 RESS. The dark blood effect was improved vs. fid-uT1 RESS, while both uT1 RESS versions provided better tumor-to-brain contrast than MPRAGE. Whereas T1 SPACE provided better tumor aSNR, echo-uT1 RESS provided better Weber contrast, lesion sharpness and a more consistent dark blood effect. EVIDENCE LEVEL 3 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Robert R Edelman
- Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
- Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Nondas Leloudas
- Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
| | | | - Matthew T Walker
- Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
| | - George C Bobustuc
- Neurology, NorthShore University HealthSystem, Evanston, Illinois, USA
| | - Julian E Bailes
- Neurosurgery, NorthShore University HealthSystem, Evanston, Illinois, USA
| | | | - Ioannis Koktzoglou
- Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
- Radiology, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
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Omoumi P, Mourad C, Ledoux JB, Hilbert T. Morphological assessment of cartilage and osteoarthritis in clinical practice and research: Intermediate-weighted fat-suppressed sequences and beyond. Skeletal Radiol 2023; 52:2185-2198. [PMID: 37154871 PMCID: PMC10509097 DOI: 10.1007/s00256-023-04343-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/28/2023] [Accepted: 04/10/2023] [Indexed: 05/10/2023]
Abstract
Magnetic resonance imaging (MRI) is widely regarded as the primary modality for the morphological assessment of cartilage and all other joint tissues involved in osteoarthritis. 2D fast spin echo fat-suppressed intermediate-weighted (FSE FS IW) sequences with a TE between 30 and 40ms have stood the test of time and are considered the cornerstone of MRI protocols for clinical practice and trials. These sequences offer a good balance between sensitivity and specificity and provide appropriate contrast and signal within the cartilage as well as between cartilage, articular fluid, and subchondral bone. Additionally, FS IW sequences enable the evaluation of menisci, ligaments, synovitis/effusion, and bone marrow edema-like signal changes. This review article provides a rationale for the use of FSE FS IW sequences in the morphological assessment of cartilage and osteoarthritis, along with a brief overview of other clinically available sequences for this indication. Additionally, the article highlights ongoing research efforts aimed at improving FSE FS IW sequences through 3D acquisitions with enhanced resolution, shortened examination times, and exploring the potential benefits of different magnetic field strengths. While most of the literature on cartilage imaging focuses on the knee, the concepts presented here are applicable to all joints. KEY POINTS: 1. MRI is currently considered the modality of reference for a "whole-joint" morphological assessment of osteoarthritis. 2. Fat-suppressed intermediate-weighted sequences remain the keystone of MRI protocols for the assessment of cartilage morphology, as well as other structures involved in osteoarthritis. 3. Trends for further development in the field of cartilage and joint imaging include 3D FSE imaging, faster acquisition including AI-based acceleration, and synthetic imaging providing multi-contrast sequences.
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Affiliation(s)
- Patrick Omoumi
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
| | - Charbel Mourad
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Department of Diagnostic and Interventional Radiology, Hôpital Libanais Geitaoui CHU, Achrafieh, Beyrouth, Lebanon
| | - Jean-Baptiste Ledoux
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Tom Hilbert
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Advanced Clinical Imaging Technology, Siemens Healthineers International AG, Lausanne, Switzerland
- LTS5, École Polytechnique FÉdÉrale de Lausanne (EPFL), Lausanne, Switzerland
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Tönnes C, Licht C, Schad LR, Zöllner FG. VirtMRI: A Tool for Teaching MRI. J Med Syst 2023; 47:110. [PMID: 37878060 PMCID: PMC10600316 DOI: 10.1007/s10916-023-02004-4] [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: 12/15/2022] [Accepted: 10/06/2023] [Indexed: 10/26/2023]
Abstract
Magnetic resonance image formation is not trivial and remains a difficult subject for teaching. Therefore, we saw an urgent need to facilitate teaching by developing a practical and easily accessible MR image generator. Due to the increasing interest in X-nuclei MRI, sodium image generation is also offered. The tool is implemented as a web application that is compatible with all standard desktop browsers and is open source. The user interface focuses on the parameters needed for the creation and display of the resulting images. Available MR sequences range from the standard Spin Echo and Inversion Recovery over steady-state to conventional sodium and more advanced single and triple quantum sequences. Additionally, the user interface has parameters to alter the resolution, the noise, and the k-space sampling. Our software is free to use and specifically suited for teaching purposes.
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Affiliation(s)
- Christian Tönnes
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany.
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany.
| | - Christian Licht
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, 68167, Germany
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Zibetti MVW, De Moura HL, Keerthivasan MB, Regatte RR. Optimizing variable flip angles in magnetization-prepared gradient-echo sequences for efficient 3D-T1ρ mapping. Magn Reson Med 2023; 90:1465-1483. [PMID: 37288538 PMCID: PMC10524308 DOI: 10.1002/mrm.29740] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 04/24/2023] [Accepted: 05/17/2023] [Indexed: 06/09/2023]
Abstract
PURPOSE To optimize the choice of the flip angles of magnetization-prepared gradient-echo sequences for improved accuracy, precision, and speed of 3D-T1ρ mapping. METHODS We propose a new optimization approach for finding variable flip-angle values that improve magnetization-prepared gradient-echo sequences used for 3D-T1ρ mapping. This new approach can improve the accuracy and SNR, while reducing filtering effects. We demonstrate the concept in the three different versions of the magnetization-prepared gradient-echo sequences that are typically used for 3D-T1ρ mapping and evaluate their performance in model agarose phantoms (n = 4) and healthy volunteers (n = 5) for knee joint imaging. We also tested the optimization with sequence parameters targeting faster acquisitions. RESULTS Our results show that optimized variable flip angle can improve the accuracy and the precision of the sequences, seen as a reduction of the mean of normalized absolute difference from about 5%-6% to 3%-4% in model phantoms and from 15%-16% to 11%-13% in the knee joint, and improving SNR from about 12-28 to 22-32 in agarose phantoms and about 7-14 to 13-17 in healthy volunteers. The optimization can also compensate for the loss in quality caused by making the sequence faster. This results in sequence configurations that acquire more data per unit of time with SNR and mean of normalized absolute difference measurements close to its slower versions. CONCLUSION The optimization of the variable flip angle can be used to increase accuracy and precision, and to improve the speed of the typical imaging sequences used for quantitative 3D-T1ρ mapping of the knee joint.
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Affiliation(s)
- Marcelo V W Zibetti
- Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Hector L. De Moura
- Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | | | - Ravinder R. Regatte
- Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
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Nagpal P, Grist TM. MR Angiography: Contrast-Enhanced Acquisition Techniques. Magn Reson Imaging Clin N Am 2023; 31:493-501. [PMID: 37414474 DOI: 10.1016/j.mric.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
Contrast-enhanced MR angiography (CE-MRA) is a frequently used MR imaging technique for evaluating cardiovascular structures. In many ways, it is similar to contrast-enhanced computed tomography (CT) angiography, except a gadolinium-based contrast agent (instead of iodinated contrast) is injected. Although the physiological principles of contrast injection overlap, the technical factors behind enhancement and image acquisition are different. CE-MRA provides an excellent alternative to CT for vascular evaluation and follow-up without requiring nephrotoxic contrast and ionizing radiation. This review describes the physical principles, limitations, and technical applications of CE-MRA techniques.
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Affiliation(s)
- Prashant Nagpal
- Cardiovascular Imaging, Department of Radiology, University of Wisconsin-Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53705, USA.
| | - Thomas M Grist
- Radiology, University of Wisconsin Madison, E3/366 600 Highland Avenue, Madison, WI 53792, USA
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11
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Park J, Jang M, Heier L, Limperopoulos C, Zun Z. Rapid anatomical imaging of the neonatal brain using T 2 -prepared 3D balanced steady-state free precession. Magn Reson Med 2023; 89:1456-1468. [PMID: 36420869 PMCID: PMC10208121 DOI: 10.1002/mrm.29537] [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: 07/13/2022] [Revised: 10/18/2022] [Accepted: 11/03/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To develop a new approach to 3D gradient echo-based anatomical imaging of the neonatal brain with a substantially shorter scan time than standard 3D fast spin echo (FSE) methods, while maintaining a high SNR. METHODS T2 -prepration was employed immediately prior to image acquisition of 3D balanced steady-state free precession (bSSFP) with a single trajectory of center-out k-space view ordering, which requires no magnetization recovery time between imaging segments during the scan. This approach was compared with 3D FSE, 2D single-shot FSE, and product 3D bSSFP imaging in numerical simulations, plus phantom and in vivo experiments. RESULTS T2 -prepared 3D bSSFP generated image contrast of gray matter, white matter, and CSF very similar to that of reference T2 -weighted imaging methods, without major image artifacts. Scan time of T2 -prepared 3D bSSFP was remarkably shorter compared to 3D FSE, whereas SNR was comparable to that of 3D FSE and higher than that of 2D single-shot FSE. Specific absorption rate of T2 -prepared 3D bSSFP remained within the safety limit. Determining an optimal imaging flip angle of T2 -prepared 3D bSSFP was critical to minimizing blurring of images. CONCLUSION T2 -prepared 3D bSSFP offers an alternative method for anatomical imaging of the neonatal brain with dramatically reduced scan time compared to standard 3D FSE and higher SNR than 2D single-shot FSE.
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Affiliation(s)
- Jinho Park
- Department of Cardiology, Yonsei University, Seoul, Korea
| | - MinJung Jang
- Department of Radiology, Weill Cornell Medicine, New York, NY, USA
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Korea
| | - Linda Heier
- Department of Radiology, Weill Cornell Medicine, New York, NY, USA
| | - Catherine Limperopoulos
- Developing Brain Institute, Division of Diagnostic Imaging and Radiology, Children’s National Hospital, Washington, DC, USA
- Division of Fetal and Transitional Medicine, Children’s National Hospital, Washington, DC, USA
- Department of Pediatrics, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA
- Department of Radiology, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA
| | - Zungho Zun
- Department of Radiology, Weill Cornell Medicine, New York, NY, USA
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Wen G, Shim V, Holdsworth SJ, Fernandez J, Qiao M, Kasabov N, Wang A. Machine Learning for Brain MRI Data Harmonisation: A Systematic Review. Bioengineering (Basel) 2023; 10:bioengineering10040397. [PMID: 37106584 PMCID: PMC10135601 DOI: 10.3390/bioengineering10040397] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/16/2023] [Accepted: 03/21/2023] [Indexed: 04/29/2023] Open
Abstract
BACKGROUND Magnetic Resonance Imaging (MRI) data collected from multiple centres can be heterogeneous due to factors such as the scanner used and the site location. To reduce this heterogeneity, the data needs to be harmonised. In recent years, machine learning (ML) has been used to solve different types of problems related to MRI data, showing great promise. OBJECTIVE This study explores how well various ML algorithms perform in harmonising MRI data, both implicitly and explicitly, by summarising the findings in relevant peer-reviewed articles. Furthermore, it provides guidelines for the use of current methods and identifies potential future research directions. METHOD This review covers articles published through PubMed, Web of Science, and IEEE databases through June 2022. Data from studies were analysed based on the criteria of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Quality assessment questions were derived to assess the quality of the included publications. RESULTS a total of 41 articles published between 2015 and 2022 were identified and analysed. In the review, MRI data has been found to be harmonised either in an implicit (n = 21) or an explicit (n = 20) way. Three MRI modalities were identified: structural MRI (n = 28), diffusion MRI (n = 7) and functional MRI (n = 6). CONCLUSION Various ML techniques have been employed to harmonise different types of MRI data. There is currently a lack of consistent evaluation methods and metrics used across studies, and it is recommended that the issue be addressed in future studies. Harmonisation of MRI data using ML shows promises in improving performance for ML downstream tasks, while caution should be exercised when using ML-harmonised data for direct interpretation.
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Affiliation(s)
- Grace Wen
- Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand
| | - Vickie Shim
- Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand
- Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
| | - Samantha Jane Holdsworth
- Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
- Mātai Medical Research Institute, Tairāwhiti-Gisborne 4010, New Zealand
- Department of Anatomy & Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Justin Fernandez
- Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand
| | - Miao Qiao
- Department of Computer Science, University of Auckland, Auckland 1142, New Zealand
| | - Nikola Kasabov
- Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand
- Knowledge Engineering and Discovery Research Institute, Auckland University of Technology, Auckland 1010, New Zealand
- Intelligent Systems Research Centre, Ulster University, Londonderry BT52 1SA, UK
- Institute for Information and Communication Technologies, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Alan Wang
- Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand
- Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
- Department of Anatomy & Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand
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Garetier M, Rousset J, Makki K, Brochard S, Rousseau F, Salem DB, Borotikar B. Assessment and comparison of image quality between two real-time sequences for dynamic MRI of distal joints at 3.0 Tesla. Acta Radiol 2023; 64:1093-1102. [PMID: 35616984 DOI: 10.1177/02841851221101889] [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] [Indexed: 11/15/2022]
Abstract
BACKGROUND Real-time sequences allow functional evaluation of various joint structures during a continuous motion and help understand the pathomechanics of underlying musculoskeletal diseases. PURPOSE To assess and compare the image quality of the two most frequently used real-time sequences for joint dynamic magnetic resonance imaging (MRI), acquired during finger and ankle joint motion. MATERIAL AND METHODS A real-time dynamic acquisition protocol, including radiofrequency (RF)-spoiled and balanced steady-state free precession (bSSFP) sequences, optimized for temporal resolution with similar spatial resolution, was performed using a 3.0-T MRI scanner on 10 fingers and 12 ankles from healthy individuals during active motion. Image quality criteria were evaluated on each time frame and compared between these two sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined and compared from regions of interest placed on cortical bone, tendon, fat, and muscle. Visualization of anatomical structures and overall image quality appreciation were rated by two radiologists using a 0-10 grading scale. RESULTS Mean CNR was significantly higher with bSSFP sequence compared to RF-spoiled sequence. The grading score was in the range of 5-9.3 and was significantly higher with RF-spoiled sequence for bone and joint evaluation and overall image appreciation on the two joints. The standard deviation for SNR, CNR, and grading score during motion was smaller with RF-spoiled sequence for both the joints. The inter-reader reliability was excellent (>0.75) for evaluating anatomical structures in both sequences. CONCLUSION A RF-spoiled real-time sequence is recommended for the in vivo clinical evaluation of distal joints on a 3.0-T MRI scanner.
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Affiliation(s)
- Marc Garetier
- Department of Radiology, Military Teaching Hospital Clermont-Tonnerre, Brest, France
- Department of Radiology, University Hospital Morvan, Brest, France
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France
| | - Jean Rousset
- Department of Radiology, Military Teaching Hospital Clermont-Tonnerre, Brest, France
| | - Karim Makki
- INRIA Fluminance, Rennes, France
- 56498IFPEN, Rueil-Malmaison, France
| | - Sylvain Brochard
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France
- Department of Physical and Medical Rehabilitation, University Hospital Morvan, Brest, France
- Department of Paediatric Physical and Medical Rehabilitation, Fondation Ildys, Brest, France
- University of Western Brittany (UBO), Brest, France
| | - François Rousseau
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France
- 52826IMT Atlantique, UBL, Brest, France
| | - Douraïed Ben Salem
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France
- University of Western Brittany (UBO), Brest, France
- Department of Radiology, University Hospital La Cavale Blanche, Brest, France
| | - Bhushan Borotikar
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France
- Symbiosis Centre for Medical Image Analysis, 29630Symbiosis International University, Pune, India
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Application of deep learning-based super-resolution to T1-weighted postcontrast gradient echo imaging of the chest. LA RADIOLOGIA MEDICA 2023; 128:184-190. [PMID: 36609662 PMCID: PMC9938811 DOI: 10.1007/s11547-022-01587-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 12/30/2022] [Indexed: 01/09/2023]
Abstract
OBJECTIVES A deep learning-based super-resolution for postcontrast volume-interpolated breath-hold examination (VIBE) of the chest was investigated in this study. Aim was to improve image quality, noise, artifacts and diagnostic confidence without change of acquisition parameters. MATERIALS AND METHODS Fifty patients who received VIBE postcontrast imaging of the chest at 1.5 T were included in this retrospective study. After acquisition of the standard VIBE (VIBES), a novel deep learning-based algorithm and a denoising algorithm were applied, resulting in enhanced images (VIBEDL). Two radiologists qualitatively evaluated both datasets independently, rating sharpness of soft tissue, vessels, bronchial structures, lymph nodes, artifacts, cardiac motion artifacts, noise levels and overall diagnostic confidence, using a Likert scale ranging from 1 to 4. In the presence of lung lesions, the largest lesion was rated regarding sharpness and diagnostic confidence using the same Likert scale as mentioned above. Additionally, the largest diameter of the lesion was measured. RESULTS The sharpness of soft tissue, vessels, bronchial structures and lymph nodes as well as the diagnostic confidence, the extent of artifacts, the extent of cardiac motion artifacts and noise levels were rated superior in VIBEDL (all P < 0.001). There was no significant difference in the diameter or the localization of the largest lung lesion in VIBEDL compared to VIBES. Lesion sharpness as well as detectability was rated significantly better by both readers with VIBEDL (both P < 0.001). CONCLUSION The application of a novel deep learning-based super-resolution approach in T1-weighted VIBE postcontrast imaging resulted in an improvement in image quality, noise levels and diagnostic confidence as well as in a shortened acquisition time.
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Application of a Deep Learning Algorithm for Combined Super-Resolution and Partial Fourier Reconstruction Including Time Reduction in T1-Weighted Precontrast and Postcontrast Gradient Echo Imaging of Abdominopelvic MR Imaging. Diagnostics (Basel) 2022; 12:diagnostics12102370. [PMID: 36292057 PMCID: PMC9600324 DOI: 10.3390/diagnostics12102370] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/25/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Purpose: The purpose of this study was to test the technical feasibility and the impact on the image quality of a deep learning-based super-resolution reconstruction algorithm in 1.5 T abdominopelvic MR imaging. Methods: 44 patients who underwent abdominopelvic MRI were retrospectively included, of which 4 had to be subsequently excluded. After the acquisition of the conventional volume interpolated breath-hold examination (VIBEStd), images underwent postprocessing, using a deep learning-based iterative denoising super-resolution reconstruction algorithm for partial Fourier acquisitions (VIBESR). Image analysis of 40 patients with a mean age of 56 years (range 18−84 years) was performed qualitatively by two radiologists independently using a Likert scale ranging from 1 to 5, where 5 was considered the best rating. Results: Image analysis showed an improvement of image quality, noise, sharpness of the organs and lymph nodes, and sharpness of the intestine for pre- and postcontrast images in VIBESR compared to VIBEStd (each p < 0.001). Lesion detectability was better for VIBESR (p < 0.001), while there were no differences concerning the number of lesions. Average acquisition time was 16 s (±1) for the upper abdomen and 15 s (±1) for the pelvis for VIBEStd, and 15 s (±1) for the upper abdomen and 14 s (±1) for the pelvis for VIBESR. Conclusion: This study demonstrated the technical feasibility of a deep learning-based super-resolution algorithm including partial Fourier technique in abdominopelvic MR images and illustrated a significant improvement of image quality, noise, and sharpness while reducing TA.
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DIIK-Net: A Full-resolution Cross-domain Deep Interaction Convolutional Neural Network for MR Image Reconstruction. Neurocomputing 2022. [DOI: 10.1016/j.neucom.2022.09.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Topriceanu CC, Pierce I, Moon JC, Captur G. T 2 and T 2⁎ mapping and weighted imaging in cardiac MRI. Magn Reson Imaging 2022; 93:15-32. [PMID: 35914654 DOI: 10.1016/j.mri.2022.07.012] [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: 03/07/2022] [Revised: 07/20/2022] [Accepted: 07/20/2022] [Indexed: 11/29/2022]
Abstract
Cardiac imaging is progressing from simple imaging of heart structure and function to techniques visualizing and measuring underlying tissue biological changes that can potentially define disease and therapeutic options. These techniques exploit underlying tissue magnetic relaxation times: T1, T2 and T2*. Initial weighting methods showed myocardial heterogeneity, detecting regional disease. Current methods are now fully quantitative generating intuitive color maps that do not only expose regionality, but also diffuse changes - meaning that between-scan comparisons can be made to define disease (compared to normal) and to monitor interval change (compared to old scans). T1 is now familiar and used clinically in multiple scenarios, yet some technical challenges remain. T2 is elevated with increased tissue water - oedema. Should there also be blood troponin elevation, this oedema likely reflects inflammation, a key biological process. T2* falls in the presence of magnetic/paramagnetic materials - practically, this means it measures tissue iron, either after myocardial hemorrhage or in myocardial iron overload. This review discusses how T2 and T2⁎ imaging work (underlying physics, innovations, dependencies, performance), current and emerging use cases, quality assurance processes for global delivery and future research directions.
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Affiliation(s)
- Constantin-Cristian Topriceanu
- Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK; UCL Institute of Cardiovascular Science, University College London, London, UK; UCL MRC Unit for Lifelong Health and Ageing, University College London, London, UK
| | - Iain Pierce
- Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK; UCL Institute of Cardiovascular Science, University College London, London, UK
| | - James C Moon
- Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK; UCL Institute of Cardiovascular Science, University College London, London, UK
| | - Gabriella Captur
- Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK; UCL Institute of Cardiovascular Science, University College London, London, UK; UCL MRC Unit for Lifelong Health and Ageing, University College London, London, UK; The Royal Free Hospital, Centre for Inherited Heart Muscle Conditions, Cardiology Department, Pond Street, Hampstead, London, UK.
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Afat S, Wessling D, Afat C, Nickel D, Arberet S, Herrmann J, Othman AE, Gassenmaier S. Analysis of a Deep Learning-Based Superresolution Algorithm Tailored to Partial Fourier Gradient Echo Sequences of the Abdomen at 1.5 T: Reduction of Breath-Hold Time and Improvement of Image Quality. Invest Radiol 2022; 57:157-162. [PMID: 34510101 DOI: 10.1097/rli.0000000000000825] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The aim of this study was to investigate the feasibility and impact of a novel deep learning superresolution algorithm tailored to partial Fourier allowing retrospectively theoretical acquisition time reduction in 1.5 T T1-weighted gradient echo imaging of the abdomen. MATERIALS AND METHODS Fifty consecutive patients who underwent a 1.5 T contrast-enhanced magnetic resonance imaging examination of the abdomen between April and May 2021 were included in this retrospective study. After acquisition of a conventional T1-weighted volumetric interpolated breath-hold examination using Dixon for water-fat separation (VIBEStd), the acquired data were reprocessed including a superresolution algorithm that was optimized for partial Fourier acquisitions (VIBESR). To accelerate theoretically the acquisition process, a more aggressive partial Fourier setting was applied in VIBESR reconstructions practically corresponding to a shorter acquisition for the data included in the retrospective reconstruction. Precontrast, dynamic contrast-enhanced, and postcontrast data sets were processed. Image analysis was performed by 2 radiologists independently in a blinded random order without access to clinical data regarding the following criteria using a Likert scale ranging from 1 to 4 with 4 being the best: noise levels, sharpness and contrast of vessels, sharpness and contrast of organs and lymph nodes, overall image quality, diagnostic confidence, and lesion conspicuity.Wilcoxon signed rank test for paired data was applied to test for significance. RESULTS Mean patient age was 61 ± 14 years. Mean acquisition time for the conventional VIBEStd sequence was 15 ± 1 seconds versus theoretical 13 ± 1 seconds of acquired data used for the VIBESR reconstruction. Noise levels were evaluated to be better in VIBESR with a median of 4 (4-4) versus a median of 3 (3-3) in VIBEStd by both readers (P < 0.001). Sharpness and contrast of vessels as well as organs and lymph nodes were also evaluated to be superior in VIBESR compared with VIBEStd with a median of 4 (4-4) versus a median of 3 (3-3) (P < 0.001). Diagnostic confidence was also rated superior in VIBESR with a median of 4 (4-4) versus a median of 3.5 (3-4) in VIBEStd by reader 1 and with a median of 4 (4-4) for VIBESR and a median of 4 (4-4) for VIBEStd by reader 2 (both P < 0.001). CONCLUSIONS Image enhancement using deep learning-based superresolution tailored to partial Fourier acquisitions of T1-weighted gradient echo imaging of the abdomen provides improved image quality and diagnostic confidence in combination with more aggressive partial Fourier settings leading to shorter scan time.
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Affiliation(s)
- Saif Afat
- From the Departments of Diagnostic and Interventional Radiology
| | - Daniel Wessling
- From the Departments of Diagnostic and Interventional Radiology
| | - Carmen Afat
- Internal Medicine I, Eberhard Karls University Tuebingen, Tuebingen
| | - Dominik Nickel
- MR Applications Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany
| | - Simon Arberet
- Digital Technology and Innovation, Siemens Healthineers, Princeton, NJ
| | - Judith Herrmann
- From the Departments of Diagnostic and Interventional Radiology
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Zhu D, Qin Q. A revisit of the k-space filtering effects of magnetization-prepared 3D FLASH and balanced SSFP acquisitions: Analytical characterization of the point spread functions. Magn Reson Imaging 2022; 88:76-88. [PMID: 35121068 PMCID: PMC8935658 DOI: 10.1016/j.mri.2022.01.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 01/26/2022] [Indexed: 01/12/2023]
Abstract
PURPOSE 3D FLASH and balanced SSFP (bSSFP) are increasingly used in quantitative MRI after contrast preparation. The acquired k-space data are modulated by T1 relaxation (or additional T2 for bSSFP). Three separate sequence parameters including the number of phase-encoding steps per shot (N), flip angle (FA), and TR have made the transient state of rapid gradient echo (GRE) imaging difficult for analysis and optimization. Here we aim to analytically characterize the k-space filtering effect of magnetization-prepared FLASH and bSSFP with the point spread functions (PSF). METHODS The amplitude effect is characterized with the peak magnitude of the PSF, i.e. PSF(0), which, due to their approaching from transient state to steady-state for the GRE acquisitions, obeys a linear (with a slope and an intercept, not proportional) relationship with the prepared longitudinal magnetization (Mprep). The blurring effect is characterized by the FWHM of the PSF. The magnetization-prepared acquisition-dependent image contrast efficiency is characterized with the relative contrast-to-noise ratio (CNR) per unit time (ruCNR). RESULTS The slope of PSF(0) characterizes the relative contrast between different Mprep levels. The intercept of PSF(0) could lead to quantification bias for magnetization-prepared imaging. FLASH and bSSFP experience very little blurring effect, which is to the contrary of conventional fast spin echo (FSE). Analytical selections of N, FA, and TR are provided to optimize ruCNR for different scenarios. CONCLUSIONS PSFs of the FLASH and bSSFP acquisitions are analytically derived and numerically validated, and compared with the FSE acquisition, thus providing a useful tool for optimizing magnetization-prepared GRE acquisitions.
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Comparison of T2 Quantification Strategies in the Abdominal-Pelvic Region for Clinical Use. Invest Radiol 2022; 57:412-421. [PMID: 34999669 DOI: 10.1097/rli.0000000000000852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The aim of the study was to compare different magnetic resonance imaging (MRI) acquisition strategies appropriate for T2 quantification in the abdominal-pelvic area. The different techniques targeted in the study were chosen according to 2 main considerations: performing T2 measurement in an acceptable time for clinical use and preventing/correcting respiratory motion. MATERIALS AND METHODS Acquisitions were performed at 3 T. To select sequences for in vivo measurements, a phantom experiment was conducted, for which the T2 values obtained with the different techniques of interest were compared with the criterion standard (single-echo SE sequence, multiple acquisitions with varying echo time). Repeatability and temporal reproducibility studies for the different techniques were also conducted on the phantom. Finally, an in vivo study was conducted on 12 volunteers to compare the techniques that offer acceptable acquisition time for clinical use and either address or correct respiratory motion. RESULTS For the phantom study, the DESS and T2-preparation techniques presented the lowest precision (ρ2 = 0.9504 and ρ2 = 0.9849 respectively), and showed a poor repeatability/reproducibility compared with the other techniques. The strategy relying on SE-EPI showed the best precision and accuracy (ρ2 = 0.9994 and Cb = 0.9995). GRAPPATINI exhibited a very good precision (ρ2 = 0.9984). For the technique relying on radial TSE, the precision was not as good as GRAPPATINI (ρ2 = 0.9872). The in vivo study demonstrated good respiratory motion management for all of the selected techniques. It also showed that T2 estimate ranges were different from one method to another. For GRAPPATINI and radial TSE techniques, there were significant differences between all the different types of organs of interest. CONCLUSIONS To perform T2 measurement in the abdominal-pelvic region, one should favor a technique with acceptable acquisition time for clinical use, with proper respiratory motion management, with good repeatability, reproducibility, and precision. In this study, the techniques relying respectively on SE-EPI, radial TSE, and GRAPPATINI appeared as good candidates.
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Keskin K, Yilmaz U, Cukur T. Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:14-26. [PMID: 34351856 DOI: 10.1109/tmi.2021.3102852] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Balanced steady-state free precession (bSSFP) imaging enables high scan efficiency in MRI, but differs from conventional sequences in terms of elevated sensitivity to main field inhomogeneity and nonstandard [Formula: see text]-weighted tissue contrast. To address these limitations, multiple bSSFP images of the same anatomy are commonly acquired with a set of different RF phase-cycling increments. Joint processing of phase-cycled acquisitions serves to mitigate sensitivity to field inhomogeneity. Recently phase-cycled bSSFP acquisitions were also leveraged to estimate relaxation parameters based on explicit signal models. While effective, these model-based methods often involve a large number of acquisitions (N ≈ 10-16), degrading scan efficiency. Here, we propose a new constrained ellipse fitting method (CELF) for parameter estimation with improved efficiency and accuracy in phase-cycled bSSFP MRI. CELF is based on the elliptical signal model framework for complex bSSFP signals; and it introduces geometrical constraints on ellipse properties to improve estimation efficiency, and dictionary-based identification to improve estimation accuracy. CELF generates maps of [Formula: see text], [Formula: see text], off-resonance and on-resonant bSSFP signal by employing a separate [Formula: see text] map to mitigate sensitivity to flip angle variations. Our results indicate that CELF can produce accurate off-resonance and banding-free bSSFP maps with as few as N = 4 acquisitions, while estimation accuracy for relaxation parameters is notably limited by biases from microstructural sensitivity of bSSFP imaging.
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Kwon D, Lee C, Chae Y, Kwon IJ, Kim SM, Lee JH. Clinical validation of the 3-dimensional double-echo steady-state with water excitation sequence of MR neurography for preoperative facial and lingual nerve identification. Imaging Sci Dent 2022; 52:259-266. [PMID: 36238701 PMCID: PMC9530289 DOI: 10.5624/isd.20220035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/11/2022] [Accepted: 04/13/2022] [Indexed: 11/18/2022] Open
Affiliation(s)
- Dohyun Kwon
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea
- Department of Oral and Maxillofacial Surgery, Samsung Medical Center, Seoul, Korea
| | - Chena Lee
- Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea
| | - YeonSu Chae
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea
| | - Ik Jae Kwon
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea
| | - Soung Min Kim
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jong-Ho Lee
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea
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Usefulness of contrast-enhanced 3D MR angiography and contrast-enhanced 3D T1 sequence for detecting intracranial infectious aneurysms in infectious endocarditis. Eur J Radiol 2021; 144:110008. [PMID: 34742109 DOI: 10.1016/j.ejrad.2021.110008] [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: 07/15/2021] [Revised: 09/30/2021] [Accepted: 10/21/2021] [Indexed: 11/23/2022]
Abstract
OBJECTIVES To assess the diagnostic value of contrast-enhanced MRA (CE MRA) and CE 3D-T1 for identifying intracranial infectious aneurysms (IIAs) in infective endocarditis (IE) with digital substraction angiography (DSA) as reference. METHODS Twenty-one IE patients (14 males; mean age: 53 years) with 30 IIAs, diameter ranging 1.5-15 mm (<3mm, n = 14, 46.7%; 3-5 mm, n = 12,40%), underwent CE MRA and CE 3D-T1 at 1.5 T. Two readers evaluated images for aneurysm detection, characterization, quality of visualization. DSA was obtained at a median of 3 days (range 1-15) after MRI. RESULTS The sensitivity, specificity, positive and negative predictive values and accuracy of IIA detection were respectively: 80%, 100%, 100%, 82.3%, 90% for CE MRA and 86.7%, 100%, 100%, 88.2%, 93.3% for CE 3D T1 compared to DSA. No significant difference was observed between CE MRA and CE 3D-T1 for accuracy and quality of visualization. All IIAs of ≥3 mm in diameter (16/30; 53.%) were identified by both sequences, which were also able to detect IIAs ≤ 3 mm (n = 14/30, 46.7%). False negatives were observed with both sequences for 4 IIAs of <2 mm, 3 being compressed by hemorrhagic lesions. Two other IIAs of <2 mm were overlooked by CE MRA. CE 3D-T1 overestimated IIAs luminal diameter by 8% relatively to DSA (P = NS). Intra and inter-observer agreement were good and similar with both methods. CONCLUSION Both CE MRA and CE 3D-T1 have good accuracy compared to DSA detection and characterization of IIAs. CE 3D-T1 also evaluates anatomical relationships of IIAs, which could help DSA location and endovascular treatment.
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Edelman RR, Leloudas N, Pang J, Koktzoglou I. Dark blood cardiovascular magnetic resonance of the heart, great vessels, and lungs using electrocardiographic-gated three-dimensional unbalanced steady-state free precession. J Cardiovasc Magn Reson 2021; 23:127. [PMID: 34724939 PMCID: PMC8559409 DOI: 10.1186/s12968-021-00808-2] [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: 06/21/2021] [Accepted: 08/30/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Recently, we reported a novel neuroimaging technique, unbalanced T1 Relaxation-Enhanced Steady-State (uT1RESS), which uses a tailored 3D unbalanced steady-state free precession (3D uSSFP) acquisition to suppress the blood pool signal while minimizing bulk motion sensitivity. In the present work, we hypothesized that 3D uSSFP might also be useful for dark blood imaging of the chest. To test the feasibility of this approach, we performed a pilot study in healthy subjects and patients undergoing cardiovascular magnetic resonance (CMR). MAIN BODY The study was approved by the hospital institutional review board. Thirty-one adult subjects were imaged at 1.5 T, including 5 healthy adult subjects and 26 patients (44 to 86 years, 10 female) undergoing a clinically indicated CMR. Breath-holding was used in 29 subjects and navigator gating in 2 subjects. For breath-hold acquisitions, the 3D uSSFP pulse sequence used a high sampling bandwidth, asymmetric readout, and single-shot along the phase-encoding direction, while 3 shots were acquired for navigator-gated scans. To minimize signal dephasing from bulk motion, electrocardiographic (ECG) gating was used to synchronize the data acquisition to the diastolic phase of the cardiac cycle. To further reduce motion sensitivity, the moment of the dephasing gradient was set to one-fifth of the moment of the readout gradient. Image quality using 3D uSSFP was good-to-excellent in all subjects. The blood pool signal in the thoracic aorta was uniformly suppressed with sharp delineation of the aortic wall including two cases of ascending aortic aneurysm and two cases of aortic dissection. Compared with variable flip angle 3D turbo spin-echo, 3D uSSFP showed improved aortic wall sharpness. It was also more efficient, permitting the acquisition of 24 slices in each breath-hold versus 16 slices with 3D turbo spin-echo and a single slice with dual inversion 2D turbo spin-echo. In addition, lung and mediastinal lesions appeared highly conspicuous compared with the low blood pool signals within the heart and blood vessels. In two subjects, navigator-gated 3D uSSFP provided excellent delineation of cardiac morphology in double oblique multiplanar reformations. CONCLUSION In this pilot study, we have demonstrated the feasibility of using ECG-gated 3D uSSFP for dark blood imaging of the heart, great vessels, and lungs. Further study will be required to fully optimize the technique and to assess clinical utility.
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Affiliation(s)
- Robert R. Edelman
- Department of Radiology, Northshore University HealthSystem, Evanston, IL USA
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL USA
- Walgreen Building, G534, 2650 Ridge Avenue, Evanston, IL 60201 USA
| | - Nondas Leloudas
- Department of Radiology, Northshore University HealthSystem, Evanston, IL USA
| | - Jianing Pang
- Siemens Medical Solutions USA Inc., Chicago, IL USA
| | - Ioannis Koktzoglou
- Department of Radiology, Northshore University HealthSystem, Evanston, IL USA
- Radiology, Pritzker School of Medicine, University of Chicago, Chicago, IL USA
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Imaging multiple sclerosis pathology at 160 μm isotropic resolution by human whole-brain ex vivo magnetic resonance imaging at 3 T. Sci Rep 2021; 11:15491. [PMID: 34326420 PMCID: PMC8322069 DOI: 10.1038/s41598-021-94891-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 07/13/2021] [Indexed: 11/09/2022] Open
Abstract
Postmortem magnetic resonance imaging (MRI) of the fixed healthy and diseased human brain facilitates spatial resolutions and image quality that is not achievable with in vivo MRI scans. Though challenging-and almost exclusively performed at 7 T field strength-depicting the tissue architecture of the entire brain in fine detail is invaluable since it enables the study of neuroanatomy and uncovers important pathological features in neurological disorders. The objectives of the present work were (1) to develop a 3D isotropic ultra-high-resolution imaging approach for human whole-brain ex vivo acquisitions working on a standard clinical 3 T MRI system; and (2) to explore the sensitivity and specificity of this concept for specific pathoanatomical features of multiple sclerosis. The reconstructed images demonstrate unprecedented resolution and soft tissue contrast of the diseased human brain at 3 T, thus allowing visualization of sub-millimetric lesions in the different cortical layers and in the cerebellar cortex, as well as unique cortical lesion characteristics such as the presence of incomplete/complete iron rims, and patterns of iron accumulation. Further details such as the subpial molecular layer, the line of Gennari, and some intrathalamic nuclei are also well distinguishable.
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Gassenmaier S, Herrmann J, Nickel D, Kannengiesser S, Afat S, Seith F, Hoffmann R, Othman AE. Image Quality Improvement of Dynamic Contrast-Enhanced Gradient Echo Magnetic Resonance Imaging by Iterative Denoising and Edge Enhancement. Invest Radiol 2021; 56:465-470. [PMID: 33645949 DOI: 10.1097/rli.0000000000000761] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES The aim of this study was to investigate the impact of a novel edge enhancement and iterative denoising algorithm in 1.5-T T1-weighted dynamic contrast-enhanced (DCE) gradient echo (GRE) magnetic resonance imaging of the abdomen on image quality, noise levels, diagnostic confidence, and lesion detectability. MATERIALS AND METHODS Fifty patients who underwent a clinically indicated magnetic resonance imaging with DCE imaging of the abdomen between June and August 2020 were included in this retrospective, monocentric, institutional review board-approved study. For DCE imaging, a series of 3 volume interpolated breath-hold examinations (VIBEs) was performed. The raw data of all DCE imaging studies were processed twice, once using standard reconstruction (DCES) and again using an edge enhancement and iterative denoising approach (DCEDE). All imaging studies were randomly reviewed by 2 radiologists independently regarding noise levels, arterial contrast, sharpness of vessels, overall image quality, and diagnostic confidence using a Likert scale ranging from 1 to 4, with 4 being the best. Furthermore, lesion detectability was evaluated using the same ranking system. RESULTS All 50 imaging studies were successfully reconstructed with both methods. Interreader agreement (Cohen κ) was substantial to perfect for both readers. Arterial contrast and sharpness of vessels were rated superior by both readers with a median of 4 in DCEDE versus a median of 3 in DCES (P < 0.001). Furthermore, noise levels as well as overall image quality were rated higher with a median of 4 in DCEDE compared with a median of 3 in DCES (P < 0.001). Lesion detectability was evaluated to be superior in DCEDE with a median of 4 versus DCES with a median of 3 (P < 0.001). Consequently, diagnostic confidence was also rated to be superior in DCEDE with a median of 4 versus DCES with a median of 3 (P < 0.001). CONCLUSIONS Iterative denoising and edge enhancement are feasible in DCE imaging of the abdomen providing superior arterial contrast, noise levels, and overall image quality. Furthermore, lesion detectability and diagnostic confidence were significantly improved using this novel reconstruction method. Further reduction of acquisition time might be possible via reduction of increased noise levels using this presented method.
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Affiliation(s)
- Sebastian Gassenmaier
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Judith Herrmann
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Dominik Nickel
- MR Applications Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany
| | | | - Saif Afat
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Ferdinand Seith
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Rüdiger Hoffmann
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Ahmed E Othman
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
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Gassenmaier S, Afat S, Nickel D, Kannengiesser S, Herrmann J, Hoffmann R, Othman AE. Application of a Novel Iterative Denoising and Image Enhancement Technique in T1-Weighted Precontrast and Postcontrast Gradient Echo Imaging of the Abdomen: Improvement of Image Quality and Diagnostic Confidence. Invest Radiol 2021; 56:328-334. [PMID: 33214390 DOI: 10.1097/rli.0000000000000746] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVES The aim of this study was to investigate the impact of a novel iterative denoising and image enhancement technique in T1-weighted precontrast and postcontrast volume-interpolated breath-hold examination (VIBE) of the abdomen on image quality, noise levels, and diagnostic confidence without change of acquisition parameters. MATERIALS AND METHODS Fifty patients were included in this retrospective, monocentric, institutional review board-approved study after clinically indicated magnetic resonance imaging of the abdomen including T1-weighted precontrast and postcontrast imaging. After acquisition of the standard VIBE (VIBES), images were processed with a novel reconstruction algorithm using the same raw data as for VIBES, resulting in a denoised and enhanced dataset (VIBEDE). Two different radiologists evaluated both datasets in a randomized order regarding sharpness of organs as well as vessels, noise levels, artifacts, overall image quality, and diagnostic confidence using a Likert scale ranging from 1 to 4 with 4 being the best. Furthermore, in the presence of focal liver lesions, the largest lesion was measured in the postcontrast dataset, and lesion detectability was analyzed using a Likert scale (1-4). RESULTS Precontrast and postcontrast sharpness of organs and sharpness of vessels were rated significantly superior by both readers in VIBEDE with a median of 4 (interquartile range, 0) compared with VIBES with a median of 3 (1) (all P's < 0.0001). Precontrast and postcontrast noise levels were also rated superior by both readers in VIBEDE with a median of 4 (0) compared with VIBES with a median of 3 (1) for precontrast and a median of 3 (0) (median of 3 [1] for reader 2) for postcontrast imaging (all P's < 0.0001).Overall image quality was also rated higher with a median of 4 (0) in VIBEDE versus 3 (1) in VIBES (P < 0.0001). Twenty-seven imaging studies contained liver lesions. There was no difference regarding the number and localization between the readers and between VIBES and VIBEDE. Lesion detectability was rated by both readers significantly better in VIBEDE with a median of 4 (0) compared with a median of 4 (1) for reader 1 and a median of 3 (1) for reader 2 (P = 0.001 for reader 1; P < 0.001 for reader 2). Consequently, diagnostic confidence was also significantly superior in VIBEDE versus VIBES with a median of 4 (0) for both (P = 0.001). Interreader agreement resulted in a Cohen κ of 0.76 for precontrast analysis as well as of 0.76 for postcontrast analysis. CONCLUSIONS Application of a novel iterative denoising and image enhancement technique in T1-weighted VIBE precontrast and postcontrast imaging of the abdomen is feasible, providing superior image quality, noise levels, and diagnostic confidence.
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Affiliation(s)
- Sebastian Gassenmaier
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Saif Afat
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Dominik Nickel
- MR Applications Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany
| | | | - Judith Herrmann
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Rüdiger Hoffmann
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
| | - Ahmed E Othman
- From the Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tuebingen, Tuebingen
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Carotid wall imaging with 3D_T2_FFE: sequence parameter optimization and comparison with 3D_T2_SPACE. Sci Rep 2021; 11:2255. [PMID: 33500428 PMCID: PMC7838159 DOI: 10.1038/s41598-021-81309-1] [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: 10/10/2020] [Accepted: 01/04/2021] [Indexed: 12/03/2022] Open
Abstract
Similar to sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE), T2-weighted fast field echo (FFE) also has a black blood effect and a high imaging efficiency. The purpose of this study was to optimize 3D_T2_FFE and compare it with 3D_T2_SPACE for carotid imaging. The scanning parameter of 3D_T2_FFE was optimized for the imaging of the carotid wall. Twenty healthy volunteers and 10 patients with carotid plaque underwent cervical 3D_T2_FFE and 3D_T2_SPACE examinations. The signal-to-noise ratios of the carotid wall (SNRwall) and lumen (SNRlumen), and the contrast-to-noise ratios between the wall and lumen (CNRwall_lumen) were compared. The incidence of the residual flow signal at the carotid bifurcation and the grades of flow voids in the cerebellopontine angle region in the two sequences were also compared. The reproducibility of the two sequences was tested. No significant difference was observed between the two sequences in terms of the SNRwall of healthy individuals and patients (P = 0.132 and 0.102, respectively). The SNRlumen in the 3D_T2_FFE images was lower than that in the 3D_T2_SPACE images. No significant difference was observed between the two sequences in terms of the CNRwall-lumen. The incidence of the residual flow signal at the carotid bifurcation in 3D_T2_FFE was significantly lower than that in 3D_T2_SPACE. The grades of flow suppression in the cerebellopontine angle region in 3D_T2_SPACE was lower than that in 3D_T2_FFE. Both sequences showed excellent inter-and intra-observer reproducibility. Compared to 3D_T2_SPACE, 3D_T2_FFE showed stronger flow suppression while maintaining good imaging quality, which can be used as an alternative tool for carotid imaging.
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Stanton EH, Persson NDÅ, Gomolka RS, Lilius T, Sigurðsson B, Lee H, Xavier ALR, Benveniste H, Nedergaard M, Mori Y. Mapping of CSF transport using high spatiotemporal resolution dynamic contrast-enhanced MRI in mice: Effect of anesthesia. Magn Reson Med 2021; 85:3326-3342. [PMID: 33426699 DOI: 10.1002/mrm.28645] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 12/31/2022]
Abstract
PURPOSE Dynamic contrast-enhanced MRI (DCE-MRI) represents the only available approach for glymphatic cerebrospinal fluid (CSF) flow 3D mapping in the brain of living animals and humans. The purpose of this study was to develop a novel DCE-MRI protocol for mapping of the glymphatic system transport with improved spatiotemporal resolution, and to validate the new protocol by comparing the transport in mice anesthetized with either isoflurane or ketamine/xylazine. METHODS The contrast agent, gadobutrol, was administered into the CSF of the cisterna magna and its transport visualized continuously on a 9.4T preclinical scanner using 3D fast-imaging with a steady-state free-precession sequence (3D-FISP), which has a spatial resolution of 0.001 mm3 and a temporal resolution of 30 s. The MR signals were measured dynamically for 60 min in multiple volumes of interest covering the entire CSF space and brain parenchyma. RESULTS The results confirm earlier findings that glymphatic CSF influx is higher under ketamine/xylazine than with isoflurane anesthesia. This was extended to account for new details about the distinct CSF efflux pathways under the two anesthetic regimens. Dynamic contrast MR shows that CSF clearance occurs mainly along the vagus nerve near the jugular vein under isoflurane and via the olfactory bulb under ketamine/xylazine. CONCLUSION The improved spatial and temporal sampling rates afforded by 3D-FISP shed new light on the pharmacological modulation of CSF efflux paths. The present observations may have the potential to set a new standard for future experimental DCE-MRI studies of the glymphatic system.
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Affiliation(s)
- Evan Hunter Stanton
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niklas Daniel Åke Persson
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ryszard Stefan Gomolka
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tuomas Lilius
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Björn Sigurðsson
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hedok Lee
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Anna Lenice Ribeiro Xavier
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Yuki Mori
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Machado-Rivas F, Jaimes C, Kirsch JE, Gee MS. Image-quality optimization and artifact reduction in fetal magnetic resonance imaging. Pediatr Radiol 2020; 50:1830-1838. [PMID: 33252752 DOI: 10.1007/s00247-020-04672-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/09/2020] [Accepted: 03/31/2020] [Indexed: 11/28/2022]
Abstract
Fetal MRI allows for earlier and better detection of complex congenital anomalies. However, its diagnostic utility is often limited by technical barriers that introduce artifacts and reduce image quality. The main determinants of fetal MR image quality are speed of acquisition, spatial resolution and signal-to-noise ratio (SNR). Imaging optimization is a challenge because a change to improve one scan parameter often leads to worsening of another. Moreover, the recent introduction of fetal MRI on 3-tesla (T) scanners to achieve better SNR can amplify some technical issues. Motion, banding artifacts and aliasing artifacts impact the quality of fetal acquisitions at any field strength. High specific absorption rate (SAR) and artifacts from inhomogeneities in the radiofrequency field are important limitations of high-field-strength imaging. We discuss technical barriers that impact image quality and are important limitations to prenatal MRI diagnosis, and propose solutions to improve image quality and reduce artifacts.
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Affiliation(s)
- Fedel Machado-Rivas
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Camilo Jaimes
- Department of Radiology, Harvard Medical School, Boston, MA, USA.,Department of Radiology, Boston Children's Hospital, Boston, MA, USA
| | - John E Kirsch
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Michael S Gee
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA. .,Department of Radiology, Harvard Medical School, Boston, MA, USA.
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31
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IKWI-net: A cross-domain convolutional neural network for undersampled magnetic resonance image reconstruction. Magn Reson Imaging 2020; 73:1-10. [DOI: 10.1016/j.mri.2020.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 06/08/2020] [Accepted: 06/24/2020] [Indexed: 12/16/2022]
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32
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Roberts TA, van Amerom JFP, Uus A, Lloyd DFA, van Poppel MPM, Price AN, Tournier JD, Mohanadass CA, Jackson LH, Malik SJ, Pushparajah K, Rutherford MA, Razavi R, Deprez M, Hajnal JV. Fetal whole heart blood flow imaging using 4D cine MRI. Nat Commun 2020; 11:4992. [PMID: 33020487 PMCID: PMC7536221 DOI: 10.1038/s41467-020-18790-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 09/10/2020] [Indexed: 12/26/2022] Open
Abstract
Prenatal detection of congenital heart disease facilitates the opportunity for potentially life-saving care immediately after the baby is born. Echocardiography is routinely used for screening of morphological malformations, but functional measurements of blood flow are scarcely used in fetal echocardiography due to technical assumptions and issues of reliability. Magnetic resonance imaging (MRI) is readily used for quantification of abnormal blood flow in adult hearts, however, existing in utero approaches are compromised by spontaneous fetal motion. Here, we present and validate a novel method of MRI velocity-encoding combined with a motion-robust reconstruction framework for four-dimensional visualization and quantification of blood flow in the human fetal heart and major vessels. We demonstrate simultaneous 4D visualization of the anatomy and circulation, which we use to quantify flow rates through various major vessels. The framework introduced here could enable new clinical opportunities for assessment of the fetal cardiovascular system in both health and disease.
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Affiliation(s)
- Thomas A Roberts
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK.
| | - Joshua F P van Amerom
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Alena Uus
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - David F A Lloyd
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
- Department of Congenital Heart Disease, Evelina Children's Hospital, London, SE1 7EH, UK
| | - Milou P M van Poppel
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
- Department of Congenital Heart Disease, Evelina Children's Hospital, London, SE1 7EH, UK
| | - Anthony N Price
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Jacques-Donald Tournier
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Chloe A Mohanadass
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Laurence H Jackson
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Shaihan J Malik
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Kuberan Pushparajah
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
- Department of Congenital Heart Disease, Evelina Children's Hospital, London, SE1 7EH, UK
| | - Mary A Rutherford
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
- Centre for the Developing Brain, King's College London, London, SE1 7EH, UK
| | - Reza Razavi
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
- Department of Congenital Heart Disease, Evelina Children's Hospital, London, SE1 7EH, UK
| | - Maria Deprez
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Joseph V Hajnal
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE1 7EH, UK
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Edelman R, Leloudas N, Pang J, Bailes J, Merrell R, Koktzoglou I. Twofold improved tumor-to-brain contrast using a novel T1 relaxation-enhanced steady-state (T 1RESS) MRI technique. SCIENCE ADVANCES 2020; 6:6/44/eabd1635. [PMID: 33115747 PMCID: PMC7608787 DOI: 10.1126/sciadv.abd1635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/15/2020] [Indexed: 06/11/2023]
Abstract
A technique that provides more accurate cancer detection would be of great value. Toward this end, we developed T1 relaxation-enhanced steady-state (T1RESS), a novel magnetic resonance imaging (MRI) pulse sequence that enables the flexible modulation of T1 weighting and provides the unique feature that intravascular signals can be toggled on and off in contrast-enhanced scans. T1RESS makes it possible to effectively use an MRI technique with improved signal-to-noise ratio efficiency for cancer imaging. In a proof-of-concept study, "dark blood" unbalanced T1RESS provided a twofold improvement in tumor-to-brain contrast compared with standard techniques, whereas balanced T1RESS greatly enhanced vascular detail. In conclusion, T1RESS represents a new MRI technique with substantial potential value for cancer imaging, along with a broad range of other clinical applications.
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Affiliation(s)
- R Edelman
- Radiology, NorthShore University HealthSystem, 2650 Ridge Ave., Evanston, IL 60201, USA.
- Northwestern Medicine, 251 E. Huron St., Chicago, IL 60611, USA
| | - N Leloudas
- Radiology, NorthShore University HealthSystem, 2650 Ridge Ave., Evanston, IL 60201, USA
| | - J Pang
- Siemens Medical Solutions USA Inc., 737 N. Michigan Ave., Chicago, IL 60611, USA
| | - J Bailes
- University of Chicago Pritzker School of Medicine, 924 E. 57th St., Chicago, IL 60637, USA
- Neurosurgery, NorthShore University HealthSystem, 2650 Ridge Ave., Evanston, IL 60201, USA
| | - R Merrell
- University of Chicago Pritzker School of Medicine, 924 E. 57th St., Chicago, IL 60637, USA
- Neurology, NorthShore University HealthSystem, 2650 Ridge Ave., Evanston, IL 60201, USA
| | - I Koktzoglou
- Radiology, NorthShore University HealthSystem, 2650 Ridge Ave., Evanston, IL 60201, USA
- University of Chicago Pritzker School of Medicine, 924 E. 57th St., Chicago, IL 60637, USA
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Isaacs BR, Keuken MC, Alkemade A, Temel Y, Bazin PL, Forstmann BU. Methodological Considerations for Neuroimaging in Deep Brain Stimulation of the Subthalamic Nucleus in Parkinson's Disease Patients. J Clin Med 2020; 9:E3124. [PMID: 32992558 PMCID: PMC7600568 DOI: 10.3390/jcm9103124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/17/2020] [Accepted: 09/25/2020] [Indexed: 12/17/2022] Open
Abstract
Deep brain stimulation (DBS) of the subthalamic nucleus is a neurosurgical intervention for Parkinson's disease patients who no longer appropriately respond to drug treatments. A small fraction of patients will fail to respond to DBS, develop psychiatric and cognitive side-effects, or incur surgery-related complications such as infections and hemorrhagic events. In these cases, DBS may require recalibration, reimplantation, or removal. These negative responses to treatment can partly be attributed to suboptimal pre-operative planning procedures via direct targeting through low-field and low-resolution magnetic resonance imaging (MRI). One solution for increasing the success and efficacy of DBS is to optimize preoperative planning procedures via sophisticated neuroimaging techniques such as high-resolution MRI and higher field strengths to improve visualization of DBS targets and vasculature. We discuss targeting approaches, MRI acquisition, parameters, and post-acquisition analyses. Additionally, we highlight a number of approaches including the use of ultra-high field (UHF) MRI to overcome limitations of standard settings. There is a trade-off between spatial resolution, motion artifacts, and acquisition time, which could potentially be dissolved through the use of UHF-MRI. Image registration, correction, and post-processing techniques may require combined expertise of traditional radiologists, clinicians, and fundamental researchers. The optimization of pre-operative planning with MRI can therefore be best achieved through direct collaboration between researchers and clinicians.
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Affiliation(s)
- Bethany R. Isaacs
- Integrative Model-based Cognitive Neuroscience Research Unit, University of Amsterdam, 1018 WS Amsterdam, The Netherlands; (A.A.); (P.-L.B.); (B.U.F.)
- Department of Experimental Neurosurgery, Maastricht University Medical Center, 6202 AZ Maastricht, The Netherlands;
| | - Max C. Keuken
- Municipality of Amsterdam, Services & Data, Cluster Social, 1000 AE Amsterdam, The Netherlands;
| | - Anneke Alkemade
- Integrative Model-based Cognitive Neuroscience Research Unit, University of Amsterdam, 1018 WS Amsterdam, The Netherlands; (A.A.); (P.-L.B.); (B.U.F.)
| | - Yasin Temel
- Department of Experimental Neurosurgery, Maastricht University Medical Center, 6202 AZ Maastricht, The Netherlands;
| | - Pierre-Louis Bazin
- Integrative Model-based Cognitive Neuroscience Research Unit, University of Amsterdam, 1018 WS Amsterdam, The Netherlands; (A.A.); (P.-L.B.); (B.U.F.)
- Max Planck Institute for Human Cognitive and Brain Sciences, D-04103 Leipzig, Germany
| | - Birte U. Forstmann
- Integrative Model-based Cognitive Neuroscience Research Unit, University of Amsterdam, 1018 WS Amsterdam, The Netherlands; (A.A.); (P.-L.B.); (B.U.F.)
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Abdulla SU, Reutens D, Bollmann S, Vegh V. MRI phase offset correction method impacts quantitative susceptibility mapping. Magn Reson Imaging 2020; 74:139-151. [PMID: 32890674 DOI: 10.1016/j.mri.2020.08.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/20/2020] [Accepted: 08/20/2020] [Indexed: 01/05/2023]
Abstract
Individual channel ultra-high field (7T) phase images have to be phase offset corrected prior to the mapping of magnetic susceptibility of tissue. Whilst numerous methods have been proposed for gradient recalled echo MRI phase offset correction, it remains unclear how they affect quantitative magnetic susceptibility values derived from phase images. Methods already proposed either employ a single or multiple echo time MRI data. In terms of the latter, offsets can be derived using an ultra-short echo time acquisition, or by estimating the offset based on two echo points with the assumption of linear phase evolution with echo time. Our evaluation involved 32 channel multi-echo time 7T GRE (Gradient Recalled Echo) and ultra-short echo time PETRA (Pointwise Encoding Time Reduction with Radial Acquisition) MRI data collected for a susceptibility phantom and three human brains. The combined phase images generated using four established offset correction methods (two single and two multiple echo time) were analysed, followed by an assessment of quantitative susceptibility values obtained for a phantom and human brains. The effectiveness of each method in removing the offsets was shown to reduce with increased echo time, decreased signal intensity and reduced overlap in coil sensitivity profiles. Quantitative susceptibility values and how they change with echo time were found to be method specific. Phase offset correction methods based on single echo time data have a tendency to produce more accurate and less noisy quantitative susceptibility maps in comparison with methods employing multiple echo time data.
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Affiliation(s)
| | - David Reutens
- Centre for Advanced Imaging, University of Queensland, Brisbane, Australia
| | - Steffen Bollmann
- Centre for Advanced Imaging, University of Queensland, Brisbane, Australia
| | - Viktor Vegh
- Centre for Advanced Imaging, University of Queensland, Brisbane, Australia.
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36
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Garetier M, Borotikar B, Makki K, Brochard S, Rousseau F, Ben Salem D. Dynamic MRI for articulating joint evaluation on 1.5 T and 3.0 T scanners: setup, protocols, and real-time sequences. Insights Imaging 2020; 11:66. [PMID: 32430739 PMCID: PMC7237553 DOI: 10.1186/s13244-020-00868-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 04/02/2020] [Indexed: 01/31/2023] Open
Abstract
Dynamic magnetic resonance imaging (MRI) is a non-invasive method that can be used to increase the understanding of the pathomechanics of joints. Various types of real-time gradient echo sequences used for dynamic MRI acquisition of joints include balanced steady-state free precession sequence, radiofrequency-spoiled sequence, and ultra-fast gradient echo sequence. Due to their short repetition time and echo time, these sequences provide high temporal resolution, a good signal-to-noise ratio and spatial resolution, and soft tissue contrast. The prerequisites of the evaluation of joints with dynamic MRI include suitable patient installation and optimal positioning of the joint in the coil to allow joint movement, sometimes with dedicated coil support. There are currently few recommendations in the literature regarding appropriate protocol, sequence standardizations, and diagnostic criteria for the use of real-time dynamic MRI to evaluate joints. This article summarizes the technical parameters of these sequences from various manufacturers on 1.5 T and 3.0 T MRI scanners. We have reviewed pertinent details of the patient and coil positioning for dynamic MRI of various joints. The indications and limitations of dynamic MRI of joints are discussed.
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Affiliation(s)
- Marc Garetier
- Department of Radiology, Military Teaching Hospital Clermont-Tonnerre, Rue du colonel Fonferrier, 29240, Brest, Cedex 9, France. .,Department of Radiology, University Hospital Morvan, Brest, France. .,Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France.
| | - Bhushan Borotikar
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France.,University of Western Brittany (UBO), Brest, France.,University Hospital, Brest, France
| | - Karim Makki
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France.,IMT Atlantique, UBL, Brest, France
| | - Sylvain Brochard
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France.,University of Western Brittany (UBO), Brest, France.,Department of Physical and Medical Rehabilitation, University Hospital Morvan, Brest, France.,Department of Paediatric Physical and Medical Rehabilitation, Fondation Ildys, Brest, France
| | - François Rousseau
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France.,IMT Atlantique, UBL, Brest, France
| | - Douraïed Ben Salem
- Laboratory of Medical Information Processing (LATIM), INSERM-UMR 1101, Brest, France.,University of Western Brittany (UBO), Brest, France.,Department of Radiology, University Hospital La Cavale Blanche, Brest, France
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37
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Wyatt CR, Barbara TM, Guimaraes AR. T 1ρ magnetic resonance fingerprinting. NMR IN BIOMEDICINE 2020; 33:e4284. [PMID: 32125050 PMCID: PMC8818303 DOI: 10.1002/nbm.4284] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/03/2020] [Accepted: 02/05/2020] [Indexed: 05/15/2023]
Abstract
T1ρ relaxation imaging is a quantitative imaging technique that has been used to assess cartilage integrity, liver fibrosis, tumors, cardiac infarction, and Alzheimer's disease. T1 , T2 , and T1ρ relaxation time constants have each demonstrated different degrees of sensitivity to several markers of fibrosis and inflammation, allowing for a potential multi-parametric approach to tissue quantification. Traditional magnetic resonance fingerprinting (MRF) has been shown to provide quick, quantitative mapping of T1 and T2 relaxation time constants. In this study, T1ρ relaxation is added to the MRF framework using spin lock preparations. An MRF sequence involving an RF-spoiled sequence with TR , flip angle, T1ρ , and T2 preparation variation is described. The sequence is then calibrated against conventional T1 , T2 , and T1ρ relaxation mapping techniques in agar phantoms and the abdomens of four healthy volunteers. Strong intraclass correlation coefficients (ICC > 0.9) were found between conventional and MRF sequences in phantoms and also in healthy volunteers (ICC > 0.8). The highest ICC correlation values were seen in T1 , followed by T1ρ and then T2 . In this study, T1ρ relaxation has been incorporated into the MRF framework by using spin lock preparations, while still fitting for T1 and T2 relaxation time constants. The acquisition of these parameters within a single breath hold in the abdomen alleviates the issues of movement between breath holds in conventional techniques.
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Affiliation(s)
- Cory R. Wyatt
- Advanced Imaging Research Center, Oregon Health & Sciences University, Portland, OR 97239
- Department of Diagnostic Radiology, Oregon Health & Sciences University, Portland, OR 97239
| | - Thomas M. Barbara
- Advanced Imaging Research Center, Oregon Health & Sciences University, Portland, OR 97239
| | - Alexander R. Guimaraes
- Advanced Imaging Research Center, Oregon Health & Sciences University, Portland, OR 97239
- Department of Diagnostic Radiology, Oregon Health & Sciences University, Portland, OR 97239
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38
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Weiger M, Froidevaux R, Baadsvik EL, Brunner DO, Rösler MB, Pruessmann KP. Advances in MRI of the myelin bilayer. Neuroimage 2020; 217:116888. [PMID: 32360688 DOI: 10.1016/j.neuroimage.2020.116888] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/26/2020] [Accepted: 04/26/2020] [Indexed: 12/19/2022] Open
Abstract
Myelin plays a key role in the function of the central nervous system and is involved in many neurodegenerative diseases. Hence, depiction of myelin is desired for both research and diagnosis. However, MRI of the lipid bilayer constituting the myelin membrane is hampered by extremely rapid signal decay and cannot be accomplished with conventional sequences. Dedicated short-T2 techniques have therefore been employed, yet with extended sequence timings not well matched to the rapid transverse relaxation in the bilayer, which leads to signal loss and blurring. In the present work, capture and encoding of the ultra-short-T2 signals in the myelin bilayer is considerably improved by employing advanced short-T2 methodology and hardware, in particular a high-performance human-sized gradient insert. The approach is applied to tissue samples excised from porcine brain and in vivo in a human volunteer. It is found that the rapidly decaying non-aqueous components in the brain can indeed be depicted with MRI at useful resolution. As a considerable fraction of these signals is related to the myelin bilayer, the presented approach has strong potential to contribute to myelin research and diagnosis.
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Affiliation(s)
- Markus Weiger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.
| | - Romain Froidevaux
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Emily Louise Baadsvik
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - David Otto Brunner
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Manuela Barbara Rösler
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Klaas Paul Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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Froidevaux R, Weiger M, Rösler MB, Brunner DO, Dietrich BE, Reber J, Pruessmann KP. High-resolution short-T 2 MRI using a high-performance gradient. Magn Reson Med 2020; 84:1933-1946. [PMID: 32176828 DOI: 10.1002/mrm.28254] [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: 11/28/2019] [Revised: 02/20/2020] [Accepted: 02/20/2020] [Indexed: 12/17/2022]
Abstract
PURPOSE To achieve high resolution in imaging of short-T2 materials and tissues by using a high-performance human-sized gradient insert with strength up to 200 mT/m and 100% duty cycle. METHODS Dedicated short-T2 methodology and hardware are used, such as the pointwise encoding time reduction with radial acquisition (PETRA) technique with modulated excitation pulses, optimized radio-frequency hardware, and a high-performance gradient insert. A theoretical analysis of actual spatial resolution and SNR is provided to support the choice of scan parameters and interpretation of the results. Imaging is performed in resolution phantoms, animal specimen, and human volunteers at both conventional and maximum available gradient strengths and compared using image subtraction. RESULTS Calculations suggest that increasing gradient strength beyond conventional values considerably improves both actual resolution and SNR efficiency in short-T2 imaging. Resolution improvements are confirmed in all investigated samples, in particular 2 mm slots were resolved in a hard-plastic plate with T2 ≈ 10 μs and in vivo musculoskeletal images were acquired at isotropic 200 μm resolution. Expected improvements in signal yield are realized in fine structures benefitting from high resolution but to less extent in regions of low contrast where decay-related blurring leads to signal overlap between neighboring locations. CONCLUSION Strong gradients with high duty cycle enable short-T2 imaging at unprecedentedly high resolution, holding the potential for improving MRI of, eg, bone, tendon, lung, or teeth. Moreover, it allows direct access of tissues with T2 of tens of microseconds such as myelin or collagen.
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Affiliation(s)
- Romain Froidevaux
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Markus Weiger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Manuela B Rösler
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - David O Brunner
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Benjamin E Dietrich
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Jonas Reber
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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40
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Ludwig DR, Shetty AS, Broncano J, Bhalla S, Raptis CA. Magnetic Resonance Angiography of the Thoracic Vasculature: Technique and Applications. J Magn Reson Imaging 2020; 52:325-347. [PMID: 32061029 DOI: 10.1002/jmri.27067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/05/2020] [Accepted: 01/07/2020] [Indexed: 12/12/2022] Open
Abstract
Magnetic resonance angiography (MRA) is a powerful clinical tool for evaluation of the thoracic vasculature. MRA can be performed on nearly any magnetic resonance imaging (MRI) scanner, and provides images of high diagnostic quality without the use of ionizing radiation. While computed tomographic angiography (CTA) is preferred in the evaluation of hemodynamically unstable patients, MRA represents an important tool for evaluation of the thoracic vasculature in stable patients. Contrast-enhanced MRA is generally performed unless there is a specific contraindication, as it shortens the duration of the exam and provides images of higher diagnostic quality than noncontrast MRA. However, intravenous contrast is often not required to obtain a diagnostic evaluation for most clinical indications. Indeed, a variety of noncontrast MRA techniques are used for thoracic imaging, often in conjunction with contrast-enhanced MRA, each of which has a differing degree of reliance on flowing blood to produce the desired vascular signal. In this article we review contrast-enhanced MRA, with a focus on contrast agents, methods of bolus timing, and considerations in imaging acquisition. Next, we cover the mechanism of contrast, strengths, and weaknesses of various noncontrast MRA techniques. Finally, we present an approach to protocol development and review representative protocols used at our institution for a variety of thoracic applications. Further attention will be devoted to additional techniques employed to address specific clinical questions, such as delayed contrast-enhanced imaging, provocative maneuvers, electrocardiogram and respiratory gating, and phase-contrast imaging. The purpose of this article is to review basic techniques and methodology in thoracic MRA, discuss an approach to protocol development, and illustrate commonly encountered pathology on thoracic MRA examinations. Level of Evidence 5 Technical Efficacy Stage 3.
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Affiliation(s)
- Daniel R Ludwig
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Anup S Shetty
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jordi Broncano
- Cardiothoracic Imaging Section, Health Time, Hospital de la Cruz Roja and San Juan de Dios, Cordoba, Spain
| | - Sanjeev Bhalla
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Constantine A Raptis
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA
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41
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Agarwal S, Sair HI, Gujar S, Pillai JJ. Language Mapping With fMRI: Current Standards and Reproducibility. Top Magn Reson Imaging 2019; 28:225-233. [PMID: 31385902 DOI: 10.1097/rmr.0000000000000216] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Clinical use of blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a relatively new phenomenon, with only about 3 decades of collective experience. Nevertheless, task-based BOLD fMRI has been widely accepted for presurgical planning, over traditional methods, which are invasive and at times perilous. Many studies have demonstrated the ability of BOLD fMRI to make substantial clinical impact with respect to surgical planning and preoperative risk assessment, especially to localize the eloquent motor and visual areas. Reproducibility and repeatability of language fMRI are important in the assessment of its clinical usefulness. There are national efforts currently underway to standardize language fMRI. The American Society of Functional Neuroradiology (ASFNR) has recently provided guidelines on fMRI paradigm algorithms for presurgical language assessment for language lateralization and localization. In this review article, we provide a comprehensive overview of current standards of language fMRI mapping and its reproducibility.
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Affiliation(s)
- Shruti Agarwal
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Haris I Sair
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Sachin Gujar
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jay J Pillai
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD
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Bär S, Oerther T, Weigel M, Müller A, Hucker P, Korvink JG, Ko CW, Wapler MC, Leupold J. On the application of balanced steady-state free precession to MR microscopy. MAGMA (NEW YORK, N.Y.) 2019; 32:437-447. [PMID: 30649708 DOI: 10.1007/s10334-019-00736-4] [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: 09/05/2018] [Revised: 11/30/2018] [Accepted: 01/03/2019] [Indexed: 06/09/2023]
Abstract
OBJECTIVE The applicability of the balanced steady-state free precession (bSSFP) sequence to the field of MR microscopy was investigated, since the potentially high SNR makes bSSFP attractive. However, particularly at ultra-high magnetic fields, a number of constraints emerge: the frequency sensitivity of the bSSFP signal, the duty cycle of the imaging gradients, and the intrinsic diffusion attenuation of the steady state due to the imaging gradients. MATERIALS AND METHODS Optimization of the bSSFP sequence was performed on three imaging systems (7 T and 9.4 T) suited for MR microscopy. Since biological samples are often imaged in the very proximity of materials from sample containers/holder or devices such as electrodes, several microscopy phantoms representing such circumstances were fabricated and examined with 3D bSSFP. RESULTS Artifact-free microscopic bSSFP images could be obtained with voxel sizes down to 16 µm × 16 µm × 78 µm and with an SNR gain of 25% over standard gradient echo images. CONCLUSION With appropriate choice of phantom materials, optimization of the flip angle to the diffusion-attenuated steady state and protocols considering duty-cycle limitations, bSSFP can be a valuable tool in MR microscopy.
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Affiliation(s)
- Sébastien Bär
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center - University of Freiburg, Killianstrasse 5a, 79106, Freiburg, Germany.
- BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Freiburg, Germany.
- Department of Computer Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan.
| | - Thomas Oerther
- Microimaging Applications, Bruker BioSpin GmbH, Rheinstetten, Germany
| | - Matthias Weigel
- Department of Radiology, Division of Radiological Physics, University Hospital Basel, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Angelina Müller
- Department for Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - Patrick Hucker
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center - University of Freiburg, Killianstrasse 5a, 79106, Freiburg, Germany
| | - Jan G Korvink
- Institute of Microstructure Technology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Cheng-Wen Ko
- Department of Computer Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Matthias C Wapler
- Department for Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - Jochen Leupold
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center - University of Freiburg, Killianstrasse 5a, 79106, Freiburg, Germany
- BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Freiburg, Germany
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Liu TT. MRI in systems medicine. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2019; 12:e1463. [PMID: 31365953 DOI: 10.1002/wsbm.1463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/05/2019] [Accepted: 07/05/2019] [Indexed: 11/07/2022]
Abstract
Magnetic resonance imaging (MRI) is one of the primary medical imaging modalities and a key component of the standard of care in modern healthcare systems. One of the factors that distinguishes MRI from other imaging methods is the ability to program the MRI system to reveal a wide range of imaging contrasts, where each type of contrast offers unique information about the biological sample of interest. This ability stems from the fact that both the amplitude and phase of the magnetization of the underlying tissue can be manipulated to highlight different biological phenomenon. The flexibility and capabilities offered by modern MRI systems have enabled the development of a myriad of techniques for characterizing anatomy, physiology, and function. These include methods to characterize gross anatomy, tissue microstructure, bulk blood flow, tissue perfusion, and functional changes in blood oxygenation. This article is categorized under: Laboratory Methods and Technologies > Imaging Translational, Genomic, and Systems Medicine > Diagnostic Methods.
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Affiliation(s)
- Thomas T Liu
- Center for Functional MRI and Departments of Radiology, Psychiatry, and Bioengineering, University of California San Diego, La Jolla, California
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44
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Dong SZ, Zhu M, Bulas D. Techniques for minimizing sedation in pediatric MRI. J Magn Reson Imaging 2019; 50:1047-1054. [PMID: 30869831 DOI: 10.1002/jmri.26703] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 02/17/2019] [Accepted: 02/19/2019] [Indexed: 12/16/2022] Open
Abstract
MRI is used widely in infants and young children. However, in these young cases deep sedation or general anesthesia is often required to minimize motion artifacts during MRI examinations. Although the benefits of MR typically outweigh the potential risks of sedation when delivered by an experienced team, there are increasing concerns regarding the affect of sedation on young children. There continues to be a push to develop various strategies that can minimize the need for sedation. The present review summarizes several technical and clinical approaches that can help decrease the need for sedation in the pediatric patient. Optimization of the MRI environment, the role of child life specialists, feed-and-bundle and distraction techniques, noise-reduction methods, artificial intelligence, and MRI advances to decrease both scan times and motion artifacts will be discussed. Level of Evidence: 5 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019.
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Affiliation(s)
- Su-Zhen Dong
- Department of Radiology, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Diagnostic Imaging and Radiology, Children's National Health Systems, Washington, DC, USA
| | - Ming Zhu
- Department of Radiology, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Dorothy Bulas
- Department of Diagnostic Imaging and Radiology, Children's National Health Systems, Washington, DC, USA
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Odéen H, Parker DL. Magnetic resonance thermometry and its biological applications - Physical principles and practical considerations. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 110:34-61. [PMID: 30803693 PMCID: PMC6662927 DOI: 10.1016/j.pnmrs.2019.01.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 01/23/2019] [Indexed: 05/25/2023]
Abstract
Most parameters that influence the magnetic resonance imaging (MRI) signal experience a temperature dependence. The fact that MRI can be used for non-invasive measurements of temperature and temperature change deep inside the human body has been known for over 30 years. Today, MR temperature imaging is widely used to monitor and evaluate thermal therapies such as radio frequency, microwave, laser, and focused ultrasound therapy. In this paper we cover the physical principles underlying the biological applications of MR temperature imaging and discuss practical considerations and remaining challenges. For biological tissue, the MR signal of interest comes mostly from hydrogen protons of water molecules but also from protons in, e.g., adipose tissue and various metabolites. Most of the discussed methods, such as those using the proton resonance frequency (PRF) shift, T1, T2, and diffusion only measure temperature change, but measurements of absolute temperatures are also possible using spectroscopic imaging methods (taking advantage of various metabolite signals as internal references) or various types of contrast agents. Currently, the PRF method is the most used clinically due to good sensitivity, excellent linearity with temperature, and because it is largely independent of tissue type. Because the PRF method does not work in adipose tissues, T1- and T2-based methods have recently gained interest for monitoring temperature change in areas with high fat content such as the breast and abdomen. Absolute temperature measurement methods using spectroscopic imaging and contrast agents often offer too low spatial and temporal resolution for accurate monitoring of ablative thermal procedures, but have shown great promise in monitoring the slower and usually less spatially localized temperature change observed during hyperthermia procedures. Much of the current research effort for ablative procedures is aimed at providing faster measurements, larger field-of-view coverage, simultaneous monitoring in aqueous and adipose tissues, and more motion-insensitive acquisitions for better precision measurements in organs such as the heart, liver, and kidneys. For hyperthermia applications, larger coverage, motion insensitivity, and simultaneous aqueous and adipose monitoring are also important, but great effort is also aimed at solving the problem of long-term field drift which gets interpreted as temperature change when using the PRF method.
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Affiliation(s)
- Henrik Odéen
- University of Utah, Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, 729 Arapeen Drive, Salt Lake City, UT 84108-1217, USA.
| | - Dennis L Parker
- University of Utah, Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, 729 Arapeen Drive, Salt Lake City, UT 84108-1217, USA.
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46
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Janos S, Schooler GR, Ngo JS, Davis JT. Free-breathing unsedated MRI in children: Justification and techniques. J Magn Reson Imaging 2019; 50:365-376. [DOI: 10.1002/jmri.26644] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/20/2018] [Accepted: 12/20/2018] [Indexed: 12/16/2022] Open
Affiliation(s)
- Sara Janos
- Department of Radiology; Duke University Medical Center; Durham North Carolina USA
| | - Gary R. Schooler
- Department of Radiology; Duke University Medical Center; Durham North Carolina USA
| | - Jennifer S. Ngo
- Department of Radiology; Duke University Medical Center; Durham North Carolina USA
| | - Joseph T. Davis
- Department of Radiology; Duke University Medical Center; Durham North Carolina USA
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MRI assessment of surrounding tissues in soft-tissue sarcoma during neoadjuvant chemotherapy can help predicting response and prognosis. Eur J Radiol 2018; 109:178-187. [DOI: 10.1016/j.ejrad.2018.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 10/03/2018] [Accepted: 11/04/2018] [Indexed: 12/14/2022]
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Roeloffs V, Rosenzweig S, Holme HCM, Uecker M, Frahm J. Frequency-modulated SSFP with radial sampling and subspace reconstruction: A time-efficient alternative to phase-cycled bSSFP. Magn Reson Med 2018; 81:1566-1579. [PMID: 30357904 DOI: 10.1002/mrm.27505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 07/05/2018] [Accepted: 08/03/2018] [Indexed: 11/11/2022]
Abstract
PURPOSE A novel subspace-based reconstruction method for frequency-modulated balanced steady-state free precession (fmSSFP) MRI is presented. In this work, suitable data acquisition schemes, subspace sizes, and efficiencies for banding removal are investigated. THEORY AND METHODS By combining a fmSSFP MRI sequence with a 3D stack-of-stars trajectory, scan efficiency is maximized as spectral information is obtained without intermediate preparation phases. A memory-efficient reconstruction routine is implemented by introducing the low-frequency Fourier transform as a subspace which allows for the formulation of a convex reconstruction problem. The removal of banding artifacts is investigated by comparing the proposed acquisition and reconstruction technique to phase-cycled bSSFP MRI. Aliasing properties of different undersampling schemes are analyzed and water/fat separation is demonstrated by reweighting the reconstructed subspace coefficients to generate virtual spectral responses in a post-processing step. RESULTS A simple root-of-sum-of-squares combination of the reconstructed subspace coefficients yields high-SNR images with the characteristic bSSFP contrast but without banding artifacts. Compared to Golden-Angle trajectories, turn-based sampling schemes were superior in minimizing aliasing across reconstructed subspace coefficients. Water/fat separated images of the human knee were obtained by reweighting subspace coefficients. CONCLUSIONS The novel subspace-based fmSSFP MRI technique emerges as a time-efficient alternative to phase-cycled bSFFP. The method does not need intermediate preparation phases, offers high SNR and avoids banding artifacts. Reweighting of the reconstructed subspace coefficients allows for generating virtual spectral responses with applications to water/fat separation.
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Affiliation(s)
- Volkert Roeloffs
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany
| | - Sebastian Rosenzweig
- Institute for Diagnostic and Interventional Radiology, University Medical Center, Göttingen, Germany.,German Centre for Cardiovascular Research (DZHK), Göttingen, Germany
| | - H Christian M Holme
- Institute for Diagnostic and Interventional Radiology, University Medical Center, Göttingen, Germany.,German Centre for Cardiovascular Research (DZHK), Göttingen, Germany
| | - Martin Uecker
- Institute for Diagnostic and Interventional Radiology, University Medical Center, Göttingen, Germany.,German Centre for Cardiovascular Research (DZHK), Göttingen, Germany
| | - Jens Frahm
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.,German Centre for Cardiovascular Research (DZHK), Göttingen, Germany
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Körzdörfer G, Jiang Y, Speier P, Pang J, Ma D, Pfeuffer J, Hensel B, Gulani V, Griswold M, Nittka M. Magnetic resonance field fingerprinting. Magn Reson Med 2018; 81:2347-2359. [PMID: 30320925 DOI: 10.1002/mrm.27558] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/12/2018] [Accepted: 09/14/2018] [Indexed: 12/17/2022]
Abstract
PURPOSE To develop and evaluate the magnetic resonance field fingerprinting method that simultaneously generates T1 , T2 , B0 , and B 1 + maps from a single continuous measurement. METHODS An encoding pattern was designed to integrate true fast imaging with steady-state precession (TrueFISP), fast imaging with steady-state precession (FISP), and fast low-angle shot (FLASH) sequence segments with varying flip angles, radio frequency (RF) phases, TEs, and gradient moments in a continuous acquisition. A multistep matching process was introduced that includes steps for integrated spiral deblurring and the correction of intravoxel phase dispersion. The method was evaluated in phantoms as well as in vivo studies in brain and lower abdomen. RESULTS Simultaneous measurement of T1 , T2 , B0 , and B 1 + is achieved with T1 and T2 subsequently being less afflicted by B0 and B 1 + variations. Phantom results demonstrate the stability of generated parameter maps. Higher undersampling factors and spatial resolution can be achieved with the proposed method as compared with solely FISP-based magnetic resonance fingerprinting. High-resolution B0 maps can potentially be further used as diagnostic information. CONCLUSION The proposed magnetic resonance field fingerprinting method can estimate T1 , T2 , B0 , and B 1 + maps accurately in phantoms, in the brain, and in the lower abdomen.
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Affiliation(s)
- Gregor Körzdörfer
- Siemens Healthcare GmbH, Erlangen, Germany.,Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Yun Jiang
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio
| | | | - Jianing Pang
- Siemens Medical Solutions USA, Chicago, Illinois
| | - Dan Ma
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio
| | | | - Bernhard Hensel
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Vikas Gulani
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio.,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Mark Griswold
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio.,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
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Wu X, Auerbach EJ, Vu AT, Moeller S, Van de Moortele PF, Yacoub E, Uğurbil K. Human Connectome Project-style resting-state functional MRI at 7 Tesla using radiofrequency parallel transmission. Neuroimage 2018; 184:396-408. [PMID: 30237033 DOI: 10.1016/j.neuroimage.2018.09.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 09/13/2018] [Accepted: 09/15/2018] [Indexed: 01/16/2023] Open
Abstract
We investigate the utility of radiofrequency (RF) parallel transmission (pTx) for whole-brain resting-state functional MRI (rfMRI) acquisition at 7 Tesla (7T). To this end, Human Connectome Project (HCP)-style data acquisitions were chosen as a showcase example. Five healthy subjects were scanned in pTx and single-channel transmit (1Tx) modes. The pTx data were acquired using a prototype 16-channel transmit system and a commercially available Nova 8-channel transmit 32-channel receive RF head coil. Additionally, pTx single-spoke multiband (MB) pulses were designed to image sagittal slices. HCP-style 7T rfMRI data (1.6-mm isotropic resolution, 5-fold slice and 2-fold in-plane acceleration, 3600 image volumes and ∼ 1-h scan) were acquired with pTx and the results were compared to those acquired with the original 7T HCP rfMRI protocol. The use of pTx significantly improved flip-angle uniformity across the brain, with coefficient of variation (i.e., std/mean) of whole-brain flip-angle distribution reduced on average by ∼39%. This in turn yielded ∼17% increase in group temporal SNR (tSNR) as averaged across the entire brain and ∼10% increase in group functional contrast-to-noise ratio (fCNR) as averaged across the grayordinate space (including cortical surfaces and subcortical voxels). Furthermore, when placing a seed in either the posterior parietal lobe or putamen to estimate seed-based dense connectome, the increase in fCNR was observed to translate into stronger correlation of the seed with the rest of the grayordinate space. We have demonstrated the utility of pTx for slice-accelerated high-resolution whole-brain rfMRI at 7T; as compared to current state-of-the-art, the use of pTx improves flip-angle uniformity, increases tSNR, enhances fCNR and strengthens functional connectivity estimation.
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Affiliation(s)
- Xiaoping Wu
- Center for Magnetic Resonance Research, Radiology, Medical School, University of Minnesota, Minneapolis, MN, United States.
| | - Edward J Auerbach
- Center for Magnetic Resonance Research, Radiology, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - An T Vu
- Center for Imaging of Neurodegenerative Diseases, VA Healthcare System, San Francisco, CA, United States
| | - Steen Moeller
- Center for Magnetic Resonance Research, Radiology, Medical School, University of Minnesota, Minneapolis, MN, United States
| | | | - Essa Yacoub
- Center for Magnetic Resonance Research, Radiology, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Kâmil Uğurbil
- Center for Magnetic Resonance Research, Radiology, Medical School, University of Minnesota, Minneapolis, MN, United States
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