1
|
Kofler A, Wald C, Kolbitsch C, V Tycowicz C, Ambellan F. Joint reconstruction and segmentation in undersampled 3D knee MRI combining shape knowledge and deep learning. Phys Med Biol 2024; 69:095022. [PMID: 38527376 DOI: 10.1088/1361-6560/ad3797] [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: 10/16/2023] [Accepted: 03/25/2024] [Indexed: 03/27/2024]
Abstract
Objective.Task-adapted image reconstruction methods using end-to-end trainable neural networks (NNs) have been proposed to optimize reconstruction for subsequent processing tasks, such as segmentation. However, their training typically requires considerable hardware resources and thus, only relatively simple building blocks, e.g. U-Nets, are typically used, which, albeit powerful, do not integrate model-specific knowledge.Approach.In this work, we extend an end-to-end trainable task-adapted image reconstruction method for a clinically realistic reconstruction and segmentation problem of bone and cartilage in 3D knee MRI by incorporating statistical shape models (SSMs). The SSMs model the prior information and help to regularize the segmentation maps as a final post-processing step. We compare the proposed method to a simultaneous multitask learning approach for image reconstruction and segmentation (MTL) and to a complex SSMs-informed segmentation pipeline (SIS).Main results.Our experiments show that the combination of joint end-to-end training and SSMs to further regularize the segmentation maps obtained by MTL highly improves the results, especially in terms of mean and maximal surface errors. In particular, we achieve the segmentation quality of SIS and, at the same time, a substantial model reduction that yields a five-fold decimation in model parameters and a computational speedup of an order of magnitude.Significance.Remarkably, even for undersampling factors of up toR= 8, the obtained segmentation maps are of comparable quality to those obtained by SIS from ground-truth images.
Collapse
Affiliation(s)
- A Kofler
- Physikalisch-Technische Bundesanstalt, Braunschweig and Berlin, Germany
| | - C Wald
- Department of Mathematics, Technical University of Berlin, Berlin, Germany
| | - C Kolbitsch
- Physikalisch-Technische Bundesanstalt, Braunschweig and Berlin, Germany
| | - C V Tycowicz
- Department of Visual and Data-Centric Computing, Zuse Institute Berlin, Berlin, Germany
| | - F Ambellan
- Department of Visual and Data-Centric Computing, Zuse Institute Berlin, Berlin, Germany
| |
Collapse
|
2
|
Contijoch F, Rasche V, Seiberlich N, Peters DC. The future of CMR: All-in-one vs. real-time CMR (Part 2). J Cardiovasc Magn Reson 2024; 26:100998. [PMID: 38237901 DOI: 10.1016/j.jocmr.2024.100998] [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: 12/21/2023] [Accepted: 01/10/2024] [Indexed: 02/20/2024] Open
Abstract
Cardiac Magnetic Resonance (CMR) protocols can be lengthy and complex, which has driven the research community to develop new technologies to make these protocols more efficient and patient-friendly. Two different approaches to improving CMR have been proposed, specifically "all-in-one" CMR, where several contrasts and/or motion states are acquired simultaneously, and "real-time" CMR, in which the examination is accelerated to avoid the need for breathholding and/or cardiac gating. The goal of this two-part manuscript is to describe these two different types of emerging rapid CMR protocols. To this end, the vision of all-in-one and real-time imaging are described, along with techniques which have been devised and tested along the pathway of clinical implementation. The pros and cons of the different methods are presented, and the remaining open needs of each are detailed. Part 1 tackles the "All-in-One" approaches, and Part 2 focuses on the "Real-Time" approaches along with an overall summary of these emerging methods.
Collapse
Affiliation(s)
| | - Volker Rasche
- Ulm University Medical Center, Department of Internal Medicine II, Ulm, Germany
| | - Nicole Seiberlich
- Michigan Institute for Imaging Technology and Translation, Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | | |
Collapse
|
3
|
Wang Z, Feng X, Salerno M, Kramer CM, Meyer CH. Dynamic cardiac MRI with high spatiotemporal resolution using accelerated spiral-out and spiral-in/out bSSFP pulse sequences at 1.5 T. MAGMA (NEW YORK, N.Y.) 2023; 36:857-867. [PMID: 37665502 PMCID: PMC10667461 DOI: 10.1007/s10334-023-01116-9] [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: 04/28/2023] [Revised: 08/06/2023] [Accepted: 08/16/2023] [Indexed: 09/05/2023]
Abstract
OBJECTIVE To develop two spiral-based bSSFP pulse sequences combined with L + S reconstruction for accelerated ungated, free-breathing dynamic cardiac imaging at 1.5 T. MATERIALS AND METHODS Tiny golden angle rotated spiral-out and spiral-in/out bSSFP sequences combined with view-sharing (VS), compressed sensing (CS), and low-rank plus sparse (L + S) reconstruction were evaluated and compared via simulation and in vivo dynamic cardiac imaging studies. The proposed methods were then validated against the standard cine, in terms of quantitative image assessment and qualitative quality rating. RESULTS The L + S method yielded the least residual artifacts and the best image sharpness among the three methods. Both spiral cine techniques showed clinically diagnostic images (score > 3). Compared to standard cine, there were significant differences in global image quality and edge sharpness for spiral cine techniques, while there was significant difference in image contrast for the spiral-out cine but no significant difference for the spiral-in/out cine. There was good agreement in left ventricular ejection fraction for both the spiral-out cine (- 1.6 [Formula: see text] 3.1%) and spiral-in/out cine (- 1.5 [Formula: see text] 2.8%) against standard cine. DISCUSSION Compared to the time-consuming standard cine (~ 5 min) which requires ECG-gating and breath-holds, the proposed spiral bSSFP sequences achieved ungated, free-breathing cardiac movies at a similar spatial (1.5 × 1.5 × 8 mm3) and temporal resolution (36 ms) per slice for whole heart coverage (10-15 slices) within 45 s, suggesting the clinical potential for improved patient comfort or for imaging patients with arrhythmias or who cannot hold their breath.
Collapse
Affiliation(s)
- Zhixing Wang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Xue Feng
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Michael Salerno
- School of Medicine, University Medical Line, Stanford University, Stanford, CA, USA
| | - Christopher M Kramer
- Cardiovascular Division, Department of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA
| | - Craig H Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA.
| |
Collapse
|
4
|
Çavuşoğlu M. Arterial spin labeling MRI using spiral acquisitions and concurrent field monitoring. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 356:107572. [PMID: 37847985 DOI: 10.1016/j.jmr.2023.107572] [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: 06/05/2023] [Revised: 09/25/2023] [Accepted: 10/09/2023] [Indexed: 10/19/2023]
Abstract
Perfusion MRI based on arterial spin labeling (ASL) has intrinsically very low signal-to-noise ratio (SNR). Signal acquisition at shorter echo times (TE) is necessary to boost the SNR of the ASL images. Spiral trajectories provide substantially shorter TE yielding increased SNR and are among the fastest k-space sampling schemes to encode a given field of view and resolution. Moreover, they provide approximately isotropic point-spread functions and inherent refocusing of motion- and flow-induced phase errors. However, the efficiency of the spiral acquisitions in ASL-MRI has been limited because these advantages are counterbalanced by practical technical challenges. This is because spiral acquisitions are highly sensitive to encoding deficiencies such as static off-resonance in the main magnetic field manifested as blurring artifacts in the image. Moreover, deviation of the gradient fields from the nominal waveforms due to the imperfection of the employed hardware critically limits the practical utilization of spiral trajectories. In this work, I provide single- and multiple-shot spiral ASL images that are robust against typical spiral encoding drawbacks enabled by deploying a comprehensive signal model involving static off-resonance and coil sensitivity maps and actual B0 and gradient field dynamics up to third order in space. The spiral ASL signal acquisition was concurrently monitored using a 3rd order dynamic field camera based on NMR field probes. The reconstructed ASL images at 3 mm and 2 mm in-plane resolution associating with the monitored field dynamics and the static off-resonances exhibited strongly reduced blurring- and aliasing artifacts and distortion. Concurrent field monitoring also enables to account for quasi-static B0 drifts by encompassing the parametric input data with consistent encoding geometry and physiological field fluctuations. In conclusion, concurrent field monitoring in spiral ASL acquisition largely overcomes traditional vulnerability of spiral trajectories in practice providing high quality ASL images with increased SNR, speed and motion robustness.
Collapse
Affiliation(s)
- Mustafa Çavuşoğlu
- Institute for Biomedical Engineering, University and ETH Zürich, Zürich, Switzerland; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland.
| |
Collapse
|
5
|
Zhang Y, He W, Yang L, Xuan L, Wu J, He Y, Guo Y, Xu Z. Efficient imaging using spiral acquisitions on a portable 50-mT MR head scanner. NMR IN BIOMEDICINE 2023; 36:e4988. [PMID: 37381057 DOI: 10.1002/nbm.4988] [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: 03/13/2023] [Revised: 05/21/2023] [Accepted: 05/22/2023] [Indexed: 06/30/2023]
Abstract
Ultralow-field (ULF) magnetic resonance imaging (MRI) can suffer from inferior image quality because of low signal-to-noise ratio (SNR). As an efficient way to cover the k-space, the spiral acquisition technique has shown great potential in improving imaging SNR efficiency at ULF. The current study aimed to address the problems of noise and blurring cancelation in the ULF case with spiral trajectory, and we proposed a spiral-out sequence for brain imaging using a portable 50-mT MRI system. The proposed sequence consisted of three modules: noise calibration, field map acquisition, and imaging. In the calibration step, transfer coefficients were obtained between signals from primary and noise-pick-up coils to perform electromagnetic interference (EMI) cancelation. Embedded field map acquisition was performed to correct accumulated phase error due to main field inhomogeneity. Considering imaging SNR, a lower bandwidth for data sampling was adopted in the sequence design because the 50-mT scanner is in a low SNR regime. Image reconstruction proceeded with sampled data by leveraging system imperfections, such as gradient delays and concomitant fields. The proposed method can provide images with higher SNR efficiency compared with its Cartesian counterparts. An improvement in temporal SNR of approximately 23%-44% was measured via phantom and in vivo experiments. Distortion-free images with a noise suppression rate of nearly 80% were obtained by the proposed technique. A comparison was also made with a state-of-the-art EMI cancelation algorithm used in the ULF-MRI system. SNR efficiency-enhanced spiral acquisitions were investigated for ULF-MR scanners and future studies could focus on various image contrasts based on our proposed approach to widen ULF applications.
Collapse
Affiliation(s)
- Yuxiang Zhang
- School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Wei He
- School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Lei Yang
- School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Liang Xuan
- School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Jiamin Wu
- Shenzhen Academy of Aerospace Technology, Shenzhen, China
- Harbin Institute of Technology, Harbin, China
| | - Yucheng He
- Shenzhen Academy of Aerospace Technology, Shenzhen, China
| | - Yi Guo
- Chongqing University Central Hospital, Chongqing, China
| | - Zheng Xu
- School of Electrical Engineering, Chongqing University, Chongqing, China
| |
Collapse
|
6
|
Knaus KR, Handsfield GG, Fiorentino NM, Hart JM, Meyer CH, Blemker SS. Athlete Muscular Phenotypes Identified and Compared with High-Dimensional Clustering of Lower Limb Muscle Volume Measurements. Med Sci Sports Exerc 2023; 55:1913-1922. [PMID: 37259254 DOI: 10.1249/mss.0000000000003224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
INTRODUCTION Athletes use their skeletal muscles to demonstrate performance. Muscle force generating capacity is correlated with volume, meaning that variations in sizes of different muscles may be indicative of how athletes meet different demands in their sports. Medical imaging enables in vivo quantification of muscle volumes; however, muscle volume distribution has not been compared across athletes of different sports. PURPOSE The goal of this work was to define "muscular phenotypes" in athletes of different sports and compare these using hierarchical clustering. METHODS Muscle volumes normalized by body mass of athletes (football, baseball, basketball, or track) were compared with control participants to quantify size differences using z -scores. z -Scores of 35 muscles described the pattern of volume deviation within each athlete's lower limb, characterizing their muscular phenotype. Data-driven high-dimensional clustering analysis was used to group athletes presenting similar phenotypes. Efficacy of clustering to identify similar phenotypes was demonstrated by grouping athletes' contralateral limbs before other athletes' limbs. RESULTS Analyses revealed that athletes did not tend to cluster with others competing in the same sport. Basketball players with similar phenotypes grouped by clustering also demonstrated similarities in performance. Clustering also identified muscles with similar volume variation patterns across athletes, and principal component analysis revealed specific muscles that accounted for most of the variance (gluteus maximus, sartorius, semitendinosus, vastus medialis, vastus lateralis, and rectus femoris). CONCLUSIONS Athletes exhibit heterogeneous lower limb muscle volumes that can be characterized and compared as individual muscular phenotypes. Clustering revealed that athletes with the most similar phenotypes do not always play the same sport such that patterns of muscular heterogeneity across a group of athletes reflect factors beyond their specific sports.
Collapse
Affiliation(s)
- Katherine R Knaus
- Department of Bioengineering, University of California San Diego, La Jolla, CA
| | | | | | - Joseph M Hart
- Department of Orthopedic Surgery, University of North Carolina, Chapel Hill, NC
| | | | | |
Collapse
|
7
|
Radhakrishna CG, Ciuciu P. Jointly Learning Non-Cartesian k-Space Trajectories and Reconstruction Networks for 2D and 3D MR Imaging through Projection. Bioengineering (Basel) 2023; 10:bioengineering10020158. [PMID: 36829652 PMCID: PMC9952463 DOI: 10.3390/bioengineering10020158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/27/2023] Open
Abstract
Compressed sensing in magnetic resonance imaging essentially involves the optimization of (1) the sampling pattern in k-space under MR hardware constraints and (2) image reconstruction from undersampled k-space data. Recently, deep learning methods have allowed the community to address both problems simultaneously, especially in the non-Cartesian acquisition setting. This work aims to contribute to this field by tackling some major concerns in existing approaches. Particularly, current state-of-the-art learning methods seek hardware compliant k-space sampling trajectories by enforcing the hardware constraints through additional penalty terms in the training loss. Through ablation studies, we rather show the benefit of using a projection step to enforce these constraints and demonstrate that the resulting k-space trajectories are more flexible under a projection-based scheme, which results in superior performance in reconstructed image quality. In 2D studies, our novel method trajectories present an improved image reconstruction quality at a 20-fold acceleration factor on the fastMRI data set with SSIM scores of nearly 0.92-0.95 in our retrospective studies as compared to the corresponding Cartesian reference and also see a 3-4 dB gain in PSNR as compared to earlier state-of-the-art methods. Finally, we extend the algorithm to 3D and by comparing optimization as learning-based projection schemes, we show that data-driven joint learning-based method trajectories outperform model-based methods such as SPARKLING through a 2 dB gain in PSNR and 0.02 gain in SSIM.
Collapse
Affiliation(s)
- Chaithya Giliyar Radhakrishna
- Neurospin, Commissariat à L’énergie Atomique et Aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, 91191 Gif-sur-Yvette, France
- Inria, Models and Inference for Neuroimaging Data (MIND), 91120 Palaiseau, France
| | - Philippe Ciuciu
- Neurospin, Commissariat à L’énergie Atomique et Aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, 91191 Gif-sur-Yvette, France
- Inria, Models and Inference for Neuroimaging Data (MIND), 91120 Palaiseau, France
- Correspondence:
| |
Collapse
|
8
|
Hennig J, Barghoorn A, Zhang S, Zaitsev M. Single shot spiral
TSE
with annulated segmentation. Magn Reson Med 2022; 88:651-662. [DOI: 10.1002/mrm.29224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/11/2022] [Accepted: 02/20/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Juergen Hennig
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
- Center for Basics in NeuroModulation (NeuroModulBasics) Faculty of Medicine, University of Freiburg Freiburg Germany
| | - Antonia Barghoorn
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
| | - Shuoyue Zhang
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
| | - Maxim Zaitsev
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
| |
Collapse
|
9
|
Wang Z, Allen SP, Feng X, Mugler JP, Meyer CH. SPRING-RIO TSE: 2D T 2 -Weighted Turbo Spin-Echo brain imaging using SPiral RINGs with retraced in/out trajectories. Magn Reson Med 2022; 88:601-616. [PMID: 35394088 PMCID: PMC9232877 DOI: 10.1002/mrm.29210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/29/2022] [Accepted: 02/09/2022] [Indexed: 11/11/2022]
Abstract
PURPOSE To develop a new approach to 2D turbo spin -echo (TSE) imaging using annular spiral rings with a retraced in/out trajectory, dubbed "SPRING-RIO TSE", for fast T2 -weighted brain imaging at 3T. METHODS A long spiral trajectory was split into annular segmentations that were then incorporated into a 2D TSE acquisition module to fully exploit the sampling efficiency of spiral rings. A retraced in/out trajectory strategy coupled with spiral-ring TSE was introduced to increase SNR, mitigate T2 -decay induced artifacts, and self-correct moderate off-resonance while maintaining the target TE and causing no scan time penalty. Model-based k-space estimation and semiautomatic off-resonance correction algorithms were implemented to minimize effects of k-space trajectory infidelity and B0 inhomogeneity, respectively. The resulting SPRING-RIO TSE method was compared to the original spiral-ring (abbreviated "SPRING") TSE and Cartesian TSE using simulations, and phantom and in vivo acquisitions. RESULTS Simulation and phantom studies demonstrated the performance of the proposed SPRING-RIO TSE pulses sequence, as well as that of trajectory correction and off-resonance correction. Volunteer data showed that the proposed method achieves high-quality 2D T2 -weighted brain imaging with a higher scan efficiency (0:45 min/14 slices versus 1:31 min/14 slices), improved image contrast, and reduced specific absorption rate compared to conventional 2D Cartesian TSE. CONCLUSION 2D T2 -weighted brain imaging using spiral-ring TSE was implemented and tested, providing several potential advantages over conventional 2D Cartesian TSE imaging.
Collapse
Affiliation(s)
- Zhixing Wang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Steven P Allen
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.,Department of Electrical and Computer Engineering, Brigham Young University, Provo, Utah, USA
| | - Xue Feng
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - John P Mugler
- Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Craig H Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.,Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| |
Collapse
|
10
|
Evaluation of axial gradient Echo spiral MRI of the spine at 1.5 T. Magn Reson Imaging 2022; 89:24-32. [DOI: 10.1016/j.mri.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/28/2022] [Accepted: 02/28/2022] [Indexed: 11/18/2022]
|
11
|
Advances in spiral fMRI: A high-resolution study with single-shot acquisition. Neuroimage 2021; 246:118738. [PMID: 34800666 DOI: 10.1016/j.neuroimage.2021.118738] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 10/23/2021] [Accepted: 11/15/2021] [Indexed: 01/15/2023] Open
Abstract
Spiral fMRI has been put forward as a viable alternative to rectilinear echo-planar imaging, in particular due to its enhanced average k-space speed and thus high acquisition efficiency. This renders spirals attractive for contemporary fMRI applications that require high spatiotemporal resolution, such as laminar or columnar fMRI. However, in practice, spiral fMRI is typically hampered by its reduced robustness and ensuing blurring artifacts, which arise from imperfections in both static and dynamic magnetic fields. Recently, these limitations have been overcome by the concerted application of an expanded signal model that accounts for such field imperfections, and its inversion by iterative image reconstruction. In the challenging ultra-high field environment of 7 Tesla, where field inhomogeneity effects are aggravated, both multi-shot and single-shot 2D spiral imaging at sub-millimeter resolution was demonstrated with high depiction quality and anatomical congruency. In this work, we further these advances towards a time series application of spiral readouts, namely, single-shot spiral BOLD fMRI at 0.8 mm in-plane resolution. We demonstrate that high-resolution spiral fMRI at 7 T is not only feasible, but delivers both excellent image quality, BOLD sensitivity, and spatial specificity of the activation maps, with little artifactual blurring. Furthermore, we show the versatility of the approach with a combined in/out spiral readout at a more typical resolution (1.5 mm), where the high acquisition efficiency allows to acquire two images per shot for improved sensitivity by echo combination.
Collapse
|
12
|
Javed A, Ramasawmy R, O'Brien K, Mancini C, Su P, Majeed W, Benkert T, Bhat H, Suffredini AF, Malayeri A, Campbell-Washburn AE. Self-gated 3D stack-of-spirals UTE pulmonary imaging at 0.55T. Magn Reson Med 2021; 87:1784-1798. [PMID: 34783391 DOI: 10.1002/mrm.29079] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/22/2021] [Accepted: 10/22/2021] [Indexed: 12/24/2022]
Abstract
PURPOSE To develop an isotropic high-resolution stack-of-spirals UTE sequence for pulmonary imaging at 0.55 Tesla by leveraging a combination of robust respiratory-binning, trajectory correction, and concomitant-field corrections. METHODS A stack-of-spirals golden-angle UTE sequence was used to continuously acquire data for 15.5 minutes. The data was binned to a stable respiratory phase based on superoinferior readout self-navigator signals. Corrections for trajectory errors and concomitant field artifacts, along with image reconstruction with conjugate gradient SENSE, were performed inline within the Gadgetron framework. Finally, data were retrospectively reconstructed to simulate scan times of 5, 8.5, and 12 minutes. Image quality was assessed using signal-to-noise, image sharpness, and qualitative reader scores. The technique was evaluated in healthy volunteers, patients with coronavirus disease 2019 infection, and patients with lung nodules. RESULTS The technique provided diagnostic quality images with parenchymal lung SNR of 3.18 ± 0.0.60, 4.57 ± 0.87, 5.45 ± 1.02, and 5.89 ± 1.28 for scan times of 5, 8.5, 12, and 15.5 minutes, respectively. The respiratory binning technique resulted in significantly sharper images (p < 0.001) as measured with relative maximum derivative at the diaphragm. Concomitant field corrections visibly improved sharpness of anatomical structures away from iso-center. The image quality was maintained with a slight loss in SNR for simulated scan times down to 8.5 minutes. Inline image reconstruction and artifact correction were achieved in <5 minutes. CONCLUSION The proposed pulmonary imaging technique combined efficient stack-of-spirals imaging with robust respiratory binning, concomitant field correction, and trajectory correction to generate diagnostic quality images with 1.75 mm isotropic resolution in 8.5 minutes on a high-performance 0.55 Tesla system.
Collapse
Affiliation(s)
- Ahsan Javed
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Rajiv Ramasawmy
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Kendall O'Brien
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Christine Mancini
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Pan Su
- Siemens Medical Solutions USA Inc., Malvern, Pennsylvania, USA
| | - Waqas Majeed
- Siemens Medical Solutions USA Inc., Malvern, Pennsylvania, USA
| | | | - Himanshu Bhat
- Siemens Medical Solutions USA Inc., Malvern, Pennsylvania, USA
| | - Anthony F Suffredini
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Ashkan Malayeri
- Department of Radiology and Imaging Sciences, Clinical Center, Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland, USA
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
13
|
Pipe JG, Borup DD. Generating spiral gradient waveforms with a compact frequency spectrum. Magn Reson Med 2021; 87:791-799. [PMID: 34519379 DOI: 10.1002/mrm.28993] [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: 05/17/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/11/2022]
Abstract
PURPOSE To generate efficient gradient waveforms for spiral MRI which mitigate the high-frequency attenuation inherent in gradient systems. THEORY AND METHODS Spiral MRI has many clinical advantages, including high temporal and SNR efficiency. One of the challenges for robust spiral MRI is a high sensitivity to imperfections in the gradient system, which requires some form of correction in order to map data correctly in k-space. A previous numerical algorithm for generating spiral gradient waveforms was modified to reduce its high-frequency content with minimal increase in waveform duration. RESULTS Examples are shown of compact frequency gradient waveforms. Software implementing the algorithm is made available. CONCLUSION An algorithm to produce gradient waveforms with a compact frequency spectrum is described. This algorithm results in greatly reduced overall error and better compatibility with gradient systems than the original algorithm from which it was derived.
Collapse
Affiliation(s)
- James G Pipe
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | |
Collapse
|
14
|
Vachha B, Huang SY. MRI with ultrahigh field strength and high-performance gradients: challenges and opportunities for clinical neuroimaging at 7 T and beyond. Eur Radiol Exp 2021; 5:35. [PMID: 34435246 PMCID: PMC8387544 DOI: 10.1186/s41747-021-00216-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/30/2021] [Indexed: 12/12/2022] Open
Abstract
Research in ultrahigh magnetic field strength combined with ultrahigh and ultrafast gradient technology has provided enormous gains in sensitivity, resolution, and contrast for neuroimaging. This article provides an overview of the technical advantages and challenges of performing clinical neuroimaging studies at ultrahigh magnetic field strength combined with ultrahigh and ultrafast gradient technology. Emerging clinical applications of 7-T MRI and state-of-the-art gradient systems equipped with up to 300 mT/m gradient strength are reviewed, and the impact and benefits of such advances to anatomical, structural and functional MRI are discussed in a variety of neurological conditions. Finally, an outlook and future directions for ultrahigh field MRI combined with ultrahigh and ultrafast gradient technology in neuroimaging are examined.
Collapse
Affiliation(s)
- Behroze Vachha
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA
| | - Susie Y Huang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149 13th Street, Room 2301, Charlestown, MA, 02129, USA.
| |
Collapse
|
15
|
Hajhosseiny R, Munoz C, Cruz G, Khamis R, Kim WY, Prieto C, Botnar RM. Coronary Magnetic Resonance Angiography in Chronic Coronary Syndromes. Front Cardiovasc Med 2021; 8:682924. [PMID: 34485397 PMCID: PMC8416045 DOI: 10.3389/fcvm.2021.682924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/23/2021] [Indexed: 01/14/2023] Open
Abstract
Cardiovascular disease is the leading cause of mortality worldwide, with atherosclerotic coronary artery disease (CAD) accounting for the majority of cases. X-ray coronary angiography and computed tomography coronary angiography (CCTA) are the imaging modalities of choice for the assessment of CAD. However, the use of ionising radiation and iodinated contrast agents remain drawbacks. There is therefore a clinical need for an alternative modality for the early identification and longitudinal monitoring of CAD without these associated drawbacks. Coronary magnetic resonance angiography (CMRA) could be a potential alternative for the detection and monitoring of coronary arterial stenosis, without exposing patients to ionising radiation or iodinated contrast agents. Further advantages include its versatility, excellent soft tissue characterisation and suitability for repeat imaging. Despite the early promise of CMRA, widespread clinical utilisation remains limited due to long and unpredictable scan times, onerous scan planning, lower spatial resolution, as well as motion related image quality degradation. The past decade has brought about a resurgence in CMRA technology, with significant leaps in image acceleration, respiratory and cardiac motion estimation and advanced motion corrected or motion-resolved image reconstruction. With the advent of artificial intelligence, great advances are also seen in deep learning-based motion estimation, undersampled and super-resolution reconstruction promising further improvements of CMRA. This has enabled high spatial resolution (1 mm isotropic), 3D whole heart CMRA in a clinically feasible and reliable acquisition time of under 10 min. Furthermore, latest super-resolution image reconstruction approaches which are currently under evaluation promise acquisitions as short as 1 min. In this review, we will explore the recent technological advances that are designed to bring CMRA closer to clinical reality.
Collapse
Affiliation(s)
- Reza Hajhosseiny
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Camila Munoz
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Gastao Cruz
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Ramzi Khamis
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Won Yong Kim
- Department of Cardiology and Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Denmark
| | - Claudia Prieto
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Escuela de Ingeniería, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - René M. Botnar
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Escuela de Ingeniería, Pontificia Universidad Catolica de Chile, Santiago, Chile
- Instituto de Ingeniería Biologica y Medica, Pontificia Universidad Catolica de Chile, Santiago, Chile
| |
Collapse
|
16
|
Feng X, Wang Z, Meyer CH. Real-time dynamic vocal tract imaging using an accelerated spiral GRE sequence and low rank plus sparse reconstruction. Magn Reson Imaging 2021; 80:106-112. [PMID: 33957210 DOI: 10.1016/j.mri.2021.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 03/17/2021] [Accepted: 04/29/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE To develop a real-time dynamic vocal tract imaging method using an accelerated spiral GRE sequence and low rank plus sparse reconstruction. METHODS Spiral k-space sampling has high data acquisition efficiency and thus is suited for real-time dynamic imaging; further acceleration can be achieved by undersampling k-space and using a model-based reconstruction. Low rank plus sparse reconstruction is a promising method with fast computation and increased robustness to global signal changes and bulk motion, as the images are decomposed into low rank and sparse terms representing different dynamic components. However, the combination with spiral scanning has not been well studied. In this study an accelerated spiral GRE sequence was developed with an optimized low rank plus sparse reconstruction and compared with L1-SPIRiT and XD-GRASP methods. The off-resonance was also corrected using a Chebyshev approximation method to reduce blurring on a frame-by-frame basis. RESULTS The low rank plus sparse reconstruction method is sensitive to the weights of the low rank and sparse terms. The optimized reconstruction showed advantages over other methods with reduced aliasing and improved SNR. With the proposed method, spatial resolution of 1.3*1.3 mm2 with 150 mm field-of-view (FOV) and temporal resolution of 30 frames-per-second (fps) was achieved with good image quality. Blurring was reduced using the Chebyshev approximation method. CONCLUSION This work studies low rank plus sparse reconstruction using the spiral trajectory and demonstrates a new method for dynamic vocal tract imaging which can benefit studies of speech disorders.
Collapse
Affiliation(s)
- Xue Feng
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
| | - Zhixing Wang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Craig H Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA
| |
Collapse
|
17
|
Kim JR, Yoon HM, Cho YA, Lee JS, Jung AY. Free-breathing contrast-enhanced upper abdominal MRI in children: comparison between Cartesian acquisition and stack-of-stars acquisition with two different fat-suppression techniques. Acta Radiol 2021; 62:541-550. [PMID: 32498544 DOI: 10.1177/0284185120928931] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Respiratory artifacts impair image quality of magnetic resonance imaging (MRI) in children who cannot hold breath during MRI examination. PURPOSE To compare the quality of free-breathing contrast-enhanced 3D T1-weighted (T1W) images of the upper abdomen in children using Cartesian acquisition (Cartesian eTHRIVE), stack-of-stars acquisition with spectral fat suppression (3D VANE eTHRIVE), and stack-of-stars acquisition with fat suppression using modified Dixon (3D VANE mDixon). MATERIAL AND METHODS Pediatric patients (aged <19 years) who underwent whole-body MRI with free-breathing contrast-enhanced T1W axial scans of upper abdomen using Cartesian eTHRIVE, 3D VANE eTHRIVE, and 3D VANE mDixon were enrolled. Image quality parameters were assessed including overall image quality, hepatic edge sharpness, hepatic vessel clarity, respiratory artifacts, radial artifacts, lesion conspicuity, and lesion edge sharpness using the Likert scale, where a lower score indicated poorer image quality. The coefficients of variation of signal intensity of liver and spleen were analyzed. RESULTS In 41 patients, 3D VANE eTHRIVE showed the highest scores for all image quality parameters (P ≤ 0.001). 3D VANE eTHRIVE also showed higher scores for respiratory (P ≤ 0.001) and radial artefacts than 3D VANE mDixon (P = 0.001). There were no significant differences in coefficients of variation of signal intensity of the liver and spleen between 3D VANE eTHRIVE and 3D VANE mDixon. Acquisition time was longer for 3D VANE eTHRIVE (81.26 ± 16 s) than for Cartesian eTHRIVE (7.87 ± 0.95 s) and 3D VANE mDixon (76.66 ± 12.4 s, P < 0.001). CONCLUSION The application of stack-of-stars acquisition to 3D T1W abdominal MRI resulted in better image quality than Cartesian acquisition in free-breathing children. In stack-of-stars acquisition, spectral fat suppression resulted in better image quality and fewer artifacts than mDixon.
Collapse
Affiliation(s)
- Jeong Rye Kim
- Department of Radiology, Dankook University Hospital, Chungcheongnam-do, Republic of Korea
| | - Hee Mang Yoon
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Young Ah Cho
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Jin Seong Lee
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Ah Young Jung
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| |
Collapse
|
18
|
Rahmer J, Schmale I, Mazurkewitz P, Lips O, Börnert P. Non-Cartesian k-space trajectory calculation based on concurrent reading of the gradient amplifiers' output currents. Magn Reson Med 2021; 85:3060-3070. [PMID: 33604921 DOI: 10.1002/mrm.28725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/23/2020] [Accepted: 01/19/2021] [Indexed: 11/07/2022]
Abstract
PURPOSE Non-Cartesian imaging sequences involve sampling during rapid variation of the encoding field gradients. The quality of the reconstructed images often suffers from insufficient knowledge of the exact dynamics of the actual fields applied during sampling. METHODS We propose determination of the accurate field dynamics by measuring the currents at the gradient amplifier outputs using the amplifiers' internal sensors concurrently with imaging. The actual dynamic field evolution is then determined by convolution with the measured current-to-field impulse response function of the gradient coil. Integration of the gradient field evolution allows derivation of the k-space trajectory for reconstruction. RESULTS The current-based approach is investigated in spiral and ultrashort TE phantom imaging. In comparison with the model-based product reconstruction as well as a correction approach based on the conventional input waveform-to-field impulse response function, it provides slightly improved image quality. The improvement is ascribed to a better representation of eddy current and amplifier nonlinearity effects. CONCLUSION Trajectory calculation based on measured amplifier output currents offers a robust, purely measurement-based alternative to conventional model-based approaches. The implementation can mitigate gradient amplifier imperfections with no or little additional hardware effort.
Collapse
Affiliation(s)
| | | | | | | | - Peter Börnert
- Philips Research, Hamburg, Germany.,Radiology, C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, Leiden, the Netherlands
| |
Collapse
|
19
|
Contijoch F, Han Y, Kamesh Iyer S, Kellman P, Gualtieri G, Elliott MA, Berisha S, Gorman JH, Gorman RC, Pilla JJ, Witschey WRT. Closed-loop control of k-space sampling via physiologic feedback for cine MRI. PLoS One 2020; 15:e0244286. [PMID: 33373391 PMCID: PMC7771662 DOI: 10.1371/journal.pone.0244286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/08/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Segmented cine cardiac MRI combines data from multiple heartbeats to achieve high spatiotemporal resolution cardiac images, yet predefined k-space segmentation trajectories can lead to suboptimal k-space sampling. In this work, we developed and evaluated an autonomous and closed-loop control system for radial k-space sampling (ARKS) to increase sampling uniformity. METHODS The closed-loop system autonomously selects radial k-space sampling trajectory during live segmented cine MRI and attempts to optimize angular sampling uniformity by selecting views in regions of k-space that were not previously well-sampled. Sampling uniformity and the ability to detect cardiac phase in vivo was assessed using ECG data acquired from 10 normal subjects in an MRI scanner. The approach was then implemented with a fast gradient echo sequence on a whole-body clinical MRI scanner and imaging was performed in 4 healthy volunteers. The closed-loop k-space trajectory was compared to random, uniformly distributed and golden angle view trajectories via measurement of k-space uniformity and the point spread function. Lastly, an arrhythmic dataset was used to evaluate a potential application of the approach. RESULTS The autonomous trajectory increased k-space sampling uniformity by 15±7%, main lobe point spread function (PSF) signal intensity by 6±4%, and reduced ringing relative to golden angle sampling. When implemented, the autonomous pulse sequence prescribed radial view angles faster than the scan TR (0.98 ± 0.01 ms, maximum = 1.38 ms) and increased k-space sampling mean uniformity by 10±11%, decreased uniformity variability by 44±12%, and increased PSF signal ratio by 6±6% relative to golden angle sampling. CONCLUSION The closed-loop approach enables near-uniform radial sampling in a segmented acquisition approach which was higher than predetermined golden-angle radial sampling. This can be utilized to increase the sampling or decrease the temporal footprint of an acquisition and the closed-loop framework has the potential to be applied to patients with complex heart rhythms.
Collapse
Affiliation(s)
- Francisco Contijoch
- Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, CA, United States of America
- Department of Radiology, School of Medicine, University of California, San Diego, CA, United States of America
| | - Yuchi Han
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Srikant Kamesh Iyer
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Peter Kellman
- National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States of America
| | | | - Mark A. Elliott
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Sebastian Berisha
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Joseph H. Gorman
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Robert C. Gorman
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - James J. Pilla
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Walter R. T. Witschey
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| |
Collapse
|
20
|
Eirich P, Wech T, Heidenreich JF, Stich M, Petri N, Nordbeck P, Bley TA, Köstler H. Cardiac real-time MRI using a pre-emphasized spiral acquisition based on the gradient system transfer function. Magn Reson Med 2020; 85:2747-2760. [PMID: 33270942 DOI: 10.1002/mrm.28621] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/21/2020] [Accepted: 11/10/2020] [Indexed: 12/28/2022]
Abstract
PURPOSE Segmented Cartesian acquisition in breath hold represents the current gold standard for cardiac functional MRI. However, it is also associated with long imaging times and severe restrictions in arrhythmic or dyspneic patients. Therefore, we introduce a real-time imaging technique based on a spoiled gradient-echo sequence with undersampled spiral k-space trajectories corrected by a gradient pre-emphasis. METHODS A fully automatic gradient waveform pre-emphasis based on the gradient system transfer function was implemented to compensate for gradient inaccuracies, to optimize fast double-oblique spiral MRI. The framework was tested in a phantom study and subsequently transferred to compressed sensing-accelerated cardiac functional MRI in real time. Spiral acquisitions during breath hold and free breathing were compared with this reference method for healthy subjects (N = 7) as well as patients (N = 2) diagnosed with heart failure and arrhythmia. Left-ventricular volumes and ejection fractions were determined and analyzed using a Wilcoxon signed-rank test. RESULTS The pre-emphasis successfully reduced typical artifacts caused by k-space misregistrations. Dynamic cardiac imaging was possible in real time (temporal resolution < 50 ms) with high spatial resolution (1.34 × 1.34 mm2 ), resulting in a total scan time of less than 50 seconds for whole heart coverage. Comparable image quality, as well as similar left-ventricular volumes and ejection fractions, were observed for the accelerated and the reference method. CONCLUSION The proposed technique enables high-resolution real-time cardiac MRI with no need for breath holds and electrocardiogram gating, shortening the duration of an entire functional cardiac exam to less than 1 minute.
Collapse
Affiliation(s)
- Philipp Eirich
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany.,Comprehensive Heart Failure Center Würzburg, Würzburg, Germany
| | - Tobias Wech
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Julius F Heidenreich
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Manuel Stich
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Nils Petri
- Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany
| | - Peter Nordbeck
- Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany
| | - Thorsten A Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Herbert Köstler
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| |
Collapse
|
21
|
Engel M, Kasper L, Wilm B, Dietrich B, Vionnet L, Hennel F, Reber J, Pruessmann KP. T-Hex: Tilted hexagonal grids for rapid 3D imaging. Magn Reson Med 2020; 85:2507-2523. [PMID: 33270941 DOI: 10.1002/mrm.28600] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 01/09/2023]
Abstract
PURPOSE The purpose of this work is to devise and demonstrate an encoding strategy for 3D MRI that reconciles high speed with flexible segmentation, uniform k-space density, and benign T 2 ∗ effects. METHODS Fast sampling of a 3D k-space is typically accomplished by 2D readouts per shot using EPI trains or spiral readouts. Tilted hexagonal (T-Hex) sampling is a way of acquiring more k-space volume per excitation while maintaining uniform sampling density and a smooth T 2 ∗ filter. The k-space volume covered per shot is controlled by the tilting angle. Image reconstruction is performed with a 3D extension of the iterative SENSE approach, incorporating actual field dynamics and static off-resonance. T-Hex imaging is compared with established 3D schemes in terms of speed and noise performance. RESULTS Tilted hexagonal acquisition is found to achieve greater imaging speed than known alternatives, particularly in combination with spiral trajectories. The interplay of the proposed 3D trajectories, array detection, and off-resonance is successfully addressed by iterative inversion of the full signal model. Enhanced coverage per shot is of greatest utility for high speed in an intermediate resolution regime of 1 to 4 mm. T-Hex EPI combines the benefits of extended coverage per shot with increased robustness against off-resonance effects. CONCLUSION Sampling of tilted hexagonal grids is a feasible means of gaining 3D imaging speed with near-optimal SNR efficiency and benign depiction properties. It is a particularly promising technique for time-resolved applications such as fMRI.
Collapse
Affiliation(s)
- Maria Engel
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Lars Kasper
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.,Translational Neuromodeling Unit, IBT, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Bertram Wilm
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Benjamin Dietrich
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Laetitia Vionnet
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Franciszek Hennel
- 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
| |
Collapse
|
22
|
Hajhosseiny R, Bustin A, Munoz C, Rashid I, Cruz G, Manning WJ, Prieto C, Botnar RM. Coronary Magnetic Resonance Angiography: Technical Innovations Leading Us to the Promised Land? JACC Cardiovasc Imaging 2020; 13:2653-2672. [PMID: 32199836 DOI: 10.1016/j.jcmg.2020.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 01/03/2020] [Accepted: 01/08/2020] [Indexed: 02/07/2023]
Abstract
Coronary artery disease remains the leading cause of cardiovascular morbidity and mortality. Invasive X-ray angiography and coronary computed tomography angiography are established gold standards for coronary luminography. However, they expose patients to invasive complications, ionizing radiation, and iodinated contrast agents. Among a number of imaging modalities, coronary cardiovascular magnetic resonance (CMR) angiography may be used in some cases as an alternative for the detection and monitoring of coronary arterial stenosis, with advantages including its versatility, excellent soft tissue characterization, and avoidance of ionizing radiation and iodinated contrast agents. In this review, we explore the recent advances in motion correction, image acceleration, and reconstruction technologies that are bringing coronary CMR angiography closer to widespread clinical implementation.
Collapse
Affiliation(s)
- Reza Hajhosseiny
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; National Heart and Lung Institute, Imperial College London, London, United Kingdom.
| | - Aurelien Bustin
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Camila Munoz
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Imran Rashid
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Gastao Cruz
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Warren J Manning
- Department of Medicine (Cardiovascular Division) and Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Claudia Prieto
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Escuela de Ingeniería, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - René M Botnar
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Escuela de Ingeniería, Pontificia Universidad Catolica de Chile, Santiago, Chile
| |
Collapse
|
23
|
Lim Y, Bliesener Y, Narayanan S, Nayak KS. Deblurring for spiral real-time MRI using convolutional neural networks. Magn Reson Med 2020; 84:3438-3452. [PMID: 32710516 PMCID: PMC7722023 DOI: 10.1002/mrm.28393] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 05/06/2020] [Accepted: 06/01/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE To develop and evaluate a fast and effective method for deblurring spiral real-time MRI (RT-MRI) using convolutional neural networks. METHODS We demonstrate a 3-layer residual convolutional neural networks to correct image domain off-resonance artifacts in speech production spiral RT-MRI without the knowledge of field maps. The architecture is motivated by the traditional deblurring approaches. Spatially varying off-resonance blur is synthetically generated by using discrete object approximation and field maps with data augmentation from a large database of 2D human speech production RT-MRI. The effect of off-resonance range, shift-invariance of blur, and readout durations on deblurring performance are investigated. The proposed method is validated using synthetic and real data with longer readouts, quantitatively using image quality metrics and qualitatively via visual inspection, and with a comparison to conventional deblurring methods. RESULTS Deblurring performance was found superior to a current autocalibrated method for in vivo data and only slightly worse than an ideal reconstruction with perfect knowledge of the field map for synthetic test data. Convolutional neural networks deblurring made it possible to visualize articulator boundaries with readouts up to 8 ms at 1.5 T, which is 3-fold longer than the current standard practice. The computation time was 12.3 ± 2.2 ms per frame, enabling low-latency processing for RT-MRI applications. CONCLUSION Convolutional neural networks deblurring is a practical, efficient, and field map-free approach for the deblurring of spiral RT-MRI. In the context of speech production imaging, this can enable 1.7-fold improvement in scan efficiency and the use of spiral readouts at higher field strengths such as 3 T.
Collapse
Affiliation(s)
- Yongwan Lim
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Yannick Bliesener
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Shrikanth Narayanan
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Krishna S. Nayak
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| |
Collapse
|
24
|
Zi R, Zhu D, Qin Q. Quantitative T 2 mapping using accelerated 3D stack-of-spiral gradient echo readout. Magn Reson Imaging 2020; 73:138-147. [PMID: 32860871 PMCID: PMC7571618 DOI: 10.1016/j.mri.2020.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 08/18/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE To develop a rapid T2 mapping protocol using optimized spiral acquisition, accelerated reconstruction, and model fitting. MATERIALS AND METHODS A T2-prepared stack-of-spiral gradient echo (GRE) pulse sequence was applied. A model-based approach joined with compressed sensing was compared with the two methods applied separately for accelerated reconstruction and T2 mapping. A 2-parameter-weighted fitting method was compared with 2- or 3-parameter models for accurate T2 estimation under the influences of noise and B1 inhomogeneity. The performance was evaluated using both digital phantoms and healthy volunteers. Mitigating partial voluming with cerebrospinal fluid (CSF) was also tested. RESULTS Simulations demonstrates that the 2-parameter-weighted fitting approach was robust to a large range of B1 scales and SNR levels. With an in-plane acceleration factor of 5, the model-based compressed sensing-incorporated method yielded around 8% normalized errors compared to references. The T2 estimation with and without CSF nulling was consistent with literature values. CONCLUSION This work demonstrated the feasibility of a T2 quantification technique with 3D high-resolution and whole-brain coverage in 2-3 min. The proposed iterative reconstruction method, which utilized the model consistency, data consistency and spatial sparsity jointly, provided reasonable T2 estimation. The technique also allowed mitigation of CSF partial volume effect.
Collapse
Affiliation(s)
- Ruoxun Zi
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Dan Zhu
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Qin Qin
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| |
Collapse
|
25
|
Greve T, Sollmann N, Hock A, Zimmer C, Kirschke JS. Novel Ultrafast Spiral Head MR Angiography Compared to Standard MR and CT Angiography. J Neuroimaging 2020; 31:45-56. [PMID: 33118692 DOI: 10.1111/jon.12791] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/10/2020] [Accepted: 09/14/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Intracranial vessel imaging by time-of-flight MR angiography (TOF-MRA) is one of the most frequently performed investigations in clinical neuroradiology. Particularly in the acute setting, fast imaging is needed for diagnostics, with a sequence ideally depicting even small vessels. The purpose of this study was to compare image and diagnostic quality of a novel ultrashort TOF-MRA sequence accelerated by spiral imaging (TOF-Spiral-short) to a standard TOF-MRA sequence accelerated by compressed sensing (TOF-CS) and to CT angiography (CTA). METHODS Forty-one patients (36.6% showing vessel pathologies) who had undergone TOF-CS (acquisition duration: 4 minutes 8 seconds), TOF-Spiral-short (acquisition duration: 51 seconds; spiral imaging [accelerating factor 1.3], decreased field of view [accelerating factor 1.2], and increased voxel size [accelerating factor 3.3]), and CTA were retrospectively evaluated. Assessment of image quality, diagnostic confidence, and quantification of stenosis or aneurysm diameter were performed by two readers. RESULTS Image quality at the skull base was slightly reduced with TOF-Spiral-short compared to CTA and TOF-CS (P < .05). Delineation of small intracranial vessels was improved by TOF-Spiral-short compared to CTA (P < .0001). In TOF-Spiral-short, diagnostic confidence was not reduced compared to TOF-CS in patients with vessel pathologies. We observed no significant difference in quantitative pathology assessment between TOF-Spiral-short and the other two modalities. TOF-Spiral-short enabled the correct identification of all vessel pathologies. CONCLUSIONS Accelerating TOF-MRA of brain-feeding arteries by a novel ultrashort spiral imaging sequence shows adequate image quality and sufficient diagnostic performance. Thus, TOF-Spiral-short holds potential for fast and reliable diagnostics of vessel pathologies, particularly in the acute setting.
Collapse
Affiliation(s)
- Tobias Greve
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,Department of Neurosurgery, University Hospital, Ludwig-Maximilians-University, Campus Grosshadern, Munich, Germany
| | - Nico Sollmann
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Andreas Hock
- Health Systems Philips Switzerland, Horgen, Switzerland
| | - Claus Zimmer
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Jan S Kirschke
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| |
Collapse
|
26
|
Xie T, Crump KB, Ni R, Meyer CH, Hart JM, Blemker SS, Feng X. Quantitative Relationships Between Individual Lower-Limb Muscle Volumes and Jump and Sprint Performances of Basketball Players. J Strength Cond Res 2020; 34:623-631. [PMID: 31703044 DOI: 10.1519/jsc.0000000000003421] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Xie, T, Crump, KB, Ni, R, Meyer, CH, Hart, JM, Blemker, SS, and Feng, X. Quantitative relationships between individual lower-limb muscle volumes and jump and sprint performances of basketball players. J Strength Cond Res 34(3): 623-631, 2020-Lower body skeletal muscles play an essential role in athletic performance; however, because of the difficulty in obtaining detailed information of each individual muscle, the quantitative relationships between individual muscle volumes and performance are not well studied. The aim of this study was to accurately measure individual muscle volumes and identify the muscles with strong correlations with jump and sprint performance metrics for basketball players. Ten male varsity basketball players and 8 club players were scanned using magnetic resonance imaging (MRI) and instructed to perform various jump and sprint tests. The volumes of all lower-limb muscles were calculated from MRI and normalized by body surface area to reduce the effect of the body size differences. In analysis, feature selection was first used to identify the most relevant muscles, followed by correlation analysis to quantify the relationships between the selected muscles and each performance metric. Vastus medialis and semimembranosus were found to be the most relevant muscles for jump while adductor longus and vastus medialis were selected for sprint. Strong correlations (r = 0.664-0.909) between the selected muscles and associated performance tests were found for varsity players, and moderate correlations (r = -0.203 to 0.635) were found for club players. One possible application is that for well-trained varsity players, a targeted training scheme focusing on the selected muscles may be an effective method to further improve jump and sprint performances.
Collapse
Affiliation(s)
| | | | - Renkun Ni
- Springbok, Inc., Charlottesville, VA
| | - Craig H Meyer
- Springbok, Inc., Charlottesville, VA.,Department of Biomedical Engineering, University of Virginia, Charlottesville, VA; and
| | - Joseph M Hart
- Springbok, Inc., Charlottesville, VA.,Department of Kinesiology, University of Virginia, Charlottesville, VA
| | - Silvia S Blemker
- Springbok, Inc., Charlottesville, VA.,Department of Biomedical Engineering, University of Virginia, Charlottesville, VA; and
| | - Xue Feng
- Springbok, Inc., Charlottesville, VA.,Department of Biomedical Engineering, University of Virginia, Charlottesville, VA; and
| |
Collapse
|
27
|
Tyler A, Lau JYC, Ball V, Timm KN, Zhou T, Tyler DJ, Miller JJ. A 3D hybrid-shot spiral sequence for hyperpolarized 13 C imaging. Magn Reson Med 2020; 85:790-801. [PMID: 32894618 PMCID: PMC7611357 DOI: 10.1002/mrm.28462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 06/30/2020] [Accepted: 07/14/2020] [Indexed: 01/30/2023]
Abstract
Purpose Hyperpolarized imaging experiments have conflicting requirements of high spatial, temporal, and spectral resolution. Spectral-spatial RF excitation has been shown to form an attractive magnetization-efficient method for hyperpolarized imaging, but the optimum readout strategy is not yet known. Methods In this work, we propose a novel 3D hybrid-shot spiral sequence which features two constant density regions that permit the retrospective reconstruction of either high spatial or high temporal resolution images post hoc, (adaptive spatiotemporal imaging) allowing greater flexibility in acquisition and reconstruction. Results We have implemented this sequence, both via simulation and on a preclinical scanner, to demonstrate its feasibility, in both a 1H phantom and with hyperpolarized 13C pyruvate in vivo. Conclusions This sequence forms an attractive method for acquiring hyperpolarized imaging datasets, providing adaptive spatiotemporal imaging to ameliorate the conflict of spatial and temporal resolution, with significant potential for clinical translation.
Collapse
Affiliation(s)
- Andrew Tyler
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom.,Oxford Centre for Clinical Cardiac Magnetic Resonance Research (OCMR), Level 0, John Radcliffe Hospital, Headington, United Kingdom
| | - Justin Y C Lau
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom.,Oxford Centre for Clinical Cardiac Magnetic Resonance Research (OCMR), Level 0, John Radcliffe Hospital, Headington, United Kingdom
| | - Vicky Ball
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Kerstin N Timm
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Tony Zhou
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom.,Oxford Centre for Clinical Cardiac Magnetic Resonance Research (OCMR), Level 0, John Radcliffe Hospital, Headington, United Kingdom
| | - Damian J Tyler
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom.,Oxford Centre for Clinical Cardiac Magnetic Resonance Research (OCMR), Level 0, John Radcliffe Hospital, Headington, United Kingdom
| | - Jack J Miller
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom.,Oxford Centre for Clinical Cardiac Magnetic Resonance Research (OCMR), Level 0, John Radcliffe Hospital, Headington, United Kingdom.,Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
28
|
Brunnquell CL, Hoff MN, Balu N, Nguyen XV, Oztek MA, Haynor DR. Making Magnets More Attractive: Physics and Engineering Contributions to Patient Comfort in MRI. Top Magn Reson Imaging 2020; 29:167-174. [PMID: 32541257 DOI: 10.1097/rmr.0000000000000246] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Patient comfort is an important factor of a successful magnetic resonance (MR) examination, and improvements in the patient's MR scanning experience can contribute to improved image quality, diagnostic accuracy, and efficiency in the radiology department, and therefore reduced cost. Magnet designs that are more open and accessible, reduced auditory noise of MR examinations, light and flexible radiofrequency (RF) coils, and faster motion-insensitive imaging techniques can all significantly improve the patient experience in MR imaging. In this work, we review the design, development, and implementation of these physics and engineering approaches to improve patient comfort.
Collapse
Affiliation(s)
- Christina L Brunnquell
- Department of Radiology, University of Washington, Seattle, WA Department of Radiology, The Ohio State University Wexler Medical Center, Columbus, OH
| | | | | | | | | | | |
Collapse
|
29
|
Börnert P, Norris DG. A half-century of innovation in technology-preparing MRI for the 21st century. Br J Radiol 2020; 93:20200113. [PMID: 32496816 DOI: 10.1259/bjr.20200113] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
MRI developed during the last half-century from a very basic concept to an indispensable non-ionising medical imaging technique that has found broad application in diagnostics, therapy control and far beyond. Due to its excellent soft-tissue contrast and the huge variety of accessible tissue- and physiological-parameters, MRI is often preferred to other existing modalities. In the course of its development, MRI underwent many substantial transformations. From the beginning, starting as a proof of concept, much effort was expended to develop the appropriate basic scanning technology and methodology, and to establish the many clinical contrasts (e.g., T1, T2, flow, diffusion, water/fat, etc.) that MRI is famous for today. Beyond that, additional prominent innovations to the field have been parallel imaging and compressed sensing, leading to significant scanning time reductions, and the move towards higher static magnetic field strengths, which led to increased sensitivity and improved image quality. Improvements in workflow and the use of artificial intelligence are among many current trends seen in this field, paving the way for a broad use of MRI. The 125th anniversary of the BJR is a good point to reflect on all these changes and developments and to offer some slightly speculative ideas as to what the future may bring.
Collapse
Affiliation(s)
- Peter Börnert
- Philips Research, Hamburg, Germany.,Department of Radiology, LUMC, Leiden, the Netherlands
| | - David G Norris
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.,Magnetic Detection and Imaging, Science and Technology Faculty, University of Twente, Enschede, Netherlands
| |
Collapse
|
30
|
Ong F, Uecker M, Lustig M. Accelerating Non-Cartesian MRI Reconstruction Convergence Using k-Space Preconditioning. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:1646-1654. [PMID: 31751232 PMCID: PMC7285911 DOI: 10.1109/tmi.2019.2954121] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We propose a k-space preconditioning formulation for accelerating the convergence of iterative Magnetic Resonance Imaging (MRI) reconstructions from non-uniformly sampled k-space data. Existing methods either use sampling density compensations which sacrifice reconstruction accuracy, or circulant preconditioners which increase per-iteration computation. Our approach overcomes both shortcomings. Concretely, we show that viewing the reconstruction problem in the dual formulation allows us to precondition in k-space using density-compensation-like operations. Using the primal-dual hybrid gradient method, the proposed preconditioning method does not have inner loops and are competitive in accelerating convergence compared to existing algorithms. We derive l2 -optimized preconditioners, and demonstrate through experiments that the proposed method converges in about ten iterations in practice.
Collapse
|
31
|
Restivo MC, Ramasawmy R, Bandettini WP, Herzka DA, Campbell-Washburn AE. Efficient spiral in-out and EPI balanced steady-state free precession cine imaging using a high-performance 0.55T MRI. Magn Reson Med 2020; 84:2364-2375. [PMID: 32291845 DOI: 10.1002/mrm.28278] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 03/10/2020] [Accepted: 03/13/2020] [Indexed: 12/22/2022]
Abstract
PURPOSE Low-field MRI offers favorable physical properties for SNR-efficient long readout acquisitions such as spiral and EPI. We used a 0.55 tesla (T) MRI system equipped with high-performance hardware to increase the sampling duty cycle and extend the TR of balanced steady-state free precession (bSSFP) cardiac cine acquisitions, which typically are limited by banding artifacts. METHODS We developed a high-efficiency spiral in-out bSSFP acquisition, with zeroth- and first-gradient moment nulling, and an EPI bSSFP acquisition for cardiac cine imaging using a contemporary MRI system modified to operate at 0.55T. Spiral in-out and EPI bSSFP cine protocols, with TR = 8 ms, were designed to maintain both spatiotemporal resolution and breath-hold length. Simulations, phantom imaging, and healthy volunteer imaging studies (n = 12) were performed to assess SNR and image quality using these high sampling duty-cycle bSSFP sequences. RESULTS Spiral in-out bSSFP performed favorably at 0.55T and generated good image quality, whereas EPI bSSFP suffered motion and flow artifacts. There was no difference in ejection fraction comparing spiral in-out with standard Cartesian imaging. Moreover, human images demonstrated a 79% ± 21% increase in myocardial SNR using spiral in-out bSSFP and 50% ± 14% increase in SNR using EPI bSSFP as compared with the reference Cartesian acquisition. Spiral in-out acquisitions at 0.55T recovered 69% ± 14% of the myocardial SNR at 1.5T. CONCLUSION Efficient bSSFP spiral in-out provided high-quality cardiac cine imaging and SNR recovery on a high-performance 0.55T MRI system.
Collapse
Affiliation(s)
- Matthew C Restivo
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Rajiv Ramasawmy
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - W Patricia Bandettini
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Daniel A Herzka
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| |
Collapse
|
32
|
Topping GJ, Hundshammer C, Nagel L, Grashei M, Aigner M, Skinner JG, Schulte RF, Schilling F. Acquisition strategies for spatially resolved magnetic resonance detection of hyperpolarized nuclei. MAGMA (NEW YORK, N.Y.) 2020; 33:221-256. [PMID: 31811491 PMCID: PMC7109201 DOI: 10.1007/s10334-019-00807-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 10/08/2019] [Accepted: 11/21/2019] [Indexed: 12/13/2022]
Abstract
Hyperpolarization is an emerging method in magnetic resonance imaging that allows nuclear spin polarization of gases or liquids to be temporarily enhanced by up to five or six orders of magnitude at clinically relevant field strengths and administered at high concentration to a subject at the time of measurement. This transient gain in signal has enabled the non-invasive detection and imaging of gas ventilation and diffusion in the lungs, perfusion in blood vessels and tissues, and metabolic conversion in cells, animals, and patients. The rapid development of this method is based on advances in polarizer technology, the availability of suitable probe isotopes and molecules, improved MRI hardware and pulse sequence development. Acquisition strategies for hyperpolarized nuclei are not yet standardized and are set up individually at most sites depending on the specific requirements of the probe, the object of interest, and the MRI hardware. This review provides a detailed introduction to spatially resolved detection of hyperpolarized nuclei and summarizes novel and previously established acquisition strategies for different key areas of application.
Collapse
Affiliation(s)
- Geoffrey J Topping
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Christian Hundshammer
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Luca Nagel
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Martin Grashei
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Maximilian Aigner
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jason G Skinner
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | | | - Franz Schilling
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
| |
Collapse
|
33
|
Benchmarking MRI Reconstruction Neural Networks on Large Public Datasets. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10051816] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Deep learning is starting to offer promising results for reconstruction in Magnetic Resonance Imaging (MRI). A lot of networks are being developed, but the comparisons remain hard because the frameworks used are not the same among studies, the networks are not properly re-trained, and the datasets used are not the same among comparisons. The recent release of a public dataset, fastMRI, consisting of raw k-space data, encouraged us to write a consistent benchmark of several deep neural networks for MR image reconstruction. This paper shows the results obtained for this benchmark, allowing to compare the networks, and links the open source implementation of all these networks in Keras. The main finding of this benchmark is that it is beneficial to perform more iterations between the image and the measurement spaces compared to having a deeper per-space network.
Collapse
|
34
|
Ooi MB, Li Z, Robison RK, Wang D, Anderson AG, Zwart NR, Bakhru A, Nagaraj S, Mathews T, Hey S, Koonen JJ, Dimitrov IE, Friel HT, Lu Q, Obara M, Saha I, Wang H, Wang Y, Zhao Y, Temkit M, Hu HH, Chenevert TL, Togao O, Tkach JA, Nagaraj UD, Pinho MC, Gupta RK, Small JE, Kunst MM, Karis JP, Andre JB, Miller JH, Pinter NK, Pipe JG. Spiral T1 Spin-Echo for Routine Postcontrast Brain MRI Exams: A Multicenter Multireader Clinical Evaluation. AJNR Am J Neuroradiol 2020; 41:238-245. [PMID: 32029467 DOI: 10.3174/ajnr.a6409] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/10/2019] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND PURPOSE Spiral MR imaging has several advantages compared with Cartesian MR imaging that can be leveraged for added clinical value. A multicenter multireader study was designed to compare spiral with standard-of-care Cartesian postcontrast structural brain MR imaging on the basis of relative performance in 10 metrics of image quality, artifact prevalence, and diagnostic benefit. MATERIALS AND METHODS Seven clinical sites acquired 88 total subjects. For each subject, sites acquired 2 postcontrast MR imaging scans: a spiral 2D T1 spin-echo, and 1 of 4 routine Cartesian 2D T1 spin-echo/TSE scans (fully sampled spin-echo at 3T, 1.5T, partial Fourier, TSE). The spiral acquisition matched the Cartesian scan for scan time, geometry, and contrast. Nine neuroradiologists independently reviewed each subject, with the matching pair of spiral and Cartesian scans compared side-by-side, and scored on 10 image-quality metrics (5-point Likert scale) focused on intracranial assessment. The Wilcoxon signed rank test evaluated relative performance of spiral versus Cartesian, while the Kruskal-Wallis test assessed interprotocol differences. RESULTS Spiral was superior to Cartesian in 7 of 10 metrics (flow artifact mitigation, SNR, GM/WM contrast, image sharpness, lesion conspicuity, preference for diagnosing abnormal enhancement, and overall intracranial image quality), comparable in 1 of 10 metrics (motion artifacts), and inferior in 2 of 10 metrics (susceptibility artifacts, overall extracranial image quality) related to magnetic susceptibility (P < .05). Interprotocol comparison confirmed relatively higher SNR and GM/WM contrast for partial Fourier and TSE protocol groups, respectively (P < .05). CONCLUSIONS Spiral 2D T1 spin-echo for routine structural brain MR imaging is feasible in the clinic with conventional scanners and was preferred by neuroradiologists for overall postcontrast intracranial evaluation.
Collapse
Affiliation(s)
- M B Ooi
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - Z Li
- Gainesville, Florida; Barrow Neurological Institute (Z.L., A.G.A., N.R.Z., J.P.K.)
| | - R K Robison
- Rochester, Minnesota; Phoenix Children's Hospital (R.K.R., M.T., H.H.H., J.H.M.)
| | - D Wang
- Phoenix, Arizona; Mayo Clinic (D.W., J.G.P.)
| | - A G Anderson
- Gainesville, Florida; Barrow Neurological Institute (Z.L., A.G.A., N.R.Z., J.P.K.)
| | - N R Zwart
- Gainesville, Florida; Barrow Neurological Institute (Z.L., A.G.A., N.R.Z., J.P.K.)
| | - A Bakhru
- Buffalo, New York; Philips Healthcare (A.B., S.N., T.M.)
| | - S Nagaraj
- Buffalo, New York; Philips Healthcare (A.B., S.N., T.M.)
| | - T Mathews
- Buffalo, New York; Philips Healthcare (A.B., S.N., T.M.)
| | - S Hey
- Bangalore, India; Philips Healthcare, (S.H., J.J.K.), Best, the Netherlands
| | - J J Koonen
- Bangalore, India; Philips Healthcare, (S.H., J.J.K.), Best, the Netherlands
| | - I E Dimitrov
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - H T Friel
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - Q Lu
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - M Obara
- Philips Healthcare (M.O.), Tokyo, Japan
| | - I Saha
- Philips Healthcare (I.S.), Gurgaon, India
| | - H Wang
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - Y Wang
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - Y Zhao
- From Philips Healthcare (M.B.O., I.E.D., H.T.F., Q.L., H.W., Y.W., Y.Z.)
| | - M Temkit
- Rochester, Minnesota; Phoenix Children's Hospital (R.K.R., M.T., H.H.H., J.H.M.)
| | - H H Hu
- Rochester, Minnesota; Phoenix Children's Hospital (R.K.R., M.T., H.H.H., J.H.M.)
| | - T L Chenevert
- University of Michigan (T.L.C.), Ann Arbor, Michigan
| | - O Togao
- Kyushu University Hospital (O.T.), Kyushu, Japan
| | - J A Tkach
- Cincinnati Children's Hospital (J.A.T., U.D.N.), Cincinnati, Ohio
| | - U D Nagaraj
- Cincinnati Children's Hospital (J.A.T., U.D.N.), Cincinnati, Ohio
| | - M C Pinho
- University of Texas Southwestern Medical Center (M.C.P.), Dallas, Texas
| | - R K Gupta
- Fortis Memorial Research Institute (R.K.G.), Gurgaon, India
| | - J E Small
- Lahey Hospital and Medical Center (J.E.S., M.M.K.), Burlington, Massachusetts
| | - M M Kunst
- Lahey Hospital and Medical Center (J.E.S., M.M.K.), Burlington, Massachusetts
| | - J P Karis
- Gainesville, Florida; Barrow Neurological Institute (Z.L., A.G.A., N.R.Z., J.P.K.)
| | - J B Andre
- University of Washington (J.B.A.), Seattle, Washington
| | - J H Miller
- Rochester, Minnesota; Phoenix Children's Hospital (R.K.R., M.T., H.H.H., J.H.M.)
| | - N K Pinter
- Phoenix, Arizona; DENT Neurologic Institute (N.K.P.)
| | - J G Pipe
- Phoenix, Arizona; Mayo Clinic (D.W., J.G.P.)
| |
Collapse
|
35
|
Abstract
MRI is a commonly used diagnostic tool in neurology, and all neurologists should possess a working knowledge of imaging fundamentals. An overview of current and impending MRI techniques is presented to help the referring clinician communicate better with the imaging department, understand the utility and limitations of current and emerging technology, improve specificity and appropriateness when ordering MRI studies, and recognize key findings.
Collapse
Affiliation(s)
- Nandor K Pinter
- Dent Neurologic Institute, 3980A Sheridan Drive, Suite 101, Amherst, NY 14226, USA; Department of Neurosurgery, State University of New York at Buffalo, Buffalo, NY, USA
| | - Joseph V Fritz
- Dent Neurologic Institute, 3980 Sheridan Drive, Suite 501, Amherst, NY 14226, USA; NeuroNetPro, Amherst, NY, USA.
| |
Collapse
|
36
|
Greve T, Sollmann N, Hock A, Hey S, Gnanaprakasam V, Nijenhuis M, Zimmer C, Kirschke JS. Highly accelerated time-of-flight magnetic resonance angiography using spiral imaging improves conspicuity of intracranial arterial branches while reducing scan time. Eur Radiol 2019; 30:855-865. [DOI: 10.1007/s00330-019-06442-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/09/2019] [Accepted: 09/09/2019] [Indexed: 12/14/2022]
|
37
|
Sun C, Yang Y, Cai X, Salerno M, Meyer CH, Weller D, Epstein FH. Non-Cartesian slice-GRAPPA and slice-SPIRiT reconstruction methods for multiband spiral cardiac MRI. Magn Reson Med 2019; 83:1235-1249. [PMID: 31565819 DOI: 10.1002/mrm.28002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 08/28/2019] [Accepted: 08/29/2019] [Indexed: 12/25/2022]
Abstract
PURPOSE Spiral MRI has advantages for cardiac imaging, and multiband (MB) spiral MRI of the heart shows promise. However, current reconstruction methods for MB spiral imaging have limitations. We sought to develop improved reconstruction methods for MB spiral cardiac MRI. METHODS Two reconstruction methods were developed. The first is non-Cartesian slice-GRAPPA (NCSG), which uses phase demodulation and gridding operations before application of a Cartesian slice-separating kernel. The second method, slice-SPIRiT, formulates the reconstruction as a minimization problem that enforces in-plane coil consistency and consistency with the acquired MB data, and uses through-plane coil sensitivity information in the iterative solution. These methods were compared with conjugate-gradient SENSE in phantoms and volunteers. Temporal alternation of CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration) phase and the use of a temporal filter were also investigated. RESULTS Phantom experiments with 3 simultaneous slices (MB = 3) showed that mean artifact power was highest for conjugate-gradient SENSE, lower for NCSG, and lowest for slice-SPIRiT. For volunteer cine imaging (MB = 3, N = 5), the artifact power was 0.182 ± 0.037, 0.148 ± 0.036, and 0.139 ± 0.034 for conjugate-gradient SENSE, NCSG, and slice-SPIRiT, respectively (P < .05, analysis of variance). Temporal alternation of CAIPIRINHA reduced artifacts for both NCSG and slice-SPIRiT. CONCLUSION The NCSG and slice-SPIRiT methods provide more accurate reconstructions for MB spiral cine imaging compared with conjugate-gradient SENSE. These methods hold promise for non-Cartesian MB imaging.
Collapse
Affiliation(s)
- Changyu Sun
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - Yang Yang
- Department of Medicine, University of Virginia Health System, Charlottesville, Virginia.,Translational and Molecular Imaging Institute and Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Xiaoying Cai
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.,Siemens Medical Solutions USA, Boston, Massachusetts
| | - Michael Salerno
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.,Department of Medicine, University of Virginia Health System, Charlottesville, Virginia.,Department of Radiology, University of Virginia Health System, Charlottesville, Virginia
| | - Craig H Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.,Department of Radiology, University of Virginia Health System, Charlottesville, Virginia
| | - Daniel Weller
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.,Department of Radiology, University of Virginia Health System, Charlottesville, Virginia.,Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia
| | - Frederick H Epstein
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.,Department of Radiology, University of Virginia Health System, Charlottesville, Virginia
| |
Collapse
|
38
|
Rahmer J, Mazurkewitz P, Börnert P, Nielsen T. Rapid acquisition of the 3D MRI gradient impulse response function using a simple phantom measurement. Magn Reson Med 2019; 82:2146-2159. [PMID: 31321818 DOI: 10.1002/mrm.27902] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 06/18/2019] [Accepted: 06/18/2019] [Indexed: 12/25/2022]
Abstract
PURPOSE To provide a simple tool for rapid measurement of the 3D gradient modulation transfer function (GMTF) of clinical MRI systems using a phantom. Knowledge of the transfer function is useful for gradient chain characterization, system calibration, and improvement of image reconstruction results. METHODS Starting from the well-established thin slice method used for phantom-based measurement of the 1D GMTF, we add phase encoding to partition the thin slices into voxels that act as localized field probes. From the signal phase evolution measured at the 3D voxel positions, the GMTF can be derived for cross and higher order spatial terms represented by spherical harmonics up to 3rd order. RESULTS Using spherical phantoms, 16 GMTFs representing all terms up to 3rd order harmonics can be determined in a scan time of <2 min. A large voxel volume of >1 mL yields high SNR, enabling signal acquisition using the system's body coil. The method is applied for improving system calibration and for characterizing the effect of additional hardware in the bore. CONCLUSION The presented method seems well-suited for rapid measurement of the GMTF of a clinical system, as it delivers high-quality results in a short scan time.
Collapse
|
39
|
Ilovitsh A, Fite BZ, Ilovitsh T, Ferrara KW. Acoustic radiation force imaging using a single-shot spiral readout. Phys Med Biol 2019; 64:125004. [PMID: 31039549 DOI: 10.1088/1361-6560/ab1e21] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The purpose of this study is to develop and validate rapid magnetic resonance acoustic radiation force imaging (MR-ARFI) using a single shot spiral readout for focused ultrasound (FUS) guidance and for local tissue displacement measurements. A magnetic resonance guided FUS system was used to focus a 3 MHz ultrasound beam to a predetermined position. MR-ARFI was performed with a Bruker 7 T MRI using a modified single-shot spiral readout, with additional motion encoding gradients that convert local displacement into the phase image. Post processing was then used to analyze the resulting displacement and to evaluate the method's performance for the detection of tissue changes resulting from thermal ablation. The single-shot spiral readout acquires a single MR-ARFI image in one second, which is up to two orders of magnitude faster than conventional 2D spin-warp spin echo that acquires the k-space data line by line. The ARFI displacement in tissue mimicking phantoms was detected and localized with less than 5% geometric distortion. The ARFI displacement was also measured pre and post thermal ablation in an ex vivo chicken breast. For transmitted peak negative pressure of 8.6 MPa, the maximum displacement of the tissue that was ablated to 70 °C was 78% lower than the pre-ablated tissue. Since spiral readout is not prone to geometrical distortion, it is well-suited for FUS guidance, without generating undesired temperature elevation. Additionally, local displacement measurements of tissues can be performed rapidly during thermal ablation procedures and may help to assess the success of the treatment.
Collapse
Affiliation(s)
- Asaf Ilovitsh
- Department of Radiology, Stanford University, Palo Alto, CA 94305, United States of America
| | | | | | | |
Collapse
|
40
|
Zeng DY, Shaikh J, Holmes S, Brunsing RL, Pauly JM, Nishimura DG, Vasanawala SS, Cheng JY. Deep residual network for off-resonance artifact correction with application to pediatric body MRA with 3D cones. Magn Reson Med 2019; 82:1398-1411. [PMID: 31115936 DOI: 10.1002/mrm.27825] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/28/2019] [Accepted: 05/01/2019] [Indexed: 01/06/2023]
Abstract
PURPOSE To enable rapid imaging with a scan time-efficient 3D cones trajectory with a deep-learning off-resonance artifact correction technique. METHODS A residual convolutional neural network to correct off-resonance artifacts (Off-ResNet) was trained with a prospective study of pediatric MRA exams. Each exam acquired a short readout scan (1.18 ms ± 0.38) and a long readout scan (3.35 ms ± 0.74) at 3 T. Short readout scans, with longer scan times but negligible off-resonance blurring, were used as reference images and augmented with additional off-resonance for supervised training examples. Long readout scans, with greater off-resonance artifacts but shorter scan time, were corrected by autofocus and Off-ResNet and compared with short readout scans by normalized RMS error, structural similarity index, and peak SNR. Scans were also compared by scoring on 8 anatomical features by two radiologists, using analysis of variance with post hoc Tukey's test and two one-sided t-tests. Reader agreement was determined with intraclass correlation. RESULTS The total scan time for long readout scans was on average 59.3% shorter than short readout scans. Images from Off-ResNet had superior normalized RMS error, structural similarity index, and peak SNR compared with uncorrected images across ±1 kHz off-resonance (P < .01). The proposed method had superior normalized RMS error over -677 Hz to +1 kHz and superior structural similarity index and peak SNR over ±1 kHz compared with autofocus (P < .01). Radiologic scoring demonstrated that long readout scans corrected with Off-ResNet were noninferior to short readout scans (P < .05). CONCLUSION The proposed method can correct off-resonance artifacts from rapid long-readout 3D cones scans to a noninferior image quality compared with diagnostically standard short readout scans.
Collapse
Affiliation(s)
- David Y Zeng
- Department of Electrical Engineering, Stanford University, Stanford, California
| | - Jamil Shaikh
- Department of Radiology, Stanford University, Stanford, California
| | - Signy Holmes
- Department of Radiology, Stanford University, Stanford, California
| | - Ryan L Brunsing
- Department of Radiology, Stanford University, Stanford, California
| | - John M Pauly
- Department of Electrical Engineering, Stanford University, Stanford, California
| | - Dwight G Nishimura
- Department of Electrical Engineering, Stanford University, Stanford, California
| | | | - Joseph Y Cheng
- Department of Radiology, Stanford University, Stanford, California
| |
Collapse
|
41
|
Ye JC. Compressed sensing MRI: a review from signal processing perspective. BMC Biomed Eng 2019; 1:8. [PMID: 32903346 PMCID: PMC7412677 DOI: 10.1186/s42490-019-0006-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 02/04/2019] [Indexed: 11/27/2022] Open
Abstract
Magnetic resonance imaging (MRI) is an inherently slow imaging modality, since it acquires multi-dimensional k-space data through 1-D free induction decay or echo signals. This often limits the use of MRI, especially for high resolution or dynamic imaging. Accordingly, many investigators has developed various acceleration techniques to allow fast MR imaging. For the last two decades, one of the most important breakthroughs in this direction is the introduction of compressed sensing (CS) that allows accurate reconstruction from sparsely sampled k-space data. The recent FDA approval of compressed sensing products for clinical scans clearly reflect the maturity of this technology. Therefore, this paper reviews the basic idea of CS and how this technology have been evolved for various MR imaging problems.
Collapse
Affiliation(s)
- Jong Chul Ye
- Department of Bio and Brain Engineering, Korea Adv. Inst. of Science & Technology (KAIST), 291 Daehak-ro, Daejeon, Korea
| |
Collapse
|
42
|
SPARKLING: variable-density k-space filling curves for accelerated T2
*
-weighted MRI. Magn Reson Med 2019; 81:3643-3661. [DOI: 10.1002/mrm.27678] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/18/2018] [Accepted: 01/08/2019] [Indexed: 01/25/2023]
|
43
|
Akçakaya M, Moeller S, Weingärtner S, Uğurbil K. Scan-specific robust artificial-neural-networks for k-space interpolation (RAKI) reconstruction: Database-free deep learning for fast imaging. Magn Reson Med 2019; 81:439-453. [PMID: 30277269 PMCID: PMC6258345 DOI: 10.1002/mrm.27420] [Citation(s) in RCA: 188] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 04/27/2018] [Accepted: 06/02/2018] [Indexed: 01/07/2023]
Abstract
PURPOSE To develop an improved k-space reconstruction method using scan-specific deep learning that is trained on autocalibration signal (ACS) data. THEORY Robust artificial-neural-networks for k-space interpolation (RAKI) reconstruction trains convolutional neural networks on ACS data. This enables nonlinear estimation of missing k-space lines from acquired k-space data with improved noise resilience, as opposed to conventional linear k-space interpolation-based methods, such as GRAPPA, which are based on linear convolutional kernels. METHODS The training algorithm is implemented using a mean square error loss function over the target points in the ACS region, using a gradient descent algorithm. The neural network contains 3 layers of convolutional operators, with 2 of these including nonlinear activation functions. The noise performance and reconstruction quality of the RAKI method was compared with GRAPPA in phantom, as well as in neurological and cardiac in vivo data sets. RESULTS Phantom imaging shows that the proposed RAKI method outperforms GRAPPA at high (≥4) acceleration rates, both visually and quantitatively. Quantitative cardiac imaging shows improved noise resilience at high acceleration rates (rate 4:23% and rate 5:48%) over GRAPPA. The same trend of improved noise resilience is also observed in high-resolution brain imaging at high acceleration rates. CONCLUSION The RAKI method offers a training database-free deep learning approach for MRI reconstruction, with the potential to improve many existing reconstruction approaches, and is compatible with conventional data acquisition protocols.
Collapse
Affiliation(s)
- Mehmet Akçakaya
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN
| | - Steen Moeller
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN
| | - Sebastian Weingärtner
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN
- Computer Assisted Clinical Medicine, University Medical Center Mannheim, Heidelberg University, Mannheim, Germany
| | - Kâmil Uğurbil
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN
| |
Collapse
|
44
|
Yu Z, Zhao T, Assländer J, Lattanzi R, Sodickson DK, Cloos MA. Exploring the sensitivity of magnetic resonance fingerprinting to motion. Magn Reson Imaging 2018; 54:241-248. [PMID: 30193953 PMCID: PMC6215476 DOI: 10.1016/j.mri.2018.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/01/2018] [Accepted: 09/04/2018] [Indexed: 11/19/2022]
Abstract
PURPOSE To explore the motion sensitivity of magnetic resonance fingerprinting (MRF), we performed experiments with different types of motion at various time intervals during multiple scans. Additionally, we investigated the possibility to correct the motion artifacts based on redundancy in MRF data. METHODS A radial version of the FISP-MRF sequence was used to acquire one transverse slice through the brain. Three subjects were instructed to move in different patterns (in-plane rotation, through-plane wiggle, complex movements, adjust head position, and pretend itch) during different time intervals. The potential to correct motion artifacts in MRF by removing motion-corrupted data points from the fingerprints and dictionary was evaluated. RESULTS Morphological structures were well preserved in multi-parametric maps despite subject motion. Although the bulk T1 values were not significantly affected by motion, fine structures were blurred when in-plane motion was present during the first part of the scan. On the other hand, T2 values showed a considerable deviation from the motion-free results, especially when through-plane motion was present in the middle of the scan (-44% on average). Explicitly removing the motion-corrupted data from the scan partially restored the T2 values (-10% on average). CONCLUSION Our experimental results showed that different kinds of motion have distinct effects on the precision and effective resolution of the parametric maps measured with MRF. Although MRF-based acquisitions can be relatively robust to motion effects occurring at the beginning or end of the sequence, relying on redundancy in the data alone is not sufficient to assure the accuracy of the multi-parametric maps in all cases.
Collapse
Affiliation(s)
- Zidan Yu
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA.
| | - Tiejun Zhao
- Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; Siemens Medical Solutions USA Inc., 40 Liberty Boulevard, Malvern, PA 19355, USA
| | - Jakob Assländer
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Riccardo Lattanzi
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| | - Daniel K Sodickson
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| | - Martijn A Cloos
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| |
Collapse
|
45
|
Malavé MO, Baron CA, Addy NO, Cheng JY, Yang PC, Hu BS, Nishimura DG. Whole-heart coronary MR angiography using a 3D cones phyllotaxis trajectory. Magn Reson Med 2018; 81:1092-1103. [PMID: 30370941 DOI: 10.1002/mrm.27475] [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: 12/04/2017] [Revised: 07/08/2018] [Accepted: 07/10/2018] [Indexed: 01/28/2023]
Abstract
PURPOSE To develop a 3D cones steady-state free precession sequence with improved robustness to respiratory motion while mitigating eddy current artifacts for free-breathing whole-heart coronary magnetic resonance angiography. METHOD The proposed sequence collects cone interleaves using a phyllotaxis pattern, which allows for more distributed k-space sampling for each heartbeat compared to a typical sequential collection pattern. A Fibonacci number of segments is chosen to minimize eddy current effects with the trade-off of an increased number of acquisition heartbeats. For verification, phyllotaxis-cones is compared to sequential-cones through simulations, phantom studies, and in vivo coronary scans with 8 subjects using 2D image-based navigators for retrospective motion correction. RESULTS Simulated point spread functions and moving phantom results show less coherent motion artifacts for phyllotaxis-cones compared to sequential-cones. Assessment of the right and left coronary arteries using reader scores and the image edge profile acutance vessel sharpness metric indicate superior image quality and sharpness for phyllotaxis-cones. CONCLUSION Phyllotaxis 3D cones results in improved qualitative image scores and coronary vessel sharpness for free-breathing whole-heart coronary magnetic resonance angiography compared to standard sequential ordering when using a steady-state free precession sequence.
Collapse
Affiliation(s)
- Mario O Malavé
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Corey A Baron
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Nii Okai Addy
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Joseph Y Cheng
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California.,Department of Radiology, Stanford University, Palo Alto, California
| | - Phillip C Yang
- Cardiovascular Medicine, Stanford University, Stanford, California
| | - Bob S Hu
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California.,Cardiology, Palo Alto Medical Foundation, Palo Alto, California
| | - Dwight G Nishimura
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| |
Collapse
|
46
|
Wallace TE, Afacan O, Waszak M, Kober T, Warfield SK. Head motion measurement and correction using FID navigators. Magn Reson Med 2018; 81:258-274. [PMID: 30058216 DOI: 10.1002/mrm.27381] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/18/2018] [Accepted: 05/08/2018] [Indexed: 11/09/2022]
Abstract
PURPOSE To develop a novel framework for rapid, intrinsic head motion measurement in MRI using FID navigators (FIDnavs) from a multichannel head coil array. METHODS FIDnavs encode substantial rigid-body motion information; however, current implementations require patient-specific training with external tracking data to extract quantitative positional changes. In this work, a forward model of FIDnav signals was calibrated using simulated movement of a reference image within a model of the spatial coil sensitivities. A FIDnav module was inserted into a nonselective 3D FLASH sequence, and rigid-body motion parameters were retrospectively estimated every readout time using nonlinear optimization to solve the inverse problem posed by the measured FIDnavs. This approach was tested in simulated data and in 7 volunteers, scanned at 3T with a 32-channel head coil array, performing a series of directed motion paradigms. RESULTS FIDnav motion estimates achieved mean absolute errors of 0.34 ± 0.49 mm and 0.52 ± 0.61° across all subjects and scans, relative to ground-truth motion measurements provided by an electromagnetic tracking system. Retrospective correction with FIDnav motion estimates resulted in substantial improvements in quantitative image quality metrics across all scans with intentional head motion. CONCLUSIONS Quantitative rigid-body motion information can be effectively estimated using the proposed FIDnav-based approach, which represents a practical method for retrospective motion compensation in less cooperative patient populations.
Collapse
Affiliation(s)
- Tess E Wallace
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Onur Afacan
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Maryna Waszak
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland.,Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.,LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Tobias Kober
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland.,Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.,LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Simon K Warfield
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
47
|
Lim Y, Lingala SG, Narayanan SS, Nayak KS. Dynamic off-resonance correction for spiral real-time MRI of speech. Magn Reson Med 2018; 81:234-246. [PMID: 30058147 DOI: 10.1002/mrm.27373] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 05/01/2018] [Accepted: 05/02/2018] [Indexed: 02/03/2023]
Abstract
PURPOSE To improve the depiction and tracking of vocal tract articulators in spiral real-time MRI (RT-MRI) of speech production by estimating and correcting for dynamic changes in off-resonance. METHODS The proposed method computes a dynamic field map from the phase of single-TE dynamic images after a coil phase compensation where complex coil sensitivity maps are estimated from the single-TE dynamic scan itself. This method is tested using simulations and in vivo data. The depiction of air-tissue boundaries is evaluated quantitatively using a sharpness metric and visual inspection. RESULTS Simulations demonstrate that the proposed method provides robust off-resonance correction for spiral readout durations up to 5 ms at 1.5T. In -vivo experiments during human speech production demonstrate that image sharpness is improved in a majority of data sets at air-tissue boundaries including the upper lip, hard palate, soft palate, and tongue boundaries, whereas the lower lip shows little improvement in the edge sharpness after correction. CONCLUSION Dynamic off-resonance correction is feasible from single-TE spiral RT-MRI data, and provides a practical performance improvement in articulator sharpness when applied to speech production imaging.
Collapse
Affiliation(s)
- Yongwan Lim
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California
| | - Sajan Goud Lingala
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California
| | - Shrikanth S Narayanan
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California
| | - Krishna S Nayak
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California
| |
Collapse
|
48
|
Cha MJ, Park HJ, Paek MY, Stemmer A, Lee ES, Park SB, Kim YS. Free-breathing ultrashort echo time lung magnetic resonance imaging using stack-of-spirals acquisition: A feasibility study in oncology patients. Magn Reson Imaging 2018; 51:137-143. [PMID: 29775663 DOI: 10.1016/j.mri.2018.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 12/30/2022]
Abstract
OBJECTIVES To investigate the diagnostic accuracy of lung magnetic resonance imaging (MRI) with a free-breathing three-dimensional ultrashort echo time spoiled gradient echo sequence using a stack-of-spirals acquisition (spiral 3D UTE) for pulmonary nodule detection at 3 T in oncology patients. METHODS The institutional review board approved this retrospective study. Between June and September of 2017, 32 oncology patients underwent both free-breathing spiral 3D UTE of the lungs and thin-section chest computed tomography (CT) for pulmonary metastasis workups. Semiquantitative analyses of the visible pulmonary vessels, bronchi, mediastinum, and overall image quality on spiral 3D UTE were assessed by two reviewers; CT was used as the reference standard. The probability of nodule presence also was assessed. RESULTS The mean acquisition duration of the spiral 3D UTE was 327 s (range, 300-465 s). The pulmonary vessels and bronchi were visible nearly consistently up to the sub-sub-segmental branch levels on spiral 3D UTE (96.9% [31/32] and 90.6% [29/32], respectively). >90% of the spiral 3D UTE images had an acceptable or good mediastinal evaluation; >80% had good or excellent overall image quality. Fifty nodules (6.1 ± 5.9 mm) were identified in 13 patients on CT; the overall nodule detection rate of spiral 3D UTE was 86% (43/50). All 20 nodules ≥ 5 mm in diameter were identified on spiral 3D UTE (100%). CONCLUSIONS Free-breathing spiral 3D UTE had high sensitivity for the detection of pulmonary nodules, a reasonable scan duration, and acceptable image quality, which may make it a potential alternative to CT for oncology patients.
Collapse
Affiliation(s)
- Min Jae Cha
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Hyun Jeong Park
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
| | | | | | - Eun Sun Lee
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Sung Bin Park
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Yang Soo Kim
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| |
Collapse
|
49
|
MRI-Based Assessment of Lower-Extremity Muscle Volumes in Patients Before and After ACL Reconstruction. J Sport Rehabil 2018; 27:201-212. [DOI: 10.1123/jsr.2016-0141] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Context:Study of muscle volumes in patients after anterior cruciate ligament (ACL) injury and reconstruction (ACL-R) is largely limited to cross-sectional assessment of the thigh musculature, which may inadequately describe posttraumatic and postsurgical muscle function. No studies have prospectively examined the influence of ACL injury and reconstruction on lower-extremity muscle volumes.Objective:Assess magnetic resonance imaging-derived lower-extremity muscle volumes, and quantify quadriceps strength and activation in patients following ACL injury and reconstruction.Design:Prospective case series.Setting:Research laboratory and magnetic resonance imaging facility.Patients (or Other Participants):Four patients (2 men and 2 women; age = 27.4 (7.4) y, height = 169.2 (8.1) cm, and mass = 74.3 (18.5) kg) scheduled for ACL-R.Intervention(s):Thirty-five muscle volumes were obtained from a bilateral lower-extremity magnetic resonance imaging before and after ACL-R.Main Outcome Measures:Muscle volumes expressed relative to (1) a normative database presurgery and postsurgery, (2) limb symmetry presurgery and postsurgery, and (3) percentage change presurgery to postsurgery. Quadriceps function was quantified by normalized knee extension maximal voluntary isometric contraction torque and central activation ratio.Results:Involved vastus lateralis and tibialis anterior were consistently smaller than healthy individuals (z < −1 SD) presurgery and postsurgery in all patients. Involved rectus femoris and vastus lateralis were more than 15% smaller than the contralateral limb presurgery, whereas the involved rectus femoris, gracilis, vastus medialis, vastus intermedius, and vastus lateralis muscle volumes exceeded 20% asymmetry postoperatively. Involved gracilis and semitendinosus atrophied more than 30% from presurgery to postsurgery. Involved maximal voluntary isometric contraction torque and central activation ratio increased by 12.7% and 12.5%, respectively, yet strength remained 33.2% asymmetric postsurgery.Conclusions:Adaptations in lower-extremity muscle volumes are present following ACL injury and reconstruction. Anterior thigh and shank muscles were smaller than healthy individuals, and large asymmetries in quadriceps volumes were observed presurgery and postsurgery. Selective atrophy of the semitendinosus and gracilis occurred following surgery. Volumetric deficits of the quadriceps musculature may exist despite improvements in muscle strength and activation.
Collapse
|
50
|
Engel M, Kasper L, Barmet C, Schmid T, Vionnet L, Wilm B, Pruessmann KP. Single‐shot spiral imaging at 7
T. Magn Reson Med 2018; 80:1836-1846. [DOI: 10.1002/mrm.27176] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/15/2018] [Accepted: 02/18/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Maria Engel
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
| | - Lars Kasper
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
- Translational Neuromodeling Unit, Institute for Biomedical EngineeringUniversity of Zurich and ETH ZurichZurich Switzerland
| | - Christoph Barmet
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
- Skope Magnetic Resonance Technologies AGZurich Switzerland
| | - Thomas Schmid
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
| | - Laetitia Vionnet
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
| | - Bertram Wilm
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
- Skope Magnetic Resonance Technologies AGZurich Switzerland
| | - Klaas P. Pruessmann
- Institute for Biomedical EngineeringETH Zurich and University of ZurichZurich Switzerland
| |
Collapse
|