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Stokes AM, Ragunathan S, Robison RK, Fuentes A, Bell LC, Karis JP, Pipe JG, Quarles CC. Development of a spiral spin- and gradient-echo (spiral-SAGE) approach for improved multi-parametric dynamic contrast neuroimaging. Magn Reson Med 2021; 86:3082-3095. [PMID: 34288112 DOI: 10.1002/mrm.28933] [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: 02/18/2021] [Revised: 06/29/2021] [Accepted: 06/30/2021] [Indexed: 11/09/2022]
Abstract
PURPOSE The purpose of this study was to develop a spiral-based combined spin- and gradient-echo (spiral-SAGE) method for simultaneous dynamic contrast-enhanced (DCE-MRI) and dynamic susceptibility contrast MRI (DSC-MRI). METHODS Using this sequence, we obtained gradient-echo TEs of 1.69 and 26 ms, a SE TE of 87.72 ms, with a TR of 1663 ms. Using an iterative SENSE reconstruction followed by deblurring, spiral-induced image artifacts were minimized. Healthy volunteer images are shown to demonstrate image quality using the optimized reconstruction, as well as for comparison with EPI-based SAGE. A bioreactor phantom was used to compare dynamic-contrast time courses with both spiral-SAGE and EPI-SAGE. A proof-of-concept cohort of patients with brain tumors shows the range of hemodynamic maps available using spiral-SAGE. RESULTS Comparison of spiral-SAGE images with conventional EPI-SAGE images illustrates substantial reductions of image distortion and artifactual image intensity variations. Bioreactor phantom data show similar dynamic contrast time courses between standard EPI-SAGE and spiral-SAGE for the second and third echoes, whereas first-echo data show improvements in quantifying T1 changes with shorter echo times. In a cohort of patients with brain tumors, spiral-SAGE-based perfusion and permeability maps are shown with comparison with the standard single-echo EPI perfusion map. CONCLUSION Spiral-SAGE provides a substantial improvement for the assessment of perfusion and permeability by mitigating artifacts typically encountered with EPI and by providing a shorter echo time for improved characterization of permeability. Spiral-SAGE enables quantification of perfusion, permeability, and vessel architectural parameters, as demonstrated in brain tumors.
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Affiliation(s)
- Ashley M Stokes
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Sudarshan Ragunathan
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Ryan K Robison
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA.,Philips Healthcare, Nashville, Tennessee, USA.,Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alberto Fuentes
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Laura C Bell
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - John P Karis
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA.,Neuroradiology, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - James G Pipe
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA.,Mayo Clinic, Rochester, Minnesota, USA
| | - C Chad Quarles
- Barrow Neuroimaging Innovation Center, Barrow Neurological Institute, Phoenix, Arizona, USA
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2
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Guo S, Fessler JA, Noll DC. High-Resolution Oscillating Steady-State fMRI Using Patch-Tensor Low-Rank Reconstruction. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:4357-4368. [PMID: 32809938 PMCID: PMC7751316 DOI: 10.1109/tmi.2020.3017450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The goals of fMRI acquisition include high spatial and temporal resolutions with a high signal to noise ratio (SNR). Oscillating Steady-State Imaging (OSSI) is a new fMRI acquisition method that provides large oscillating signals with the potential for high SNR, but does so at the expense of spatial and temporal resolutions. The unique oscillation pattern of OSSI images makes it well suited for high-dimensional modeling. We propose a patch-tensor low-rank model to exploit the local spatial-temporal low-rankness of OSSI images. We also develop a practical sparse sampling scheme with improved sampling incoherence for OSSI. With an alternating direction method of multipliers (ADMM) based algorithm, we improve OSSI spatial and temporal resolutions with a factor of 12 acquisition acceleration and 1.3 mm isotropic spatial resolution in prospectively undersampled experiments. The proposed model yields high temporal SNR with more activation than other low-rank methods. Compared to the standard grad- ient echo (GRE) imaging with the same spatial-temporal resolution, 3D OSSI tensor model reconstruction demonstrates 2 times higher temporal SNR with 2 times more functional activation.
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Zitzelsberger T, Krumm P, Hornung A, Kramer U, Nikolaou K, Schäfer JF, Schick F, Sieverding L, Martirosian P. Multi-phase coronary magnetic resonance angiography improves delineation of coronary arteries. Acta Radiol 2019; 60:1422-1429. [PMID: 30799635 DOI: 10.1177/0284185119830289] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Tanja Zitzelsberger
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Germany
| | - Patrick Krumm
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Germany
| | - Andreas Hornung
- Department of Pediatric Cardiology, University of Tuebingen, Germany
| | - Ulrich Kramer
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Germany
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Germany
| | - Jürgen F Schäfer
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Germany
| | - Fritz Schick
- Department of Diagnostic and Interventional Radiology, Section on Experimental Radiology, University of Tuebingen, Germany
| | - Ludger Sieverding
- Department of Pediatric Cardiology, University of Tuebingen, Germany
| | - Petros Martirosian
- Department of Diagnostic and Interventional Radiology, Section on Experimental Radiology, University of Tuebingen, Germany
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Shimron E, Webb AG, Azhari H. CORE-PI: Non-iterative convolution-based reconstruction for parallel MRI in the wavelet domain. Med Phys 2018; 46:199-214. [DOI: 10.1002/mp.13260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 09/17/2018] [Accepted: 10/09/2018] [Indexed: 01/08/2023] Open
Affiliation(s)
- Efrat Shimron
- Department of Biomedical Engineering; Technion - Israel Institute of Technology; Haifa 3200003 Israel
| | - Andrew G. Webb
- C.J. Gorter Center for High Field MRI; Department of Radiology; Leiden University Medical Center; Albinusdreef 2 2333 ZA Leiden The Netherlands
| | - Haim Azhari
- Department of Biomedical Engineering; Technion - Israel Institute of Technology; Haifa 3200003 Israel
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Iyama Y, Nakaura T, Nagayama Y, Oda S, Utsunomiya D, Kidoh M, Yuki H, Hirata K, Namimoto T, Kitajima M, Morita K, Funama Y, Takemura A, Okuaki T, Yamashita Y. Single-Breath-Hold Whole-heart Unenhanced Coronary MRA Using Multi-shot Gradient Echo EPI at 3T: Comparison with Free-breathing Turbo-field-echo Coronary MRA on Healthy Volunteers. Magn Reson Med Sci 2017; 17:161-167. [PMID: 28652524 PMCID: PMC5891342 DOI: 10.2463/mrms.mp.2017-0037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Purpose: We investigated the feasibility of single breath hold unenhanced coronary MRA using multi-shot gradient echo planar imaging (MSG-EPI) on a 3T-scanner. Methods: Fourteen volunteers underwent single breath hold coronary MRA with a MSG-EPI and free-breathing turbo field echo (TFE) coronary MRA at 3T. The acquisition time, signal to noise ratio (SNR), and the contrast of the sequences were compared with the paired t-test. Readers evaluated the image contrast, noise, sharpness, artifacts, and the overall image quality. Results: The acquisition time was 88.1% shorter for MSG-EPI than TFE (24.7 ± 2.5 vs 206.4 ± 23.1 sec, P < 0.01). The SNR was significantly higher on MSG-EPI than TFE scans (P < 0.01). There was no significant difference in the contrast on MSG-EPI and TFE scans (1.8 ± 0.3 vs 1.9 ± 0.3, P = 0.24). There was no significant difference in image contrast, image sharpness, and overall image quality between two scan techniques. The score of image noise and artifact were significantly higher on MSG-EPI than TFE scans (P < 0.05). Conclusion: The single breath hold MSG-EPI sequence is a promising technique for shortening the scan time and for preserving the image quality of unenhanced whole heart coronary MRA on a 3T scanner.
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Affiliation(s)
- Yuji Iyama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Yasunori Nagayama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Seitaro Oda
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Daisuke Utsunomiya
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Hideaki Yuki
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Kenichiro Hirata
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Tomohiro Namimoto
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Mika Kitajima
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Kosuke Morita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University
| | | | | | - Yasuyuki Yamashita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
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Choi J, Kim H. Implementation of time-efficient adaptive sampling function design for improved undersampled MRI reconstruction. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 273:47-55. [PMID: 27744148 DOI: 10.1016/j.jmr.2016.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 06/06/2023]
Abstract
To improve the efficacy of undersampled MRI, a method of designing adaptive sampling functions is proposed that is simple to implement on an MR scanner and yet effectively improves the performance of the sampling functions. An approximation of the energy distribution of an image (E-map) is estimated from highly undersampled k-space data acquired in a prescan and efficiently recycled in the main scan. An adaptive probability density function (PDF) is generated by combining the E-map with a modeled PDF. A set of candidate sampling functions are then prepared from the adaptive PDF, among which the one with maximum energy is selected as the final sampling function. To validate its computational efficiency, the proposed method was implemented on an MR scanner, and its robust performance in Fourier-transform (FT) MRI and compressed sensing (CS) MRI was tested by simulations and in a cherry tomato. The proposed method consistently outperforms the conventional modeled PDF approach for undersampling ratios of 0.2 or higher in both FT-MRI and CS-MRI. To fully benefit from undersampled MRI, it is preferable that the design of adaptive sampling functions be performed online immediately before the main scan. In this way, the proposed method may further improve the efficacy of the undersampled MRI.
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Affiliation(s)
- Jinhyeok Choi
- Department of Biomedical Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hyeonjin Kim
- Department of Biomedical Sciences, Seoul National University, Seoul, Republic of Korea; Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea.
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Kustner T, Wurslin C, Gatidis S, Martirosian P, Nikolaou K, Schwenzer NF, Schick F, Yang B, Schmidt H. MR Image Reconstruction Using a Combination of Compressed Sensing and Partial Fourier Acquisition: ESPReSSo. IEEE TRANSACTIONS ON MEDICAL IMAGING 2016; 35:2447-2458. [PMID: 27295659 DOI: 10.1109/tmi.2016.2577642] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A Cartesian subsampling scheme is proposed incorporating the idea of PF acquisition and variable-density Poisson Disc (vdPD) subsampling by redistributing the sampling space onto a smaller region aiming to increase k-space sampling density for a given acceleration factor. Especially the normally sparse sampled high-frequency components benefit from this sampling redistribution, leading to improved edge delineation. The prospective subsampled and compacted k-space can be reconstructed by a seamless combination of a CS-algorithm with a Hermitian symmetry constraint accounting for the missing part of the k-space. This subsampling and reconstruction scheme is called Compressed Sensing Partial Subsampling (ESPReSSo) and was tested on in-vivo abdominal MRI datasets. Different reconstruction methods and regularizations are investigated and analyzed via global (intensity-based) and local (region-of-interest and line evaluation) image metrics, to conclude a clinical feasible setup. Results substantiate that ESPReSSo can provide improved edge delineation and regional homogeneity for multidimensional and multi-coil MRI datasets and is therefore useful in applications depending on well-defined tissue boundaries, such as image registration and segmentation or detection of small lesions in clinical diagnostics.
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Sparse Parallel MRI Based on Accelerated Operator Splitting Schemes. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:1724630. [PMID: 27746824 PMCID: PMC5056009 DOI: 10.1155/2016/1724630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/29/2016] [Indexed: 11/17/2022]
Abstract
Recently, the sparsity which is implicit in MR images has been successfully exploited for fast MR imaging with incomplete acquisitions. In this paper, two novel algorithms are proposed to solve the sparse parallel MR imaging problem, which consists of l1 regularization and fidelity terms. The two algorithms combine forward-backward operator splitting and Barzilai-Borwein schemes. Theoretically, the presented algorithms overcome the nondifferentiable property in l1 regularization term. Meanwhile, they are able to treat a general matrix operator that may not be diagonalized by fast Fourier transform and to ensure that a well-conditioned optimization system of equations is simply solved. In addition, we build connections between the proposed algorithms and the state-of-the-art existing methods and prove their convergence with a constant stepsize in Appendix. Numerical results and comparisons with the advanced methods demonstrate the efficiency of proposed algorithms.
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Li Y, Yang R, Zhang C, Zhang J, Jia S, Zhou Z. Analysis of generalized rosette trajectory for compressed sensing MRI. Med Phys 2016; 42:5530-44. [PMID: 26329000 DOI: 10.1118/1.4928152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The application of compressed sensing (CS) technology in magnetic resonance imaging (MRI) is to accelerate the MRI scan speed by incoherent undersampling of k-space data and nonlinear iterative reconstruction of MRI images. This paper generalizes the existing rosette trajectories to configure the sampling patterns for undersampled k-space data acquisition in MRI scans. The arch and curvature characteristics of the generalized rosette trajectories are analyzed to explore their feasibility and advantages for CS reconstruction of MRI images. METHODS Two key properties crucial to the CS MRI application, the scan speed and sampling incoherence of the generalized rosette trajectories, are analyzed. The analysis on the scan speed of generalized rosette trajectories is based on the transversal time derived from the curvature of the trajectories, and the sampling incoherence is based on the evaluation of the point spread function for the measurement matrix. The results of analysis are supported by extensive simulations where the performances of rosette, spiral, and radial sampling patterns at different acceleration factors are compared. RESULTS It is shown that compared with spiral trajectories, the arch and curvature characteristics of the generalized rosette trajectories are more feasible to meet the physical requirements of undersampled k-space data acquisition in terms of time shortness and scan area. It is further shown that the sampling pattern of the rosette trajectory has higher incoherence than that of the other trajectories and can thus achieve higher reconstruction performance. Reconstruction performances illustrate that the rosette trajectory can achieve about 10% higher peak signal-to-noise ratio than radial and spiral trajectories under the high acceleration factor R = 10. CONCLUSIONS The generalized rosette trajectories can be a desirable candidate for CS reconstruction of MRI.
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Affiliation(s)
- Ya Li
- School of Information Science and Technology, Sun Yat-sen University, Guangzhou 510009, China
| | - Ran Yang
- School of Mobile Information Engineering, Sun Yat-sen University, Zhuhai 519082, China
| | - Cishen Zhang
- Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn VIC 3122, Australia
| | - Jingxin Zhang
- Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn VIC 3122, Australia and Department of Electrical and Computer Systems Engineering, Monash University, Clayton VIC 3800, Australia
| | - Sen Jia
- School of Information Science and Technology, Sun Yat-sen University, Guangzhou 510009, China
| | - Zhiyang Zhou
- Department of Radiology, The Sixth Affiliated Hospital (Gastrointestinal Hospital), Sun Yat-sen University, Guangzhou 510655, China
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10
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Fang S, Li L, Wu W, Wei J, Zhang B, Kim DH, Yuan C, Guo H. Multiscale coherence regularization reconstruction using a nonlocal operator for fast variable-density spiral imaging. Magn Reson Imaging 2016; 34:964-73. [PMID: 27108356 DOI: 10.1016/j.mri.2016.04.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 04/06/2016] [Accepted: 04/17/2016] [Indexed: 11/17/2022]
Abstract
PURPOSE Nonlinear reconstruction can suppress pseudo-incoherent aliasing artifacts from variable-density spiral (VDS) trajectories when interleaves are undersampled for acquisition acceleration during MR imaging. However, large-scale aliasing artifact suppression often conflicts with fine-scale structure preservation and may cause deterioration of image quality in the reconstructed images. To address this issue, a sequential, multiscale coherence regularization algorithm using a nonlocal operator (mCORNOL) is proposed. METHODS mCORNOL is formed by exploiting the scale-control capacity of nonlocal operators in image structure measurement. By changing the scale of the structure measurement, the smoothing constraint scales can be adjusted. Starting with a large value, mCORNOL gradually reduces the smoothing constraint scale until it reaches the same level as the noise. Therefore, the large-scale smoothing constraint dominates the first few iterations of the reconstruction and removes aliasing artifacts as well as fine structures. In the following iterations, the smoothing constraint is restricted to a smaller and smaller scale, so the fidelity term progressively dominates and restores lost structures. Thus, aliasing artifact removal and structure preservation can be decoupled and achieved sequentially, which alleviates the conflicts between them. RESULTS Numerical simulation and in vivo experiment results demonstrate the superiority of mCORNOL for aliasing artifact suppression and image structure preservation at high reduction factors, compared to SENSE, Total Variation and the original CORNOL reconstruction. CONCLUSIONS mCORNOL reconstruction provides an effective way to improve image quality for undersampled VDS acquisitions.
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Affiliation(s)
- Sheng Fang
- Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University
| | - Lyu Li
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Wenchuan Wu
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China
| | - Juan Wei
- Philips Research Asia, Shanghai, China
| | | | - Dong-Hyun Kim
- Department of Electrical and Electronic Engineering, Yonsei University, Seoul, Korea
| | - Chun Yuan
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China; Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Hua Guo
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China.
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Edelman RR, Giri S, Pursnani A, Botelho MPF, Li W, Koktzoglou I. Breath-hold imaging of the coronary arteries using Quiescent-Interval Slice-Selective (QISS) magnetic resonance angiography: pilot study at 1.5 Tesla and 3 Tesla. J Cardiovasc Magn Reson 2015; 17:101. [PMID: 26597281 PMCID: PMC4655490 DOI: 10.1186/s12968-015-0205-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/15/2015] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Coronary magnetic resonance angiography (MRA) is usually obtained with a free-breathing navigator-gated 3D acquisition. Our aim was to develop an alternative breath-hold approach that would allow the coronary arteries to be evaluated in a much shorter time and without risk of degradation by respiratory motion artifacts. For this purpose, we implemented a breath-hold, non-contrast-enhanced, quiescent-interval slice-selective (QISS) 2D technique. Sequence performance was compared at 1.5 and 3 Tesla using both radial and Cartesian k-space trajectories. METHODS The left coronary circulation was imaged in six healthy subjects and two patients with coronary artery disease. Breath-hold QISS was compared with T2-prepared 2D balanced steady-state free-precession (bSSFP) and free-breathing, navigator-gated 3D bSSFP. RESULTS Approximately 10 2.1-mm thick slices were acquired in a single ~20-s breath-hold using two-shot QISS. QISS contrast-to-noise ratio (CNR) was 1.5-fold higher at 3 Tesla than at 1.5 Tesla. Cartesian QISS provided the best coronary-to-myocardium CNR, whereas radial QISS provided the sharpest coronary images. QISS image quality exceeded that of free-breathing 3D coronary MRA with few artifacts at either field strength. Compared with T2-prepared 2D bSSFP, multi-slice capability was not restricted by the specific absorption rate at 3 Tesla and pericardial fluid signal was better suppressed. In addition to depicting the coronary arteries, QISS could image intra-cardiac structures, pericardium, and the aortic root in arbitrary slice orientations. CONCLUSIONS Breath-hold QISS is a simple, versatile, and time-efficient method for coronary MRA that provides excellent image quality at both 1.5 and 3 Tesla. Image quality exceeded that of free-breathing, navigator-gated 3D MRA in a much shorter scan time. QISS also allowed rapid multi-slice bright-blood, diastolic phase imaging of the heart, which may have complementary value to multi-phase cine imaging. We conclude that, with further clinical validation, QISS might provide an efficient alternative to commonly used free-breathing coronary MRA techniques.
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Affiliation(s)
- Robert R Edelman
- Department of Radiology, NorthShore University HealthSystem, 2650 Ridge Avenue, Evanston, IL, 60201, USA.
- Feinberg School of Medicine, Northwestern University, Chicago, USA.
| | - S Giri
- Siemens Medical Solutions USA, Inc., Chicago, USA.
| | - A Pursnani
- Department of Radiology, NorthShore University HealthSystem, 2650 Ridge Avenue, Evanston, IL, 60201, USA.
- The University of Chicago Pritzker School of Medicine, Chicago, USA.
| | - M P F Botelho
- Department of Radiology, NorthShore University HealthSystem, 2650 Ridge Avenue, Evanston, IL, 60201, USA.
| | - W Li
- Department of Radiology, NorthShore University HealthSystem, 2650 Ridge Avenue, Evanston, IL, 60201, USA.
- The University of Chicago Pritzker School of Medicine, Chicago, USA.
| | - I Koktzoglou
- Department of Radiology, NorthShore University HealthSystem, 2650 Ridge Avenue, Evanston, IL, 60201, USA.
- The University of Chicago Pritzker School of Medicine, Chicago, USA.
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12
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Yang B, Yuan M, Ma Y, Zhang J, Zhan K. Local sparsity enhanced compressed sensing magnetic resonance imaging in uniform discrete curvelet domain. BMC Med Imaging 2015; 15:28. [PMID: 26253135 PMCID: PMC4528851 DOI: 10.1186/s12880-015-0065-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Accepted: 06/16/2015] [Indexed: 11/20/2022] Open
Abstract
Background Compressed sensing(CS) has been well applied to speed up imaging by exploring image sparsity over predefined basis functions or learnt dictionary. Firstly, the sparse representation is generally obtained in a single transform domain by using wavelet-like methods, which cannot produce optimal sparsity considering sparsity, data adaptivity and computational complexity. Secondly, most state-of-the-art reconstruction models seldom consider composite regularization upon the various structural features of images and transform coefficients sub-bands. Therefore, these two points lead to high sampling rates for reconstructing high-quality images. Methods In this paper, an efficient composite sparsity structure is proposed. It learns adaptive dictionary from lowpass uniform discrete curvelet transform sub-band coefficients patches. Consistent with the sparsity structure, a novel composite regularization reconstruction model is developed to improve reconstruction results from highly undersampled k-space data. It is established via minimizing spatial image and lowpass sub-band coefficients total variation regularization, transform sub-bands coefficients l1 sparse regularization and constraining k-space measurements fidelity. A new augmented Lagrangian method is then introduced to optimize the reconstruction model. It updates representation coefficients of lowpass sub-band coefficients over dictionary, transform sub-bands coefficients and k-space measurements upon the ideas of constrained split augmented Lagrangian shrinkage algorithm. Results Experimental results on in vivo data show that the proposed method obtains high-quality reconstructed images. The reconstructed images exhibit the least aliasing artifacts and reconstruction error among current CS MRI methods. Conclusions The proposed sparsity structure can fit and provide hierarchical sparsity for magnetic resonance images simultaneously, bridging the gap between predefined sparse representation methods and explicit dictionary. The new augmented Lagrangian method provides solutions fully complying to the composite regularization reconstruction model with fast convergence speed.
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Affiliation(s)
- Bingxin Yang
- School of Information Science & Engineering, Lanzhou University, Tianshui South Road No.222, Lanzhou, 730000, China.
| | - Min Yuan
- School of Information Science & Engineering, Lanzhou University, Tianshui South Road No.222, Lanzhou, 730000, China.
| | - Yide Ma
- School of Information Science & Engineering, Lanzhou University, Tianshui South Road No.222, Lanzhou, 730000, China.
| | - Jiuwen Zhang
- School of Information Science & Engineering, Lanzhou University, Tianshui South Road No.222, Lanzhou, 730000, China.
| | - Kun Zhan
- School of Information Science & Engineering, Lanzhou University, Tianshui South Road No.222, Lanzhou, 730000, China.
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Abstract
Tremendous advances have been made in abdominopelvic MR imaging, which continue to improve image quality, and make acquisitions faster and robust. We briefly discuss the role of non-Cartesian acquisition schemes as well as dual parallel radiofrequency (RF) transmit systems in the article to further improve image quality of the abdominal MR imaging. Furthermore, the use of hybrid PET/MR systems has the potential to synergistically combine MR imaging with PET acquisition, and the evolving role of hybrid PET/MR imaging is discussed.
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Affiliation(s)
- Andrea Kierans
- Department of Radiology, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
| | - Nainesh Parikh
- Department of Radiology, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
| | - Hersh Chandarana
- Department of Radiology, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA.
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14
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Whole heart coronary imaging with flexible acquisition window and trigger delay. PLoS One 2015; 10:e0112020. [PMID: 25719750 PMCID: PMC4342264 DOI: 10.1371/journal.pone.0112020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/27/2014] [Indexed: 11/18/2022] Open
Abstract
Coronary magnetic resonance imaging (MRI) requires a correctly timed trigger delay derived from a scout cine scan to synchronize k-space acquisition with the quiescent period of the cardiac cycle. However, heart rate changes between breath-held cine and free-breathing coronary imaging may result in inaccurate timing errors. Additionally, the determined trigger delay may not reflect the period of minimal motion for both left and right coronary arteries or different segments. In this work, we present a whole-heart coronary imaging approach that allows flexible selection of the trigger delay timings by performing k-space sampling over an enlarged acquisition window. Our approach addresses coronary motion in an interactive manner by allowing the operator to determine the temporal window with minimal cardiac motion for each artery region. An electrocardiogram-gated, k-space segmented 3D radial stack-of-stars sequence that employs a custom rotation angle is developed. An interactive reconstruction and visualization platform is then employed to determine the subset of the enlarged acquisition window for minimal coronary motion. Coronary MRI was acquired on eight healthy subjects (5 male, mean age = 37 ± 18 years), where an enlarged acquisition window of 166–220 ms was set 50 ms prior to the scout-derived trigger delay. Coronary visualization and sharpness scores were compared between the standard 120 ms window set at the trigger delay, and those reconstructed using a manually adjusted window. The proposed method using manual adjustment was able to recover delineation of five mid and distal right coronary artery regions that were otherwise not visible from the standard window, and the sharpness scores improved in all coronary regions using the proposed method. This paper demonstrates the feasibility of a whole-heart coronary imaging approach that allows interactive selection of any subset of the enlarged acquisition window for a tailored reconstruction for each branch region.
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Döpfert J, Witte C, Kunth M, Schröder L. Sensitivity enhancement of (Hyper-)CEST image series by exploiting redundancies in the spectral domain. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:100-7. [PMID: 24470299 DOI: 10.1002/cmmi.1543] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/13/2013] [Indexed: 02/06/2023]
Abstract
CEST has proven to be a valuable technique for the detection of hyperpolarized xenon-based functionalized contrast agents. Additional information can be encoded in the spectral dimension, allowing the simultaneous detection of multiple different biosensors. However, owing to the low concentration of dissolved xenon in biological tissue, the signal-to-noise ratio (SNR) of Hyper-CEST data is still a critical issue. In this work, we present two techniques aiming to increase SNR by exploiting the typically high redundancy in spectral CEST image series: PCA-based post-processing and sub-sampled acquisition with low-rank reconstruction. Each of them yields a significant SNR enhancement, demonstrating the feasibility of the two approaches. While the first method is directly applicable to proton CEST experiments as well, the second one is particularly beneficial when dealing with hyperpolarized nuclei, since it distributes the non-renewable initial polarization more efficiently over the sampling points. The results obtained are a further step towards the detection of xenon biosensors with spectral Hyper-CEST imaging in vivo.
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Affiliation(s)
- Jörg Döpfert
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
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Akçakaya M, Nam S, Basha TA, Kawaji K, Tarokh V, Nezafat R. An augmented Lagrangian based compressed sensing reconstruction for non-Cartesian magnetic resonance imaging without gridding and regridding at every iteration. PLoS One 2014; 9:e107107. [PMID: 25215945 PMCID: PMC4162575 DOI: 10.1371/journal.pone.0107107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 08/14/2014] [Indexed: 12/03/2022] Open
Abstract
Background Non-Cartesian trajectories are used in a variety of fast imaging applications, due to the incoherent image domain artifacts they create when undersampled. While the gridding technique is commonly utilized for reconstruction, the incoherent artifacts may be further removed using compressed sensing (CS). CS reconstruction is typically done using conjugate-gradient (CG) type algorithms, which require gridding and regridding to be performed at every iteration. This leads to a large computational overhead that hinders its applicability. Methods We sought to develop an alternative method for CS reconstruction that only requires two gridding and one regridding operation in total, irrespective of the number of iterations. This proposed technique is evaluated on phantom images and whole-heart coronary MRI acquired using 3D radial trajectories, and compared to conventional CS reconstruction using CG algorithms in terms of quantitative vessel sharpness, vessel length, computation time, and convergence rate. Results Both CS reconstructions result in similar vessel length (P = 0.30) and vessel sharpness (P = 0.62). The per-iteration complexity of the proposed technique is approximately 3-fold lower than the conventional CS reconstruction (17.55 vs. 52.48 seconds in C++). Furthermore, for in-vivo datasets, the convergence rate of the proposed technique is faster (60±13 vs. 455±320 iterations) leading to a ∼23-fold reduction in reconstruction time. Conclusions The proposed reconstruction provides images of similar quality to the conventional CS technique in terms of removing artifacts, but at a much lower computational complexity.
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Affiliation(s)
- Mehmet Akçakaya
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Seunghoon Nam
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America; Surgical Technologies, Medtronic, Inc., Littleton, Massachusetts, United States of America
| | - Tamer A Basha
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Keigo Kawaji
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America; Department of Medicine (Section of Cardiology), University of Chicago, Chicago, Illinois, United States of America
| | - Vahid Tarokh
- School of Engineering & Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
| | - Reza Nezafat
- Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
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Self-navigation with compressed sensing for 2D translational motion correction in free-breathing coronary MRI: a feasibility study. PLoS One 2014; 9:e105523. [PMID: 25171369 PMCID: PMC4149508 DOI: 10.1371/journal.pone.0105523] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 07/23/2014] [Indexed: 11/30/2022] Open
Abstract
Purpose Respiratory motion correction remains a challenge in coronary magnetic resonance imaging (MRI) and current techniques, such as navigator gating, suffer from sub-optimal scan efficiency and ease-of-use. To overcome these limitations, an image-based self-navigation technique is proposed that uses “sub-images” and compressed sensing (CS) to obtain translational motion correction in 2D. The method was preliminarily implemented as a 2D technique and tested for feasibility for targeted coronary imaging. Methods During a 2D segmented radial k-space data acquisition, heavily undersampled sub-images were reconstructed from the readouts collected during each cardiac cycle. These sub-images may then be used for respiratory self-navigation. Alternatively, a CS reconstruction may be used to create these sub-images, so as to partially compensate for the heavy undersampling. Both approaches were quantitatively assessed using simulations and in vivo studies, and the resulting self-navigation strategies were then compared to conventional navigator gating. Results Sub-images reconstructed using CS showed a lower artifact level than sub-images reconstructed without CS. As a result, the final image quality was significantly better when using CS-assisted self-navigation as opposed to the non-CS approach. Moreover, while both self-navigation techniques led to a 69% scan time reduction (as compared to navigator gating), there was no significant difference in image quality between the CS-assisted self-navigation technique and conventional navigator gating, despite the significant decrease in scan time. Conclusions CS-assisted self-navigation using 2D translational motion correction demonstrated feasibility of producing coronary MRA data with image quality comparable to that obtained with conventional navigator gating, and does so without the use of additional acquisitions or motion modeling, while still allowing for 100% scan efficiency and an improved ease-of-use. In conclusion, compressed sensing may become a critical adjunct for 2D translational motion correction in free-breathing cardiac imaging with high spatial resolution. An expansion to modern 3D approaches is now warranted.
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Oh H, Lee S. Visually weighted reconstruction of compressive sensing MRI. Magn Reson Imaging 2014; 32:270-80. [DOI: 10.1016/j.mri.2012.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 09/28/2012] [Accepted: 11/10/2012] [Indexed: 12/01/2022]
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High-resolution 3D whole-heart coronary MRA: a study on the combination of data acquisition in multiple breath-holds and 1D residual respiratory motion compensation. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2014; 27:435-43. [PMID: 24402560 DOI: 10.1007/s10334-013-0428-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 12/09/2013] [Accepted: 12/16/2013] [Indexed: 10/25/2022]
Abstract
OBJECT To study a scan protocol for coronary magnetic resonance angiography based on multiple breath-holds featuring 1D motion compensation and to compare the resulting image quality to a navigator-gated free-breathing acquisition. Image reconstruction was performed using L1 regularized iterative SENSE. MATERIALS AND METHODS The effects of respiratory motion on the Cartesian sampling scheme were minimized by performing data acquisition in multiple breath-holds. During the scan, repetitive readouts through a k-space center were used to detect and correct the respiratory displacement of the heart by exploiting the self-navigation principle in image reconstruction. In vivo experiments were performed in nine healthy volunteers and the resulting image quality was compared to a navigator-gated reference in terms of vessel length and sharpness. RESULTS Acquisition in breath-hold is an effective method to reduce the scan time by more than 30% compared to the navigator-gated reference. Although an equivalent mean image quality with respect to the reference was achieved with the proposed method, the 1D motion compensation did not work equally well in all cases. CONCLUSION In general, the image quality scaled with the robustness of the motion compensation. Nevertheless, the featured setup provides a positive basis for future extension with more advanced motion compensation methods.
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Shin T, Lustig M, Nishimura DG, Hu BS. Rapid single-breath-hold 3D late gadolinium enhancement cardiac MRI using a stack-of-spirals acquisition. J Magn Reson Imaging 2013; 40:1496-502. [PMID: 24243575 DOI: 10.1002/jmri.24494] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 10/08/2013] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop a rapid single-breath-hold 3D late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) method, and demonstrate its feasibility in cardiac patients. MATERIALS AND METHODS An inversion recovery dual-density 3D stack-of-spirals imaging sequence was developed. The spiral acquisition was 2-fold accelerated by self-consistent parallel imaging reconstruction (SPIRiT), which resulted in a total scan time of 12 heartbeats. Field map-based linear off-resonance correction was incorporated to the SPIRiT reconstruction. The 3D spiral LGE scans were performed in 15 patients who were referred for clinically ordered cardiac MR examinations that included the standard 2D multislice LGE imaging. Image sharpness and overall quality were qualitatively assessed based on 5-point scales. RESULTS Scar-induced hyper-LGE was identified in 4 out of the 15 patients by both 3D spiral and 2D multislice LGE tests. On average over all datasets (n = 15), the image sharpness scores were 3.9 (3D spiral) and 4.0 (2D multislice), and the image quality scores were 4.1 (3D spiral) and 4.0 (2D multislice) with no significant difference in both metrics (paired t-test; P > 0.1). The average scar contrast enhancement ratios were 0.72 and 0.75 in 3D and 2D images, respectively (n = 4). The average difference of fractional scar volumes measured in 3D and 2D images was 4.3% (n = 3). CONCLUSION Stack-of-spiral acquisition combined with non-Cartesian SPIRiT parallel imaging enables rapid 3D LGE MRI in a 12 heartbeat-long breath-hold.J.
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Affiliation(s)
- Taehoon Shin
- Department of Electrical Engineering, Stanford University, Stanford, California, USA
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Xu J, Kim D, Otazo R, Srichai MB, Lim RP, Axel L, Mcgorty KA, Niendorf T, Sodickson DK. Towards a five-minute comprehensive cardiac MR examination using highly accelerated parallel imaging with a 32-element coil array: feasibility and initial comparative evaluation. J Magn Reson Imaging 2013; 38:180-8. [PMID: 23197471 PMCID: PMC3615039 DOI: 10.1002/jmri.23955] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 10/11/2012] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To evaluate the feasibility and perform initial comparative evaluations of a 5-minute comprehensive whole-heart magnetic resonance imaging (MRI) protocol with four image acquisition types: perfusion (PERF), function (CINE), coronary artery imaging (CAI), and late gadolinium enhancement (LGE). MATERIALS AND METHODS This study protocol was Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board-approved. A 5-minute comprehensive whole-heart MRI examination protocol (Accelerated) using 6-8-fold-accelerated volumetric parallel imaging was incorporated into and compared with a standard 2D clinical routine protocol (Standard). Following informed consent, 20 patients were imaged with both protocols. Datasets were reviewed for image quality using a 5-point Likert scale (0 = non-diagnostic, 4 = excellent) in blinded fashion by two readers. RESULTS Good image quality with full whole-heart coverage was achieved using the accelerated protocol, particularly for CAI, although significant degradations in quality, as compared with traditional lengthy examinations, were observed for the other image types. Mean total scan time was significantly lower for the Accelerated as compared to Standard protocols (28.99 ± 4.59 min vs. 1.82 ± 0.05 min, P < 0.05). Overall image quality for the Standard vs. Accelerated protocol was 3.67 ± 0.29 vs. 1.5 ± 0.51 (P < 0.005) for PERF, 3.48 ± 0.64 vs. 2.6 ± 0.68 (P < 0.005) for CINE, 2.35 ± 1.01 vs. 2.48 ± 0.68 (P = 0.75) for CAI, and 3.67 ± 0.42 vs. 2.67 ± 0.84 (P < 0.005) for LGE. Diagnostic image quality for Standard vs. Accelerated protocols was 20/20 (100%) vs. 10/20 (50%) for PERF, 20/20 (100%) vs. 18/20 (90%) for CINE, 18/20 (90%) vs. 18/20 (90%) for CAI, and 20/20 (100%) vs. 18/20 (90%) for LGE. CONCLUSION This study demonstrates the technical feasibility and promising image quality of 5-minute comprehensive whole-heart cardiac examinations, with simplified scan prescription and high spatial and temporal resolution enabled by highly parallel imaging technology. The study also highlights technical hurdles that remain to be addressed. Although image quality remained diagnostic for most scan types, the reduced image quality of PERF, CINE, and LGE scans in the Accelerated protocol remain a concern.
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Affiliation(s)
- Jian Xu
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA
- PolyTechnic Institute of New York University, Brooklyn, New York, NY, USA
- Siemens Medical Solutions USA Inc., New York, NY, USA
| | - Daniel Kim
- Radiology, The University of Utah, Salt Lake City, Utah, USA
| | - Ricardo Otazo
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Monvadi B. Srichai
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Ruth. P. Lim
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Leon Axel
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Kelly Anne Mcgorty
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, 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
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Sarracanie M, Armstrong BD, Stockmann J, Rosen MS. High speed 3D overhauser-enhanced MRI using combined b-SSFP and compressed sensing. Magn Reson Med 2013; 71:735-45. [DOI: 10.1002/mrm.24705] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mathieu Sarracanie
- Department of Physics; Harvard University; Cambridge Massachusetts USA
- Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Boston Massachusetts USA
| | - Brandon D. Armstrong
- Department of Physics; Harvard University; Cambridge Massachusetts USA
- Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Boston Massachusetts USA
| | - Jason Stockmann
- Department of Physics; Harvard University; Cambridge Massachusetts USA
- Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Boston Massachusetts USA
| | - Matthew S. Rosen
- Department of Physics; Harvard University; Cambridge Massachusetts USA
- Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Boston Massachusetts USA
- Department of Radiology, Harvard Medical School; Boston Massachusetts USA
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Holland DJ, Liu C, Song X, Mazerolle EL, Stevens MT, Sederman AJ, Gladden LF, D'Arcy RCN, Bowen CV, Beyea SD. Compressed sensing reconstruction improves sensitivity of variable density spiral fMRI. Magn Reson Med 2013; 70:1634-43. [DOI: 10.1002/mrm.24621] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 11/30/2012] [Accepted: 12/11/2012] [Indexed: 01/25/2023]
Affiliation(s)
- D. J. Holland
- Department of Chemical Engineering and Biotechnology; University of Cambridge; Cambridge UK
| | - C. Liu
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
| | - X. Song
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
| | - E. L. Mazerolle
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
- Department of Psychology and Neuroscience; Dalhousie University; Halifax Nova Scotia Canada
| | - M. T. Stevens
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
- Department of Physics; Dalhousie University; Halifax Nova Scotia Canada
| | - A. J. Sederman
- Department of Chemical Engineering and Biotechnology; University of Cambridge; Cambridge UK
| | - L. F. Gladden
- Department of Chemical Engineering and Biotechnology; University of Cambridge; Cambridge UK
| | - R. C. N. D'Arcy
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
- Department of Psychology and Neuroscience; Dalhousie University; Halifax Nova Scotia Canada
- Department of Radiology; Dalhousie University; Halifax Nova Scotia Canada
| | - C. V. Bowen
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
- Department of Physics; Dalhousie University; Halifax Nova Scotia Canada
- Department of Radiology; Dalhousie University; Halifax Nova Scotia Canada
- School of Biomedical Engineering; Dalhousie University; Halifax Nova Scotia Canada
| | - S. D. Beyea
- Institute for Biodiagnostics (Atlantic); National Research Council Canada; Halifax Nova Scotia Canada
- Department of Physics; Dalhousie University; Halifax Nova Scotia Canada
- Department of Radiology; Dalhousie University; Halifax Nova Scotia Canada
- School of Biomedical Engineering; Dalhousie University; Halifax Nova Scotia Canada
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Zhong J, Mills PH, Hitchens TK, Ahrens ET. Accelerated fluorine-19 MRI cell tracking using compressed sensing. Magn Reson Med 2012; 69:1683-90. [PMID: 22837054 DOI: 10.1002/mrm.24414] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 06/01/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
Abstract
Cell tracking using perfluorocarbon labels and fluorine-19 (19F) MRI is a noninvasive approach to visualize and quantify cell populations in vivo. In this study, we investigated three-dimensional compressed sensing methods to accelerate 19F MRI data acquisition for cell tracking and evaluate the impact of acceleration on 19F signal quantification. We show that a greater than 8-fold reduction in imaging time was feasible without pronounced image degradation and with minimal impact on the image signal-to-noise ratio and 19F quantification accuracy. In 19F phantom studies, we show that apparent feature topology is maintained with compressed sensing reconstruction, and false positive signals do not appear in areas devoid of fluorine. We apply the three-dimensional compressed sensing 19F MRI methods to quantify the macrophage burden in a localized wounding-inflammation mouse model in vivo; at 8-fold image acceleration, the 19F signal distribution was accurately reproduced, with no loss in signal-to-noise ratio. Our results demonstrate that three-dimensional compressed sensing methods have potential for advancing in vivo 19F cell tracking for a wide range of preclinical and translational applications.
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Affiliation(s)
- Jia Zhong
- Department of Biological Sciences & the Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
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Ibrahim ESH. Imaging sequences in cardiovascular magnetic resonance: current role, evolving applications, and technical challenges. Int J Cardiovasc Imaging 2012; 28:2027-47. [PMID: 22447266 DOI: 10.1007/s10554-012-0038-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 03/10/2012] [Indexed: 12/25/2022]
Abstract
Cardiovascular magnetic resonance (CMR) has been established as a powerful and comprehensive imaging modality for studying the cardiovascular (CV) system. Shortly after invention of magnetic resonance imaging, CMR applications and developments started to emerge, and they continue to evolve up to the present day. CMR has the advantages of high spatial resolution, enhanced tissue contrast, superior safety profile, and the plethora of physiological parameters that can be obtained. In the near future, CMR is expected to be the gold standard modality for comprehensive CV imaging. Specifically, CMR imaging sequences are increasingly growing in parallel with advancements in scanner hardware. Not only do CMR imaging sequences provide detailed anatomical information, but they also provide functional, perfusion, viability, hemodynamic, and metabolic information about the CV system. In this article, an up-to-date review of different CMR imaging sequences is presented. Each sequence is described along with typical imaging parameters, necessary image processing steps, derived CV parameters, and potential applications. The article then addresses advanced CMR imaging techniques and emerging applications. Finally, the challenges facing CMR imaging are discussed along with its expected future role.
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Affiliation(s)
- El-Sayed H Ibrahim
- Department of Radiology, University of Florida, 655 W 8th St, Jacksonville, FL 32209, USA.
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Lin W, Huang F, Simonotto E, Duensing GR, Reykowski A. Off-resonance artifacts correction with convolution in k-space (ORACLE). Magn Reson Med 2011; 67:1547-55. [DOI: 10.1002/mrm.23135] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 06/24/2011] [Accepted: 07/12/2011] [Indexed: 11/11/2022]
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Lin W, Börnert P, Huang F, Duensing GR, Reykowski A. Generalized GRAPPA operators for wider spiral bands: Rapid self-calibrated parallel reconstruction for variable density spiral MRI. Magn Reson Med 2011; 66:1067-78. [DOI: 10.1002/mrm.22900] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 12/13/2010] [Accepted: 02/08/2011] [Indexed: 11/06/2022]
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Oshinski JN, Delfino JG, Sharma P, Gharib AM, Pettigrew RI. Cardiovascular magnetic resonance at 3.0 T: current state of the art. J Cardiovasc Magn Reson 2010; 12:55. [PMID: 20929538 PMCID: PMC2964699 DOI: 10.1186/1532-429x-12-55] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 10/07/2010] [Indexed: 12/12/2022] Open
Abstract
There are advantages to conducting cardiovascular magnetic resonance (CMR) studies at a field strength of 3.0 Telsa, including the increase in bulk magnetization, the increase in frequency separation of off-resonance spins, and the increase in T1 of many tissues. However, there are significant challenges to routinely performing CMR at 3.0 T, including the reduction in main magnetic field homogeneity, the increase in RF power deposition, and the increase in susceptibility-based artifacts.In this review, we outline the underlying physical effects that occur when imaging at higher fields, examine the practical results these effects have on the CMR applications, and examine methods used to compensate for these effects. Specifically, we will review cine imaging, MR coronary angiography, myocardial perfusion imaging, late gadolinium enhancement, and vascular wall imaging.
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Affiliation(s)
- John N Oshinski
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, Room AG34, Atlanta, GA 30322, USA
- Department of Biomedical Engineering, Emory University and the Georgia Institute of Technology, 101 Woodruff Circle Woodruff Memorial Building, Suite 2001, Atlanta, Georgia 30322, USA
| | - Jana G Delfino
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, Room AG34, Atlanta, GA 30322, USA
| | - Puneet Sharma
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, Room AG34, Atlanta, GA 30322, USA
| | - Ahmed M Gharib
- Laboratory of Integrative Cardiovascular Imaging, Department of Radiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bldg. 10, Rm. 3-5340, MSC 1263, 10 Center Dr., Bethesda, MD 20892, USA
| | - Roderic I Pettigrew
- Laboratory of Integrative Cardiovascular Imaging, Department of Radiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bldg. 10, Rm. 3-5340, MSC 1263, 10 Center Dr., Bethesda, MD 20892, USA
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Cukur T, Santos JM, Pauly JM, Nishimura DG. Variable-density parallel imaging with partially localized coil sensitivities. IEEE TRANSACTIONS ON MEDICAL IMAGING 2010; 29:1173-1181. [PMID: 20236876 PMCID: PMC3155390 DOI: 10.1109/tmi.2010.2042805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Partially parallel imaging with localized sensitivities is a fast parallel image reconstruction method for both Cartesian and non-Cartesian trajectories, but suffers from aliasing artifacts when there are deviations from the assumption of perfect localization. Such reconstructions would normally crop the individual coil images to remove the artifacts prior to combination. However, the sampling densities in variable-density k-space trajectories support different field-of-views for separate regions in k -space. In fact, the higher sampling density of low frequencies can be used to reconstruct a bigger field-of-view without introducing aliasing artifacts and the resulting image signal-to-noise ratio (SNR) can be improved. A novel, fast variable-density parallel imaging method is presented, which reconstructs different field-of-views from separate frequencies according to the local sampling density in k-space. Aliasing-suppressed images can be produced with high SNR-efficiency without the need for accurate estimation of coil sensitivities and complex or iterative computations.
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Affiliation(s)
- Tolga Cukur
- Information Systems Laboratory, Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
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Delattre BMA, Heidemann RM, Crowe LA, Vallée JP, Hyacinthe JN. Spiral demystified. Magn Reson Imaging 2010; 28:862-81. [PMID: 20409660 DOI: 10.1016/j.mri.2010.03.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/24/2010] [Accepted: 03/05/2010] [Indexed: 10/19/2022]
Abstract
Spiral acquisition schemes offer unique advantages such as flow compensation, efficient k-space sampling and robustness against motion that make this option a viable choice among other non-Cartesian sampling schemes. For this reason, the main applications of spiral imaging lie in dynamic magnetic resonance imaging such as cardiac imaging and functional brain imaging. However, these advantages are counterbalanced by practical difficulties that render spiral imaging quite challenging. Firstly, the design of gradient waveforms and its hardware requires specific attention. Secondly, the reconstruction of such data is no longer straightforward because k-space samples are no longer aligned on a Cartesian grid. Thirdly, to take advantage of parallel imaging techniques, the common generalized autocalibrating partially parallel acquisitions (GRAPPA) or sensitivity encoding (SENSE) algorithms need to be extended. Finally, and most notably, spiral images are prone to particular artifacts such as blurring due to gradient deviations and off-resonance effects caused by B(0) inhomogeneity and concomitant gradient fields. In this article, various difficulties that spiral imaging brings along, and the solutions, which have been developed and proposed in literature, will be reviewed in detail.
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Affiliation(s)
- Bénédicte M A Delattre
- Radiology Clinic, Geneva University Hospital and Faculty of Medicine, University of Geneva, 1211 Geneva 14, Switzerland.
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31
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Holbrook AB, Santos JM, Kaye E, Rieke V, Pauly KB. Real-time MR thermometry for monitoring HIFU ablations of the liver. Magn Reson Med 2010; 63:365-73. [PMID: 19950255 DOI: 10.1002/mrm.22206] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A high-resolution and high-speed pulse sequence is presented for monitoring high-intensity focused ultrasound ablations in the liver in the presence of motion. The sequence utilizes polynomial-order phase saturation bands to perform outer volume suppression, followed by spatial-spectral excitation and three readout segmented echo-planar imaging interleaves. Images are processed with referenceless thermometry to create temperature-rise images every frame. The sequence and reconstruction were implemented in RTHawk and used to image stationary and moving sonications in a polyacrylamide gel phantom (62.4 acoustic W, 50 sec, 550 kHz). Temperature-rise images were compared between moving and stationary experiments. Heating spots and corresponding temperature-rise plots matched very well. The stationary sonication had a temperature standard deviation of 0.15 degrees C compared to values of 0.28 degrees C and 0.43 degrees C measured for two manually moved sonications at different velocities. Moving the phantom (while not heating) with respect to the transducer did not cause false temperature rises, despite susceptibility changes. The system was tested on nonheated livers of five normal volunteers. The mean temperature rise was -0.05 degrees C, with a standard deviation of 1.48 degrees C. This standard deviation is acceptable for monitoring high-intensity focused ultrasound ablations, suggesting real-time imaging of moving high-intensity focused ultrasound sonications can be clinically possible.
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Affiliation(s)
- Andrew B Holbrook
- Department of Bioengineering, Stanford University, Stanford, California, USA.
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Seeger M, Nickisch H, Pohmann R, Schölkopf B. Optimization of k-space trajectories for compressed sensing by Bayesian experimental design. Magn Reson Med 2010; 63:116-26. [PMID: 19859957 DOI: 10.1002/mrm.22180] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The optimization of k-space sampling for nonlinear sparse MRI reconstruction is phrased as a Bayesian experimental design problem. Bayesian inference is approximated by a novel relaxation to standard signal processing primitives, resulting in an efficient optimization algorithm for Cartesian and spiral trajectories. On clinical resolution brain image data from a Siemens 3T scanner, automatically optimized trajectories lead to significantly improved images, compared to standard low-pass, equispaced, or variable density randomized designs. Insights into the nonlinear design optimization problem for MRI are given.
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Affiliation(s)
- Matthias Seeger
- Department of Computer Science, Saarland University, Saarbrücken, Germany.
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White N, Roddey C, Shankaranarayanan A, Han E, Rettmann D, Santos J, Kuperman J, Dale A. PROMO: Real-time prospective motion correction in MRI using image-based tracking. Magn Reson Med 2010; 63:91-105. [PMID: 20027635 DOI: 10.1002/mrm.22176] [Citation(s) in RCA: 257] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Artifacts caused by patient motion during scanning remain a serious problem in most MRI applications. The prospective motion correction technique attempts to address this problem at its source by keeping the measurement coordinate system fixed with respect to the patient throughout the entire scan process. In this study, a new image-based approach for prospective motion correction is described, which utilizes three orthogonal two-dimensional spiral navigator acquisitions, along with a flexible image-based tracking method based on the extended Kalman filter algorithm for online motion measurement. The spiral navigator/extended Kalman filter framework offers the advantages of image-domain tracking within patient-specific regions-of-interest and reduced sensitivity to off-resonance-induced corruption of rigid-body motion estimates. The performance of the method was tested using offline computer simulations and online in vivo head motion experiments. In vivo validation results covering a broad range of staged head motions indicate a steady-state error of less than 10% of the motion magnitude, even for large compound motions that included rotations over 15 deg. A preliminary in vivo application in three-dimensional inversion recovery spoiled gradient echo (IR-SPGR) and three-dimensional fast spin echo (FSE) sequences demonstrates the effectiveness of the spiral navigator/extended Kalman filter framework for correcting three-dimensional rigid-body head motion artifacts prospectively in high-resolution three-dimensional MRI scans.
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Affiliation(s)
- Nathan White
- Department of Cognitive Science, University of California, San Diego, La Jolla, California 92037, USA
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34
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Sümbül U, Santos JM, Pauly JM. Improved time series reconstruction for dynamic magnetic resonance imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2009; 28:1093-104. [PMID: 19150785 PMCID: PMC2766564 DOI: 10.1109/tmi.2008.2012030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Time series of in vivo magnetic resonance images exhibit high levels of temporal correlation. Higher temporal resolution reconstructions are obtained by acquiring data at a fraction of the Nyquist rate and resolving the resulting aliasing using the correlation information. The dynamic imaging experiment is modeled as a linear dynamical system. A Kalman filter based unaliasing reconstruction is described for accelerated dynamic magnetic resonance imaging (MRI). The algorithm handles arbitrary readout trajectories naturally. The reconstruction is causal and very fast, making it applicable to real-time imaging. In vivo results are presented for cardiac MRI of healthy volunteers.
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Affiliation(s)
- Uygar Sümbül
- Information Systems Laboratory, Department ofElectrical Engineering, Stanford University, Stanford, CA 94305 USA.
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Stoeck CT, Han Y, Peters DC, Hu P, Yeon SB, Kissinger KV, Goddu B, Goepfert L, Manning WJ, Kozerke S, Nezafat R. Whole heart magnetization-prepared steady-state free precession coronary vein MRI. J Magn Reson Imaging 2009; 29:1293-9. [DOI: 10.1002/jmri.21788] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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36
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Terashima M, Nguyen PK, Rubin GD, Iribarren C, Courtney BK, Go AS, Fortmann SP, McConnell MV. Impaired Coronary Vasodilation by Magnetic Resonance Angiography Is Associated With Advanced Coronary Artery Calcification. JACC Cardiovasc Imaging 2008; 1:167-73. [DOI: 10.1016/j.jcmg.2007.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 12/05/2007] [Accepted: 12/08/2007] [Indexed: 11/16/2022]
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Lustig M, Donoho D, Pauly JM. Sparse MRI: The application of compressed sensing for rapid MR imaging. Magn Reson Med 2008; 58:1182-95. [PMID: 17969013 DOI: 10.1002/mrm.21391] [Citation(s) in RCA: 2995] [Impact Index Per Article: 187.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The sparsity which is implicit in MR images is exploited to significantly undersample k-space. Some MR images such as angiograms are already sparse in the pixel representation; other, more complicated images have a sparse representation in some transform domain-for example, in terms of spatial finite-differences or their wavelet coefficients. According to the recently developed mathematical theory of compressed-sensing, images with a sparse representation can be recovered from randomly undersampled k-space data, provided an appropriate nonlinear recovery scheme is used. Intuitively, artifacts due to random undersampling add as noise-like interference. In the sparse transform domain the significant coefficients stand out above the interference. A nonlinear thresholding scheme can recover the sparse coefficients, effectively recovering the image itself. In this article, practical incoherent undersampling schemes are developed and analyzed by means of their aliasing interference. Incoherence is introduced by pseudo-random variable-density undersampling of phase-encodes. The reconstruction is performed by minimizing the l(1) norm of a transformed image, subject to data fidelity constraints. Examples demonstrate improved spatial resolution and accelerated acquisition for multislice fast spin-echo brain imaging and 3D contrast enhanced angiography.
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Affiliation(s)
- Michael Lustig
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305-9510, USA.
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Niendorf T, Sodickson DK. Highly accelerated cardiovascular MR imaging using many channel technology: concepts and clinical applications. Eur Radiol 2008; 18:87-102. [PMID: 17562047 PMCID: PMC2838248 DOI: 10.1007/s00330-007-0692-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2006] [Revised: 04/26/2007] [Accepted: 05/10/2007] [Indexed: 01/23/2023]
Abstract
Cardiovascular magnetic resonance imaging (CVMRI) is of proven clinical value in the non-invasive imaging of cardiovascular diseases. CVMRI requires rapid image acquisition, but acquisition speed is fundamentally limited in conventional MRI. Parallel imaging provides a means for increasing acquisition speed and efficiency. However, signal-to-noise (SNR) limitations and the limited number of receiver channels available on most MR systems have in the past imposed practical constraints, which dictated the use of moderate accelerations in CVMRI. High levels of acceleration, which were unattainable previously, have become possible with many-receiver MR systems and many-element, cardiac-optimized RF-coil arrays. The resulting imaging speed improvements can be exploited in a number of ways, ranging from enhancement of spatial and temporal resolution to efficient whole heart coverage to streamlining of CVMRI work flow. In this review, examples of these strategies are provided, following an outline of the fundamentals of the highly accelerated imaging approaches employed in CVMRI. Topics discussed include basic principles of parallel imaging; key requirements for MR systems and RF-coil design; practical considerations of SNR management, supported by multi-dimensional accelerations, 3D noise averaging and high field imaging; highly accelerated clinical state-of-the art cardiovascular imaging applications spanning the range from SNR-rich to SNR-limited; and current trends and future directions.
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Affiliation(s)
- Thoralf Niendorf
- Department of Diagnostic Radiology, RWTH Aachen, University Hospital, Pauwelsstrasse 30, 52057 Aachen, Germany, Tel.: +49-241-8080295, Fax: +49-241-803380295
| | - Daniel K. Sodickson
- Department of Radiology, Center for Biomedical Imaging, New York University, School of Medicine, 650 First Avenue, Suite 600-A, New York, NY, 10016, USA, Tel.: 212-263-4844, Fax: 212-263-4845
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Three-dimensional breathhold magnetization-prepared TrueFISP: a pilot study for magnetic resonance imaging of the coronary artery disease. Invest Radiol 2007; 42:665-70. [PMID: 17984762 DOI: 10.1097/rli.0b013e3180661a77] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE X-ray angiography is currently the standard test for the assessment of coronary artery disease. A substantial minority of patients referred for coronary angiography have no significant coronary artery disease. The purpose of this work was the evaluation of the accuracy of a three-dimensional (3D) breathhold coronary magnetic resonance angiography (MRA) technique in detecting hemodynamically significant coronary artery stenoses in a patient population with x-ray angiographic correlation. MATERIALS AND METHODS Sequential subjects (n = 33, M/F = 22/11, average age = 57) who were referred for conventional coronary angiography were enrolled in the study. The study protocol was approved by our institutional review board. Each subject gave written informed consent. Volume-targeted 3D breathhold coronary artery scans with ECG-triggered, segmented True Fast Imaging with Steady-state Precession (TrueFISP) were acquired for the left main (LM), left anterior descending (LAD), and right coronary arteries (RCAs). Coronary MRA was evaluated with conventional angiography as the gold standard. RESULTS The overall sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for diagnosing any hemodynamically significant coronary artery disease (> or =50% diameter reduction) with coronary MRA was 87%, 57%, 72%, 68%, and 80%, respectively. The sensitivity of the technique in the LM, LAD, and RCA was 100%, 83%, and 100%, respectively. The NPV of the technique in the LM, LAD, and RCA was 100%, 82%, and 100%, respectively. CONCLUSIONS Three-dimensional breathhold True Fast Imaging with Steady-state Precession is a promising technique for coronary artery imaging. It has a relatively high sensitivity and NPV. Results of this study warrant further technical improvements and clinical evaluation of the technique.
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deCharms RC. Reading and controlling human brain activation using real-time functional magnetic resonance imaging. Trends Cogn Sci 2007; 11:473-81. [PMID: 17988931 DOI: 10.1016/j.tics.2007.08.014] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 08/20/2007] [Accepted: 08/20/2007] [Indexed: 11/25/2022]
Abstract
Understanding how to control how the brain's functioning mediates mental experience and the brain's processing to alter cognition or disease are central projects of cognitive and neural science. The advent of real-time functional magnetic resonance imaging (rtfMRI) now makes it possible to observe the biology of one's own brain while thinking, feeling and acting. Recent evidence suggests that people can learn to control brain activation in localized regions, with corresponding changes in their mental operations, by observing information from their brain while inside an MRI scanner. For example, subjects can learn to deliberately control activation in brain regions involved in pain processing with corresponding changes in experienced pain. This may provide a novel, non-invasive means of observing and controlling brain function, potentially altering cognitive processes or disease.
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Manning WJ, Nezafat R, Appelbaum E, Danias PG, Hauser TH, Yeon SB. Coronary Magnetic Resonance Imaging. Magn Reson Imaging Clin N Am 2007; 15:609-37, vii. [DOI: 10.1016/j.mric.2007.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
This article highlights the technical challenges and general imaging strategies for coronary MRI. This is followed by a review of the clinical results for the assessment of anomalous CAD, coronary artery aneurysms, native vessel integrity, and coronary artery bypass graft disease using the more commonly applied MRI methods. It concludes with a brief discussion of the advantages/disadvantages and clinical results comparing coronary MRI with multidetector CT (MDCT) coronary angiography.
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Affiliation(s)
- Warren J Manning
- Departments of Medicine and Radiology, Cardiovascular Division, Harvard-Thorndike Laboratory, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA.
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Stehning C, Boernert P, Nehrke K. Advances in Coronary MRA from Vessel Wall to Whole Heart Imaging. Magn Reson Med Sci 2007; 6:157-70. [PMID: 18037796 DOI: 10.2463/mrms.6.157] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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44
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El-Sharkawy AM, Schär M, Bottomley PA, Atalar E. Monitoring and correcting spatio-temporal variations of the MR scanner's static magnetic field. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2006; 19:223-36. [PMID: 17043837 PMCID: PMC1945237 DOI: 10.1007/s10334-006-0050-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 08/16/2006] [Accepted: 08/24/2006] [Indexed: 11/28/2022]
Abstract
The homogeneity and stability of the static magnetic field are of paramount importance to the accuracy of MR procedures that are sensitive to phase errors and magnetic field inhomogeneity. It is shown that intense gradient utilization in clinical horizontal-bore superconducting MR scanners of three different vendors results in main magnetic fields that vary on a long time scale both spatially and temporally by amounts of order 0.8-2.5 ppm. The observed spatial changes have linear and quadratic variations that are strongest along the z direction. It is shown that the effect of such variations is of sufficient magnitude to completely obfuscate thermal phase shifts measured by proton-resonance frequency-shift MR thermometry and certainly affect accuracy. In addition, field variations cause signal loss and line-broadening in MR spectroscopy, as exemplified by a fourfold line-broadening of metabolites over the course of a 45 min human brain study. The field variations are consistent with resistive heating of the magnet structures. It is concluded that correction strategies are required to compensate for these spatial and temporal field drifts for phase-sensitive MR protocols. It is demonstrated that serial field mapping and phased difference imaging correction protocols can substantially compensate for the drift effects observed in the MR thermometry and spectroscopy experiments.
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Affiliation(s)
- AbdEl Monem El-Sharkawy
- The Departments of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Michael Schär
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA, Philips Medical Systems, Cleveland, OH, USA
| | - Paul A. Bottomley
- The Departments of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Ergin Atalar
- The Departments of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA, The Department of Electrical and Electronics Engineering, Bilkent University, Bilkent Ankara 06533, Turkey E-mail:
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