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Knoll F, Raya JG, Halloran RO, Baete S, Sigmund E, Bammer R, Block T, Otazo R, Sodickson DK. A model-based reconstruction for undersampled radial spin-echo DTI with variational penalties on the diffusion tensor. NMR Biomed 2015; 28:353-66. [PMID: 25594167 PMCID: PMC4339452 DOI: 10.1002/nbm.3258] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 12/08/2014] [Accepted: 12/17/2014] [Indexed: 05/04/2023]
Abstract
Radial spin-echo diffusion imaging allows motion-robust imaging of tissues with very low T2 values like articular cartilage with high spatial resolution and signal-to-noise ratio (SNR). However, in vivo measurements are challenging, due to the significantly slower data acquisition speed of spin-echo sequences and the less efficient k-space coverage of radial sampling, which raises the demand for accelerated protocols by means of undersampling. This work introduces a new reconstruction approach for undersampled diffusion-tensor imaging (DTI). A model-based reconstruction implicitly exploits redundancies in the diffusion-weighted images by reducing the number of unknowns in the optimization problem and compressed sensing is performed directly in the target quantitative domain by imposing a total variation (TV) constraint on the elements of the diffusion tensor. Experiments were performed for an anisotropic phantom and the knee and brain of healthy volunteers (three and two volunteers, respectively). Evaluation of the new approach was conducted by comparing the results with reconstructions performed with gridding, combined parallel imaging and compressed sensing and a recently proposed model-based approach. The experiments demonstrated improvements in terms of reduction of noise and streaking artifacts in the quantitative parameter maps, as well as a reduction of angular dispersion of the primary eigenvector when using the proposed method, without introducing systematic errors into the maps. This may enable an essential reduction of the acquisition time in radial spin-echo diffusion-tensor imaging without degrading parameter quantification and/or SNR.
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Affiliation(s)
- Florian Knoll
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
- Correspondence to: Florian Knoll, PhD, New York University School of Medicine, Center for Biomedical Imaging, 660 First Avenue, 4th Floor, New York, NY 10016, Phone: 212-263-0335,
| | - José G Raya
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
| | - Rafael O Halloran
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Steven Baete
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
| | - Eric Sigmund
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
| | - Roland Bammer
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Tobias Block
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
| | - Ricardo Otazo
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
| | - Daniel K Sodickson
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
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Rosenkrantz AB, Geppert C, Grimm R, Block TK, Glielmi C, Feng L, Otazo R, Ream JM, Romolo MM, Taneja SS, Sodickson DK, Chandarana H. Dynamic contrast-enhanced MRI of the prostate with high spatiotemporal resolution using compressed sensing, parallel imaging, and continuous golden-angle radial sampling: preliminary experience. J Magn Reson Imaging 2014; 41:1365-73. [PMID: 24833417 DOI: 10.1002/jmri.24661] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 04/24/2014] [Accepted: 04/28/2014] [Indexed: 01/06/2023] Open
Abstract
PURPOSE To demonstrate dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) of the prostate with both high spatial and temporal resolution via a combination of golden-angle radial k-space sampling, compressed sensing, and parallel-imaging reconstruction (GRASP), and to compare image quality and lesion depiction between GRASP and conventional DCE in prostate cancer patients. MATERIALS AND METHODS Twenty prostate cancer patients underwent two 3T prostate MRI examinations on separate dates, one using standard DCE (spatial resolution 3.0 × 1.9 × 1.9 mm, temporal resolution 5.5 sec) and the other using GRASP (spatial resolution 3.0 × 1.1 × 1.1 mm, temporal resolution 2.3 sec). Two radiologists assessed measures of image quality and dominant lesion size. The experienced reader recorded differences in contrast arrival times between the dominant lesion and benign prostate. RESULTS Compared with standard DCE, GRASP demonstrated significantly better clarity of the capsule, peripheral/transition zone boundary, urethra, and periprostatic vessels; image sharpness; and lesion conspicuity for both readers (P < 0.001-0.020). GRASP showed improved interreader correlation for lesion size (GRASP: r = 0.691-0.824, standard: r = 0.495-0.542). In 8/20 cases, only GRASP showed earlier contrast arrival in tumor than benign; in no case did only standard DCE show earlier contrast arrival in tumor. CONCLUSION High spatiotemporal resolution prostate DCE is possible with GRASP, which has the potential to improve image quality and lesion depiction as compared with standard DCE.
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Feng L, Axel L, Xu J, Sodickson DK, Otazo R. Synchronized cardiac and respiratory sparsity for rapid free-breathing cardiac cine MRI. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044195 DOI: 10.1186/1532-429x-16-s1-w26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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Feng L, Grimm R, Block KT, Chandarana H, Kim S, Xu J, Axel L, Sodickson DK, Otazo R. Golden-angle radial sparse parallel MRI: combination of compressed sensing, parallel imaging, and golden-angle radial sampling for fast and flexible dynamic volumetric MRI. Magn Reson Med 2013; 72:707-17. [PMID: 24142845 DOI: 10.1002/mrm.24980] [Citation(s) in RCA: 430] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 09/12/2013] [Accepted: 09/12/2013] [Indexed: 12/25/2022]
Abstract
PURPOSE To develop a fast and flexible free-breathing dynamic volumetric MRI technique, iterative Golden-angle RAdial Sparse Parallel MRI (iGRASP), that combines compressed sensing, parallel imaging, and golden-angle radial sampling. METHODS Radial k-space data are acquired continuously using the golden-angle scheme and sorted into time series by grouping an arbitrary number of consecutive spokes into temporal frames. An iterative reconstruction procedure is then performed on the undersampled time series where joint multicoil sparsity is enforced by applying a total-variation constraint along the temporal dimension. Required coil-sensitivity profiles are obtained from the time-averaged data. RESULTS iGRASP achieved higher acceleration capability than either parallel imaging or coil-by-coil compressed sensing alone. It enabled dynamic volumetric imaging with high spatial and temporal resolution for various clinical applications, including free-breathing dynamic contrast-enhanced imaging in the abdomen of both adult and pediatric patients, and in the breast and neck of adult patients. CONCLUSION The high performance and flexibility provided by iGRASP can improve clinical studies that require robustness to motion and simultaneous high spatial and temporal resolution. Magn Reson Med 72:707-717, 2014. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Li Feng
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine New York, New York, USA; Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine New York, New York, 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Parasoglou P, Feng L, Xia D, Otazo R, Regatte RR. Rapid 3D-imaging of phosphocreatine recovery kinetics in the human lower leg muscles with compressed sensing. Magn Reson Med 2012; 68:1738-46. [PMID: 23023624 DOI: 10.1002/mrm.24484] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/09/2012] [Accepted: 08/13/2012] [Indexed: 12/30/2022]
Abstract
The rate of phosphocreatine (PCr) resynthesis following physical exercise is an accepted index of mitochondrial oxidative metabolism and has been studied extensively with unlocalized (31)P-MRS methods and small surface coils. Imaging experiments using volume coils that measure several muscles simultaneously can provide new insights into the variability of muscle function in healthy and diseased states. However, they are limited by long acquisition times relative to the dynamics of PCr recovery. This work focuses on the implementation of a compressed sensing technique to accelerate imaging of PCr resynthesis following physical exercise, using a modified three-dimensional turbo-spin-echo sequence and principal component analysis as sparsifying transform. The compressed sensing technique was initially validated using 2-fold retrospective undersampling of fully sampled data from four volunteers acquired on a 7T MRI system (voxel size: 1.6 mL, temporal resolution: 24 s), which led to an accurate estimation of the mono-exponential PCr resynthesis rate constant (mean error <6.4%). Acquisitions with prospective 2-fold acceleration (temporal resolution: 12 s) demonstrated that three-dimensional mapping of PCr resynthesis is possible at a temporal resolution that is sufficiently high for characterizing the recovery curve of several muscles in a single measurement.
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Affiliation(s)
- Prodromos Parasoglou
- Department of Radiology, Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), New York University Langone Medical Center, New York, New York 10016, USA.
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Feng L, Srichai MB, Lim RP, Harrison A, King W, Adluru G, Dibella EVR, Sodickson DK, Otazo R, Kim D. Highly accelerated real-time cardiac cine MRI using k-t SPARSE-SENSE. Magn Reson Med 2012; 70:64-74. [PMID: 22887290 DOI: 10.1002/mrm.24440] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 06/20/2012] [Accepted: 07/03/2012] [Indexed: 01/19/2023]
Abstract
For patients with impaired breath-hold capacity and/or arrhythmias, real-time cine MRI may be more clinically useful than breath-hold cine MRI. However, commercially available real-time cine MRI methods using parallel imaging typically yield relatively poor spatio-temporal resolution due to their low image acquisition speed. We sought to achieve relatively high spatial resolution (∼2.5 × 2.5 mm(2)) and temporal resolution (∼40 ms), to produce high-quality real-time cine MR images that could be applied clinically for wall motion assessment and measurement of left ventricular function. In this work, we present an eightfold accelerated real-time cardiac cine MRI pulse sequence using a combination of compressed sensing and parallel imaging (k-t SPARSE-SENSE). Compared with reference, breath-hold cine MRI, our eightfold accelerated real-time cine MRI produced significantly worse qualitative grades (1-5 scale), but its image quality and temporal fidelity scores were above 3.0 (adequate) and artifacts and noise scores were below 3.0 (moderate), suggesting that acceptable diagnostic image quality can be achieved. Additionally, both eightfold accelerated real-time cine and breath-hold cine MRI yielded comparable left ventricular function measurements, with coefficient of variation <10% for left ventricular volumes. Our proposed eightfold accelerated real-time cine MRI with k-t SPARSE-SENSE is a promising modality for rapid imaging of myocardial function.
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Affiliation(s)
- Li Feng
- Department of Radiology, The Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York 10016, USA.
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Madelin G, Chang G, Otazo R, Jerschow A, Regatte RR. Compressed sensing sodium MRI of cartilage at 7T: preliminary study. J Magn Reson 2012; 214:360-5. [PMID: 22204825 PMCID: PMC3278671 DOI: 10.1016/j.jmr.2011.12.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 12/01/2011] [Accepted: 12/03/2011] [Indexed: 05/11/2023]
Abstract
Sodium MRI has been shown to be highly specific for glycosaminoglycan (GAG) content in articular cartilage, the loss of which is an early sign of osteoarthritis (OA). Quantitative sodium MRI techniques are therefore under development in order to detect and assess early biochemical degradation of cartilage, but due to low sodium NMR sensitivity and its low concentration, sodium images need long acquisition times (15-25 min) even at high magnetic fields and are typically of low resolution. In this preliminary study, we show that compressed sensing can be applied to reduce the acquisition time by a factor of 2 at 7 T without losing sodium quantification accuracy. Alternatively, the nonlinear reconstruction technique can be used to denoise fully-sampled images. We expect to even further reduce this acquisition time by using parallel imaging techniques combined with SNR-improved 3D sequences at 3T and 7 T.
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Affiliation(s)
- Guillaume Madelin
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
- Chemistry Department, New York University, New York, NY, USA
| | - Gregory Chang
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
| | - Ricardo Otazo
- Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
| | - Alexej Jerschow
- Chemistry Department, New York University, New York, NY, USA
- Corresponding author: Chemistry Department, New York University, New York, NY 10012.
| | - Ravinder R. Regatte
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
- Corresponding author: Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, New York University Medical Center, 660 First Avenue, 4th Floor, New York, NY 10016, USA.
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Feng L, Otazo R, Srichai MB, Lim RP, Sodickson DK, Kim D. Highly-Accelerated Real-Time Cine MRI using compressed sensing and parallel imaging. J Cardiovasc Magn Reson 2011. [PMCID: PMC3106946 DOI: 10.1186/1532-429x-13-s1-p25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Kim D, Dyvorne HA, Otazo R, Feng L, Sodickson DK, Lee VS. Accelerated phase-contrast cine MRI using k-t SPARSE-SENSE. Magn Reson Med 2011; 67:1054-64. [PMID: 22083998 DOI: 10.1002/mrm.23088] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 06/10/2011] [Accepted: 06/14/2011] [Indexed: 11/09/2022]
Abstract
Phase-contrast (PC) cine MRI is a promising method for assessment of pathologic hemodynamics, including cardiovascular and hepatoportal vascular dynamics, but its low data acquisition efficiency limits the achievable spatial and temporal resolutions within clinically acceptable breath-hold durations. We propose to accelerate PC cine MRI using an approach which combines compressed sensing and parallel imaging (k-t SPARSE-SENSE). We validated the proposed 6-fold accelerated PC cine MRI against 3-fold accelerated PC cine MRI with parallel imaging (generalized autocalibrating partially parallel acquisitions). With the programmable flow pump, we simulated a time varying waveform emulating hepatic blood flow. Normalized root mean square error between two sets of velocity measurements was 2.59%. In multiple blood vessels of 12 control subjects, two sets of mean velocity measurements were in good agreement (mean difference = -0.29 cm/s; lower and upper 95% limits of agreement = -5.26 and 4.67 cm/s, respectively). The mean phase noise, defined as the standard deviation of the phase in a homogeneous stationary region, was significantly lower for k-t SPARSE-SENSE than for generalized autocalibrating partially parallel acquisitions (0.05 ± 0.01 vs. 0.19 ± 0.06 radians, respectively; P < 0.01). The proposed 6-fold accelerated PC cine MRI pulse sequence with k-t SPARSE-SENSE is a promising investigational method for rapid velocity measurement with relatively high spatial (1.7 mm × 1.7 mm) and temporal (∼35 ms) resolutions.
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Affiliation(s)
- Daniel Kim
- Department of Radiology, New York University School of Medicine, New York, NY, USA.
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Storey P, Otazo R, Lim RP, Kim S, Fleysher L, Oesingmann N, Lee VS, Sodickson DK. Exploiting sparsity to accelerate noncontrast MR angiography in the context of parallel imaging. Magn Reson Med 2011; 67:1391-400. [PMID: 22081482 DOI: 10.1002/mrm.23132] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 06/16/2011] [Accepted: 07/11/2011] [Indexed: 11/09/2022]
Abstract
Noncontrast techniques for peripheral MR angiography are receiving renewed interest because of safety concerns about the use of gadolinium in patients with renal insufficiency. One class of techniques involves subtraction of dark-blood images acquired during fast systolic flow from bright-blood images obtained during slow diastolic flow. The goal of this work was to determine whether the inherent sparsity of the difference images could be exploited to achieve greater acceleration without loss of image quality in the context of generalized autocalibrating partially parallel acquisition (GRAPPA). It is shown that noise amplification at high acceleration factors can be reduced by performing subtraction on the raw data, before calculation of the GRAPPA weights, rather than on the final magnitude images. Use of the difference data to calculate the GRAPPA weights decreases the geometry factor (g-factor), because the difference data represent a sparse image set. This demonstrates an inherent property of GRAPPA and does not require the use of compressed sensing. Application of this approach to highly accelerated data from healthy volunteers resulted in similar depiction of large arteries to that obtained with low acceleration and standard reconstruction. However, visualization of very small vessels and arterial branches was compromised.
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Affiliation(s)
- Pippa Storey
- Department of Radiology, New York University School of Medicine, New York, New York 10016, USA.
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Feng L, Otazo R, Jung H, Jensen JH, Ye JC, Sodickson DK, Kim D. Accelerated cardiac T2 mapping using breath-hold multiecho fast spin-echo pulse sequence with k-t FOCUSS. Magn Reson Med 2011; 65:1661-9. [PMID: 21360737 PMCID: PMC3097270 DOI: 10.1002/mrm.22756] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 10/19/2010] [Accepted: 11/18/2010] [Indexed: 11/08/2022]
Abstract
Cardiac T(2) mapping is a promising method for quantitative assessment of myocardial edema and iron overload. We have developed a new multiecho fast spin echo (ME-FSE) pulse sequence for breath-hold T(2) mapping with acceptable spatial resolution. We propose to further accelerate this new ME-FSE pulse sequence using k-t focal underdetermined system solver adapted with a framework that uses both compressed sensing and parallel imaging (e.g., sensitivity encoding) to achieve higher spatial resolution. We imaged 12 control subjects in midventricular short-axis planes and compared the accuracy of T(2) measurements obtained using ME-FSE with generalized autocalibrating partially parallel acquisitions and ME-FSE with k-t focal underdetermined system solver. For image reconstruction, we used a bootstrapping two-step approach, where in the first step fast Fourier transform was used as the sparsifying transform and in the final step principal component analysis was used as the sparsifying transform. When compared with T(2) measurements obtained using generalized autocalibrating partially parallel acquisitions, T(2) measurements obtained using k-t focal underdetermined system solver were in excellent agreement (mean difference = 0.04 msec; upper/lower 95% limits of agreement were 2.26/-2.19 msec, respectively). The proposed accelerated ME-FSE pulse sequence with k-t focal underdetermined system solver is a promising investigational method for rapid T(2) measurement of the heart with relatively high spatial resolution (1.7 × 1.7 mm(2) ).
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Affiliation(s)
- Li Feng
- Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, 10016
| | - Ricardo Otazo
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016
| | - Hong Jung
- Bio-Imaging & Signal Processing Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science & Technology (KAIST), 373-1 Guseong-dong Yuseong-go, Daejon 305-701, Republic of Korea
| | - Jens H. Jensen
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016
| | - Jong C. Ye
- Bio-Imaging & Signal Processing Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science & Technology (KAIST), 373-1 Guseong-dong Yuseong-go, Daejon 305-701, Republic of Korea
| | - Daniel K. Sodickson
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016
| | - Daniel Kim
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016
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Otazo R, Kim D, Axel L, Sodickson DK. Combination of compressed sensing and parallel imaging with respiratory motion correction for highly-accelerated cardiac perfusion MRI. J Cardiovasc Magn Reson 2011. [PMCID: PMC3106797 DOI: 10.1186/1532-429x-13-s1-o98] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Otazo R, Kim D, Axel L, Sodickson DK. Combination of compressed sensing and parallel imaging for highly accelerated first-pass cardiac perfusion MRI. Magn Reson Med 2011; 64:767-76. [PMID: 20535813 DOI: 10.1002/mrm.22463] [Citation(s) in RCA: 356] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
First-pass cardiac perfusion MRI is a natural candidate for compressed sensing acceleration since its representation in the combined temporal Fourier and spatial domain is sparse and the required incoherence can be effectively accomplished by k-t random undersampling. However, the required number of samples in practice (three to five times the number of sparse coefficients) limits the acceleration for compressed sensing alone. Parallel imaging may also be used to accelerate cardiac perfusion MRI, with acceleration factors ultimately limited by noise amplification. In this work, compressed sensing and parallel imaging are combined by merging the k-t SPARSE technique with sensitivity encoding (SENSE) reconstruction to substantially increase the acceleration rate for perfusion imaging. We also present a new theoretical framework for understanding the combination of k-t SPARSE with SENSE based on distributed compressed sensing theory. This framework, which identifies parallel imaging as a distributed multisensor implementation of compressed sensing, enables an estimate of feasible acceleration for the combined approach. We demonstrate feasibility of 8-fold acceleration in vivo with whole-heart coverage and high spatial and temporal resolution using standard coil arrays. The method is relatively insensitive to respiratory motion artifacts and presents similar temporal fidelity and image quality when compared to Generalized autocalibrating partially parallel acquisitions (GRAPPA) with 2-fold acceleration.
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Affiliation(s)
- Ricardo Otazo
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.
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Otazo R, Feng L, Lim R, Duan Q, Wiggins G, Sodickson DK, Kim D. Accelerated 3D carotid MRI using compressed sensing and parallel imaging. J Cardiovasc Magn Reson 2010. [DOI: 10.1186/1532-429x-12-s1-p147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Xu J, Kim D, Otazo R, Ge B, Zuehlsdorff S, Bi X, Stoeckel B, Sodickson D. Single breath-hold whole heart coronary MRA with isotropic spatial resolution using highly-accelerated parallel imaging with a 32-element coil array. J Cardiovasc Magn Reson 2010. [DOI: 10.1186/1532-429x-12-s1-p47] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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68
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Otazo R, Lin FH, Wiggins G, Jordan R, Sodickson D, Posse S. Superresolution parallel magnetic resonance imaging: application to functional and spectroscopic imaging. Neuroimage 2009; 47:220-30. [PMID: 19341804 DOI: 10.1016/j.neuroimage.2009.03.049] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 03/10/2009] [Accepted: 03/19/2009] [Indexed: 11/19/2022] Open
Abstract
Standard parallel magnetic resonance imaging (MRI) techniques suffer from residual aliasing artifacts when the coil sensitivities vary within the image voxel. In this work, a parallel MRI approach known as Superresolution SENSE (SURE-SENSE) is presented in which acceleration is performed by acquiring only the central region of k-space instead of increasing the sampling distance over the complete k-space matrix and reconstruction is explicitly based on intra-voxel coil sensitivity variation. In SURE-SENSE, parallel MRI reconstruction is formulated as a superresolution imaging problem where a collection of low resolution images acquired with multiple receiver coils are combined into a single image with higher spatial resolution using coil sensitivities acquired with high spatial resolution. The effective acceleration of conventional gradient encoding is given by the gain in spatial resolution, which is dictated by the degree of variation of the different coil sensitivity profiles within the low resolution image voxel. Since SURE-SENSE is an ill-posed inverse problem, Tikhonov regularization is employed to control noise amplification. Unlike standard SENSE, for which acceleration is constrained to the phase-encoding dimension/s, SURE-SENSE allows acceleration along all encoding directions--for example, two-dimensional acceleration of a 2D echo-planar acquisition. SURE-SENSE is particularly suitable for low spatial resolution imaging modalities such as spectroscopic imaging and functional imaging with high temporal resolution. Application to echo-planar functional and spectroscopic imaging in human brain is presented using two-dimensional acceleration with a 32-channel receiver coil.
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Affiliation(s)
- Ricardo Otazo
- Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, NM, USA.
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69
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Posse S, Otazo R, Tsai SY, Yoshimoto AE, Lin FH. Single-shot magnetic resonance spectroscopic imaging with partial parallel imaging. Magn Reson Med 2009; 61:541-7. [PMID: 19097245 PMCID: PMC2827332 DOI: 10.1002/mrm.21855] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 09/18/2008] [Indexed: 11/11/2022]
Abstract
A magnetic resonance spectroscopic imaging (MRSI) pulse sequence based on proton-echo-planar-spectroscopic-imaging (PEPSI) is introduced that measures two-dimensional metabolite maps in a single excitation. Echo-planar spatial-spectral encoding was combined with interleaved phase encoding and parallel imaging using SENSE to reconstruct absorption mode spectra. The symmetrical k-space trajectory compensates phase errors due to convolution of spatial and spectral encoding. Single-shot MRSI at short TE was evaluated in phantoms and in vivo on a 3-T whole-body scanner equipped with a 12-channel array coil. Four-step interleaved phase encoding and fourfold SENSE acceleration were used to encode a 16 x 16 spatial matrix with a 390-Hz spectral width. Comparison with conventional PEPSI and PEPSI with fourfold SENSE acceleration demonstrated comparable sensitivity per unit time when taking into account g-factor-related noise increases and differences in sampling efficiency. LCModel fitting enabled quantification of inositol, choline, creatine, and N-acetyl-aspartate (NAA) in vivo with concentration values in the ranges measured with conventional PEPSI and SENSE-accelerated PEPSI. Cramer-Rao lower bounds were comparable to those obtained with conventional SENSE-accelerated PEPSI at the same voxel size and measurement time. This single-shot MRSI method is therefore suitable for applications that require high temporal resolution to monitor temporal dynamics or to reduce sensitivity to tissue movement.
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Affiliation(s)
- Stefan Posse
- Department of Neurology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA.
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Otazo R, Tsai SY, Lin FH, Posse S. Accelerated short-TE 3D proton echo-planar spectroscopic imaging using 2D-SENSE with a 32-channel array coil. Magn Reson Med 2008; 58:1107-16. [PMID: 17968995 DOI: 10.1002/mrm.21426] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
MR spectroscopic imaging (MRSI) with whole brain coverage in clinically feasible acquisition times still remains a major challenge. A combination of MRSI with parallel imaging has shown promise to reduce the long encoding times and 2D acceleration with a large array coil is expected to provide high acceleration capability. In this work a very high-speed method for 3D-MRSI based on the combination of proton echo planar spectroscopic imaging (PEPSI) with regularized 2D-SENSE reconstruction is developed. Regularization was performed by constraining the singular value decomposition of the encoding matrix to reduce the effect of low-value and overlapped coil sensitivities. The effects of spectral heterogeneity and discontinuities in coil sensitivity across the spectroscopic voxels were minimized by unaliasing the point spread function. As a result the contamination from extracranial lipids was reduced 1.6-fold on average compared to standard SENSE. We show that the acquisition of short-TE (15 ms) 3D-PEPSI at 3 T with a 32 x 32 x 8 spatial matrix using a 32-channel array coil can be accelerated 8-fold (R = 4 x 2) along y-z to achieve a minimum acquisition time of 1 min. Maps of the concentrations of N-acetyl-aspartate, creatine, choline, and glutamate were obtained with moderate reduction in spatial-spectral quality. The short acquisition time makes the method suitable for volumetric metabolite mapping in clinical studies.
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Affiliation(s)
- Ricardo Otazo
- Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131, USA.
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Tsai SY, Otazo R, Posse S, Lin YR, Chung HW, Wald LL, Wiggins GC, Lin FH. Accelerated proton echo planar spectroscopic imaging (PEPSI) using GRAPPA with a 32-channel phased-array coil. Magn Reson Med 2008; 59:989-98. [PMID: 18429025 DOI: 10.1002/mrm.21545] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Shang-Yueh Tsai
- Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan
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Posse S, Otazo R, Caprihan A, Bustillo J, Chen H, Henry PG, Marjanska M, Gasparovic C, Zuo C, Magnotta V, Mueller B, Mullins P, Renshaw P, Ugurbil K, Lim KO, Alger JR. Proton echo-planar spectroscopic imaging of J-coupled resonances in human brain at 3 and 4 Tesla. Magn Reson Med 2007; 58:236-44. [PMID: 17610279 DOI: 10.1002/mrm.21287] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this multicenter study, 2D spatial mapping of J-coupled resonances at 3T and 4T was performed using short-TE (15 ms) proton echo-planar spectroscopic imaging (PEPSI). Water-suppressed (WS) data were acquired in 8.5 min with 1-cm(3) spatial resolution from a supraventricular axial slice. Optimized outer volume suppression (OVS) enabled mapping in close proximity to peripheral scalp regions. Constrained spectral fitting in reference to a non-WS (NWS) scan was performed with LCModel using correction for relaxation attenuation and partial-volume effects. The concentrations of total choline (tCho), creatine + phosphocreatine (Cr+PCr), glutamate (Glu), glutamate + glutamine (Glu+Gln), myo-inositol (Ins), NAA, NAA+NAAG, and two macromolecular resonances at 0.9 and 2.0 ppm were mapped with mean Cramer-Rao lower bounds (CRLBs) between 6% and 18% and approximately 150-cm(3) sensitive volumes. Aspartate, GABA, glutamine (Gln), glutathione (GSH), phosphoethanolamine (PE), and macromolecules (MMs) at 1.2 ppm were also mapped, although with larger mean CRLBs between 30% and 44%. The CRLBs at 4T were 19% lower on average as compared to 3T, consistent with a higher signal-to-noise ratio (SNR) and increased spectral resolution. Metabolite concentrations were in the ranges reported in previous studies. Glu concentration was significantly higher in gray matter (GM) compared to white matter (WM), as anticipated. The short acquisition time makes this methodology suitable for clinical studies.
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Affiliation(s)
- Stefan Posse
- Department of Psychiatry, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA.
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Lin FH, Tsai SY, Otazo R, Caprihan A, Wald LL, Belliveau JW, Posse S. Sensitivity-encoded (SENSE) proton echo-planar spectroscopic imaging (PEPSI) in the human brain. Magn Reson Med 2007; 57:249-57. [PMID: 17260356 DOI: 10.1002/mrm.21119] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magnetic resonance spectroscopic imaging (MRSI) provides spatially resolved metabolite information that is invaluable for both neuroscience studies and clinical applications. However, lengthy data acquisition times, which are a result of time-consuming phase encoding, represent a major challenge for MRSI. Fast MRSI pulse sequences that use echo-planar readout gradients, such as proton echo-planar spectroscopic imaging (PEPSI), are capable of fast spectral-spatial encoding and thus enable acceleration of image acquisition times. Combining PEPSI with recent advances in parallel MRI utilizing RF coil arrays can further accelerate MRSI data acquisition. Here we investigate the feasibility of ultrafast spectroscopic imaging at high field (3T and 4T) by combining PEPSI with sensitivity-encoded (SENSE) MRI using eight-channel head coil arrays. We show that the acquisition of single-average SENSE-PEPSI data at a short TE (15 ms) can be accelerated to 32 s or less, depending on the field strength, to obtain metabolic images of choline (Cho), creatine (Cre), N-acetyl-aspartate (NAA), and J-coupled metabolites (e.g., glutamate (Glu) and inositol (Ino)) with acceptable spectral quality and localization. The experimentally measured reductions in signal-to-noise ratio (SNR) and Cramer-Rao lower bounds (CRLBs) of metabolite resonances were well explained by both the g-factor and reduced measurement times. Thus, this technology is a promising means of reducing the scan times of 3D acquisitions and time-resolved 2D measurements.
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Affiliation(s)
- Fa-Hsuan Lin
- MGH-HMS-MIT Athinoula A. Martinos Center for Biomedical Imaging, Charlestown 02129, and Department of Radiology, Massachusetts General Hospital, Boston, USA.
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Otazo R, Mueller B, Ugurbil K, Wald L, Posse S. Signal-to-noise ratio and spectral linewidth improvements between 1.5 and 7 Tesla in proton echo-planar spectroscopic imaging. Magn Reson Med 2007; 56:1200-10. [PMID: 17094090 DOI: 10.1002/mrm.21067] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study characterizes gains in sensitivity and spectral resolution of proton echo-planar spectroscopic imaging (PEPSI) with increasing magnetic field strength (B(0)). Signal-to-noise ratio (SNR) per unit volume and unit time, and intrinsic linewidth (LW) of N-acetyl-aspartate (NAA), creatine (Cr), and choline (Cho) were measured with PEPSI at 1.5, 3, 4, and 7 Tesla on scanners that shared a similar software and hardware platform, using circularly polarized (CP) and eight-channel phased-array (PA) head coils. Data were corrected for relaxation effects and processed with a time-domain matched filter (MF) adapted to each B(0). The SNR and LW measured with PEPSI were very similar to those measured with conventional point-resolved spectroscopy (PRESS) SI. Measurements with the CP coil demonstrated a nearly linear SNR gain with respect to B(0) in central brain regions. For the PA coil, the SNR-B(0) relationship was less than linear, but there was a substantial SNR increase in comparison to the CP coil. The LW in units of ppm decreased with B(0), resulting in improved spectral resolution. These studies using PEPSI demonstrated linear gains in SNR with respect to B(0), consistent with theoretical expectations, and a decrease in ppm LW with increasing B(0).
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Tsai SY, Posse S, Lin YR, Ko CW, Otazo R, Chung HW, Lin FH. Fast mapping of theT2 relaxation time of cerebral metabolites using proton echo-planar spectroscopic imaging (PEPSI). Magn Reson Med 2007; 57:859-65. [PMID: 17457864 DOI: 10.1002/mrm.21225] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Metabolite T2 is necessary for accurate quantification of the absolute concentration of metabolites using long-echo-time (TE) acquisition schemes. However, lengthy data acquisition times pose a major challenge to mapping metabolite T2. In this study we used proton echo-planar spectroscopic imaging (PEPSI) at 3T to obtain fast T2 maps of three major cerebral metabolites: N-acetyl-aspartate (NAA), creatine (Cre), and choline (Cho). We showed that PEPSI spectra matched T2 values obtained using single-voxel spectroscopy (SVS). Data acquisition for 2D metabolite maps with a voxel volume of 0.95 ml (32 x 32 image matrix) can be completed in 25 min using five TEs and eight averages. A sufficient spectral signal-to-noise ratio (SNR) for T2 estimation was validated by high Pearson's correlation coefficients between logarithmic MR signals and TEs (R2 = 0.98, 0.97, and 0.95 for NAA, Cre, and Cho, respectively). In agreement with previous studies, we found that the T2 values of NAA, but not Cre and Cho, were significantly different between gray matter (GM) and white matter (WM; P < 0.001). The difference between the T2 estimates of the PEPSI and SVS scans was less than 9%. Consistent spatial distributions of T2 were found in six healthy subjects, and disagreement among subjects was less than 10%. In summary, the PEPSI technique is a robust method to obtain fast mapping of metabolite T2.
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Affiliation(s)
- Shang-Yueh Tsai
- Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan
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