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Hu SX, Xiao Y, Peng WL, Zeng W, Zhang Y, Zhang XY, Ling CT, Li HX, Xia CC, Li ZL. Accelerated 3D MR neurography of the brachial plexus using deep learning-constrained compressed sensing. Eur Radiol 2024; 34:842-851. [PMID: 37606664 DOI: 10.1007/s00330-023-09996-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/20/2023] [Accepted: 06/02/2023] [Indexed: 08/23/2023]
Abstract
OBJECTIVES To explore the use of deep learning-constrained compressed sensing (DLCS) in improving image quality and acquisition time for 3D MRI of the brachial plexus. METHODS Fifty-four participants who underwent contrast-enhanced imaging and forty-one participants who underwent unenhanced imaging were included. Sensitivity encoding with an acceleration of 2 × 2 (SENSE4x), CS with an acceleration of 4 (CS4x), and DLCS with acceleration of 4 (DLCS4x) and 8 (DLCS8x) were used for MRI of the brachial plexus. Apparent signal-to-noise ratios (aSNRs), apparent contrast-to-noise ratios (aCNRs), and qualitative scores on a 4-point scale were evaluated and compared by ANOVA and the Friedman test. Interobserver agreement was evaluated by calculating the intraclass correlation coefficients. RESULTS DLCS4x achieved higher aSNR and aCNR than SENSE4x, CS4x, and DLCS8x (all p < 0.05). For the root segment of the brachial plexus, no statistically significant differences in the qualitative scores were found among the four sequences. For the trunk segment, DLCS4x had higher scores than SENSE4x (p = 0.04) in the contrast-enhanced group and had higher scores than SENSE4x and DLCS8x in the unenhanced group (all p < 0.05). For the divisions, cords, and branches, DLCS4x had higher scores than SENSE4x, CS4x, and DLCS8x (all p ≤ 0.01). No overt difference was found among SENSE4x, CS4x, and DLCS8x in any segment of the brachial plexus (all p > 0.05). CONCLUSIONS In three-dimensional MRI for the brachial plexus, DLCS4x can improve image quality compared with SENSE4x and CS4x, and DLCS8x can maintain the image quality compared to SENSE4x and CS4x. CLINICAL RELEVANCE STATEMENT Deep learning-constrained compressed sensing can improve the image quality or accelerate acquisition of 3D MRI of the brachial plexus, which should be benefit in evaluating the brachial plexus and its branches in clinical practice. KEY POINTS •Deep learning-constrained compressed sensing showed higher aSNR, aCNR, and qualitative scores for the brachial plexus than SENSE and CS at the same acceleration factor with similar scanning time. •Deep learning-constrained compressed sensing at acceleration factor of 8 had comparable aSNR, aCNR, and qualitative scores to SENSE4x and CS4x with approximately half the examination time. •Deep learning-constrained compressed sensing may be helpful in clinical practice for improving image quality and acquisition time in three-dimensional MRI of the brachial plexus.
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Affiliation(s)
- Si-Xian Hu
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Yi Xiao
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Wan-Lin Peng
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Wen Zeng
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Yu Zhang
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Xiao-Yong Zhang
- Clinical Science, Philips Healthcare, Chengdu, Sichuan, China
| | - Chun-Tang Ling
- Clinical Science, Philips Healthcare, Chengdu, Sichuan, China
| | - Hai-Xia Li
- C&TS, Philips Healthcare, Guangzhou, Guangdong, China
| | - Chun-Chao Xia
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China.
| | - Zhen-Lin Li
- Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, 610041, Sichuan, China.
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Udayakumar D, Madhuranthakam AJ, Doğan BE. Magnetic Resonance Perfusion Imaging for Breast Cancer. Magn Reson Imaging Clin N Am 2024; 32:135-150. [PMID: 38007276 DOI: 10.1016/j.mric.2023.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
Breast cancer is the most frequently diagnosed cancer among women worldwide, carrying a significant socioeconomic burden. Breast cancer is a heterogeneous disease with 4 major subtypes identified. Each subtype has unique prognostic factors, risks, treatment responses, and survival rates. Advances in targeted therapies have considerably improved the 5-year survival rates for primary breast cancer patients largely due to widespread screening programs that enable early detection and timely treatment. Imaging techniques are indispensable in diagnosing and managing breast cancer. While mammography is the primary screening tool, MRI plays a significant role when mammography results are inconclusive or in patients with dense breast tissue. MRI has become standard in breast cancer imaging, providing detailed anatomic and functional data, including tumor perfusion and cellularity. A key characteristic of breast tumors is angiogenesis, a biological process that promotes tumor development and growth. Increased angiogenesis in tumors generally indicates poor prognosis and increased risk of metastasis. Dynamic contrast-enhanced (DCE) MRI measures tumor perfusion and serves as an in vivo metric for angiogenesis. DCE-MRI has become the cornerstone of breast MRI, boasting a high negative-predictive value of 89% to 99%, although its specificity can vary. This review presents a thorough overview of magnetic resonance (MR) perfusion imaging in breast cancer, focusing on the role of DCE-MRI in clinical applications and exploring emerging MR perfusion imaging techniques.
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Affiliation(s)
- Durga Udayakumar
- Department of Radiology, Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Ananth J Madhuranthakam
- Department of Radiology, Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Başak E Doğan
- Department of Radiology, Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA
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3
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Thakur U, Gulati V, Shah J, Tietze D, Chhabra A. Anterior cruciate ligament reconstruction related complications: 2D and 3D high-resolution magnetic resonance imaging evaluation. Skeletal Radiol 2022; 51:1347-1364. [PMID: 34977965 DOI: 10.1007/s00256-021-03982-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 02/02/2023]
Abstract
Anterior cruciate ligament (ACL) injury is a common indication for sports-related major surgery and accounts for a large proportion of ligamentous injuries in athletes. The advancements in 2D and 3D MR imaging have provided considerable potential for a one-stop shop radiation-free assessment with an all-in-one modality examination of the knee, for both soft-tissue and bone evaluations. This article reviews ACL injuries and types of surgical managements with illustrative examples using high resolution 2D and 3D MR imaging. Various complications of ACL reconstruction procedures are highlighted with a focus on the use of advanced MR imaging and relevant arthroscopic correlations.
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Affiliation(s)
- Uma Thakur
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Vaibhav Gulati
- Department of Radiology, Imaging Associates at National Heart Institute, New Delhi, India
| | - Jay Shah
- Department of Orthopaedic Surgery, UT Southwestern Medical Center, Dallas, Texas, USA
| | - David Tietze
- Department of Orthopaedic Surgery, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Avneesh Chhabra
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA. .,Department of Orthopaedic Surgery, UT Southwestern Medical Center, Dallas, Texas, USA.
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4
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Zhao Y, Yi Z, Liu Y, Chen F, Xiao L, Leong ATL, Wu EX. Calibrationless multi-slice Cartesian MRI via orthogonally alternating phase encoding direction and joint low-rank tensor completion. NMR IN BIOMEDICINE 2022; 35:e4695. [PMID: 35032072 DOI: 10.1002/nbm.4695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 10/06/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
We propose a multi-slice acquisition with orthogonally alternating phase encoding (PE) direction and subsequent joint calibrationless reconstruction for accelerated multiple individual 2D slices or multi-slice 2D Cartesian MRI. Specifically, multi-slice multi-channel data are first acquired with random or uniform PE undersampling while orthogonally alternating PE direction between adjacent slices. They are then jointly reconstructed through a recently developed low-rank multi-slice Hankel tensor completion (MS-HTC) approach. The proposed acquisition and reconstruction strategy was evaluated with human brain MR data. It effectively suppressed aliasing artifacts even at high acceleration factor, outperforming the existing MS-HTC approach, where PE direction is the same between adjacent slices. More importantly, the new strategy worked robustly with uniform undersampling or random undersampling without any consecutive central k-space lines. In summary, our proposed multi-slice MRI strategy exploits both coil sensitivity and image content similarities across adjacent slices. Orthogonally alternating PE direction among slices substantially facilitates the low-rank completion process and improves image reconstruction quality. This new strategy is applicable to uniform and random PE undersampling. It can be easily implemented in practice for Cartesian parallel imaging of multiple individual 2D slices without any coil sensitivity calibration.
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Affiliation(s)
- Yujiao Zhao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Zheyuan Yi
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, People's Republic of China
| | - Yilong Liu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Fei Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, People's Republic of China
| | - Linfang Xiao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Alex T L Leong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, People's Republic of China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, People's Republic of China
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Wang X, Udayakumar D, Xi Y, Rofsky NM, Pedrosa I, Madhuranthakam AJ. Single-shot RARE with Dixon: Application to robust abdominal imaging with uniform fat and water separation at 3T. Magn Reson Med 2021; 86:1463-1471. [PMID: 33929055 DOI: 10.1002/mrm.28816] [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: 08/08/2020] [Revised: 03/25/2021] [Accepted: 04/05/2021] [Indexed: 12/27/2022]
Abstract
PURPOSE To develop a true single shot turbo spin echo (SShTSE) acquisition with Dixon for robust T2 -weighted abdominal imaging with uniform fat and water separation at 3T. METHODS The in-phase (IP) and out-of-phase (OP) echoes for Dixon processing were acquired in the same repetition time of a SShTSE using partial echoes. A phase-preserved bi-directional homodyne reconstruction was developed to compensate the partial echo and the partial phase encoding of SShTSE. With IRB approval, the SShTSE-Dixon was compared against standard SShTSE, without and with fat suppression using spectral adiabatic inversion recovery (SPAIR) in 5 healthy volunteers and 5 patients. The SNR and contrast ratio (CR) of spleen to liver were compared among different acquisitions. RESULTS The bi-directional homodyne reconstruction successfully minimized ringing artifacts because of partial acquisitions. SShTSE-Dixon achieved uniform fat suppression compared to SShTSE-SPAIR with fat suppression failures of 1/10 versus 10/10 in the axial plane and 0/5 versus 5/5 in the coronal plane, respectively. The SNRs of the liver (12.2 ± 4.9 vs. 11.7 ± 5.2; P = .76) and spleen (25.9 ± 11.6 vs. 23.7 ± 9.7; P = .14) were equivalent between fat-suppressed images (SShTSE-Dixon water-only and SShTSE-SPAIR). The SNRs of liver (14.4 ± 5.7 vs. 13.4 ± 5.0; P = .60) and spleen (26.5 ± 10.1 vs. 25.7 ± 8.5; P = .56) were equivalent between non-fat-suppressed images (SShTSE-Dixon IP and SShTSE). The CRs of spleen to liver were also similar between fat-suppressed images (2.6 ± 0.4 vs. 2.5 ± 0.5; P =.92) and non-fat-suppressed images (2.3 ± 0.6 vs. 2.2 ± 0.4; P =.84). CONCLUSION SShTSE-Dixon generates robust abdominal T2 -weighted images at 3T with and without uniform fat suppression, along with perfectly co-registered fat-only images in a single acquisition.
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Affiliation(s)
- Xinzeng Wang
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.,Global MR Application and Workflow, GE Healthcare, Houston, Texas, USA
| | - Durga Udayakumar
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.,Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Yin Xi
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.,Population and Data Sciences, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Neil M Rofsky
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.,Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Ivan Pedrosa
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.,Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Ananth J Madhuranthakam
- Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.,Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
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Agha O, Diaz A, Davies M, Kim HT, Liu X, Feeley BT. Rotator cuff tear degeneration and the role of fibro-adipogenic progenitors. Ann N Y Acad Sci 2020; 1490:13-28. [PMID: 32725671 DOI: 10.1111/nyas.14437] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/06/2020] [Accepted: 06/18/2020] [Indexed: 12/25/2022]
Abstract
The high prevalence of rotator cuff tears poses challenges to individual patients and the healthcare system at large. This orthopedic injury is complicated further by high rates of retear after surgical repair. Outcomes following repair are highly dependent upon the quality of the injured rotator cuff muscles, and it is, therefore, crucial that the pathophysiology of rotator cuff degeneration continues to be explored. Fibro-adipogenic progenitors, a major population of resident muscle stem cells, have emerged as the main source of intramuscular fibrosis and fatty infiltration, both of which are key features of rotator cuff muscle degeneration. Improvements to rotator cuff repair outcomes will likely require addressing the muscle pathology produced by these cells. The aim of this review is to summarize the current rotator cuff degeneration assessment tools, the effects of poor muscle quality on patient outcomes, the role of fibro-adipogenic progenitors in mediating muscle pathology, and how these cells could be leveraged for potential therapeutics to augment current rotator cuff surgical and rehabilitative strategies.
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Affiliation(s)
- Obiajulu Agha
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California.,San Francisco Veteran Affairs Health Care System, San Francisco, California
| | - Agustin Diaz
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California.,San Francisco Veteran Affairs Health Care System, San Francisco, California
| | - Michael Davies
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California.,San Francisco Veteran Affairs Health Care System, San Francisco, California
| | - Hubert T Kim
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California.,San Francisco Veteran Affairs Health Care System, San Francisco, California
| | - Xuhui Liu
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California.,San Francisco Veteran Affairs Health Care System, San Francisco, California
| | - Brian T Feeley
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California.,San Francisco Veteran Affairs Health Care System, San Francisco, California
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7
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Bastian‐Jordan M, Dhupelia S, McMeniman M, Lanham M, Hislop‐Jambrich J. A quality audit of MRI knee exams with the implementation of a novel 2-point DIXON sequence. J Med Radiat Sci 2019; 66:163-169. [PMID: 31353806 PMCID: PMC6745386 DOI: 10.1002/jmrs.350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION The objective of this study was to evaluate the effect on diagnostic image quality and acquisition time utilising a DIXON sequence to replace two standard proton density (PD) fat saturation (FS) sequences in routine magnetic resonance (MR) evaluation of the knee. METHODS Thirty-one consecutive patients referred for an MR examination of the knee were examined using the routine departmental protocol along with the addition of a DIXON sequence. The sequences were all evaluated by a senior radiologist and feedback provided via both written and scored responses. The sequences were then repackaged for two additional reviewers with the sagittal PD FS (Chemical Shift Selective Fat Saturation or CHESS) and sagittal PD removed and replaced with the DIXON (fat suppressed and in-phase, respectively) sequence equivalents. Scored and written responses were tabled and reviewed to assess the suitability of sequence replacement. RESULTS The DIXON-based images were judged as being comparable replacements for the sagittal PD fat sat and PD sequences. There was no report of any loss in diagnostic confidence across the 31 patients (total of 32 knees) with a time saving of just over 10% gained. The most common issues raised affecting image quality, though not affecting diagnostic attributes, were patient motion and a minor chemical shift artefact. CONCLUSION The use of the DIXON technique in place of the PD sequences was of equivalent diagnostic quality with'good' to 'outstanding' fat suppression observed for the majority of cases using the DIXON sequence with an incremental time saving obtained.
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Affiliation(s)
- Matthew Bastian‐Jordan
- QLD X‐rayQEII Hospital, Coopers PlainsBrisbaneQueenslandAustralia
- University of QueenslandBrisbaneQueenslandAustralia
| | - Sanjay Dhupelia
- University of QueenslandBrisbaneQueenslandAustralia
- QLD X‐rayGreenslopes Private HospitalBrisbaneQueenslandAustralia
| | | | - Matthew Lanham
- QLD X‐rayQEII Hospital, Coopers PlainsBrisbaneQueenslandAustralia
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Mootz AR, Madhuranthakam AJ, Doğan B. Changing Paradigms in Breast Cancer Screening: Abbreviated Breast MRI. Eur J Breast Health 2019; 15:1-6. [PMID: 30816364 DOI: 10.5152/ejbh.2018.4402] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/02/2018] [Indexed: 01/07/2023]
Abstract
Breast magnetic resonance imaging (MRI) is the most sensitive imaging method for breast cancer detection. In this review we discuss the vastly superior performance of MRI compared to traditional breast cancer screening modalities of mammography, tomosynthesis and ultrasound. We discuss an abbreviated breast MRI (AB-MRI) protocol utilizing Dixon sequences which is compliant with American College of Radiology (ACR) guidelines for accreditation of breast MRI but with significantly reduced scan times. Adaptation of such an AB-MRI protocol significantly increases patient throughput and may allow MRI to serve as a stand- alone breast cancer screening tool.
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Affiliation(s)
- Ann R Mootz
- Department of Radiology, University of Texas Southwestern Medical School, Texas, USA
| | | | - Başak Doğan
- Department of Radiology, University of Texas Southwestern Medical School, Texas, USA
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9
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Wang X, Greer JS, Dimitrov IE, Pezeshk P, Chhabra A, Madhuranthakam AJ. Frequency Offset Corrected Inversion Pulse for B 0 and B 1 Insensitive Fat Suppression at 3T: Application to MR Neurography of Brachial Plexus. J Magn Reson Imaging 2018; 48:1104-1111. [PMID: 30218576 DOI: 10.1002/jmri.26021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 03/07/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The 3D short tau inversion recovery (STIR) sequence is routinely used in clinical MRI to achieve robust fat suppression. However, the performance of the commonly used adiabatic inversion pulse, hyperbolic secant (HS), is compromised in challenging areas with increased B0 and B1 inhomogeneities, such as brachial plexus at 3T. PURPOSE To demonstrate the frequency offset corrected inversion (FOCI) pulse as an efficient fat suppression STIR pulse with increased robustness to B0 and B1 inhomogeneities at 3T, compared to the HS pulse. STUDY TYPE Prospective. SUBJECTS/PHANTOM Initial evaluation was performed in phantoms and one healthy volunteer by varying the B1 field, while subsequent comparison was performed in three healthy volunteers and five patients without varying the B1 . FIELD STRENGTH/SEQUENCE 3T; 3D TSE-STIR with HS and FOCI pulses. ASSESSMENT Brachial plexus images were qualitatively evaluated by two musculoskeletal radiologists independently using a four-point grading scale for fat suppression, shading artifacts, and nerve visualization. STATISTICAL TEST The Wilcoxon signed-rank test with P < 0.05 was considered statistically significant. RESULTS Simulations and phantom experiments demonstrated broader bandwidth (2.5 kHz vs. 0.83 kHz, increased B0 robustness) at the same adiabatic threshold and lower adiabatic threshold (5 μT vs. 7 μT at 3.5 ppm, increased B1 robustness) at the same bandwidth with the FOCI pulse compared to the HS pulse With increased bandwidth, the FOCI pulse achieved robust fat suppression even at 50% of maximum B1 strength, while the HS pulse required >75% of maximum B1 strength. Compared to the standard 3D TSE-STIR with HS pulse, the FOCI pulse achieved uniform fat suppression (P < 0.05), better nerve visualization (P < 0.05), and minimal shading artifacts (P < 0.01) in brachial plexus at 3T. DATA CONCLUSION The FOCI pulse has increased robustness to B0 and B1 inhomogeneities, compared to the HS pulse, and enables uniform fat suppression in brachial plexus at 3T. LEVEL OF EVIDENCE 1 Techinical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;48:1104-1111.
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Affiliation(s)
- Xinzeng Wang
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Joshua S Greer
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Bioengineering, University of Texas at Dallas, Richardson, Texas, USA
| | - Ivan E Dimitrov
- Philips Medical Systems, Gainesville, Florida, USA.,Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Parham Pezeshk
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Avneesh Chhabra
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Orthopedic Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ananth J Madhuranthakam
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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10
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Khosa F, Clough RE, Wang X, Madhuranthakam AJ, Greenman RL. The potential role of IDEAL MRI for identification of lipids and hemorrhage in carotid artery plaques. Magn Reson Imaging 2018; 49:25-31. [DOI: 10.1016/j.mri.2017.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 12/03/2017] [Indexed: 02/06/2023]
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11
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Pezeshk P, Alian A, Chhabra A. Role of chemical shift and Dixon based techniques in musculoskeletal MR imaging. Eur J Radiol 2017; 94:93-100. [DOI: 10.1016/j.ejrad.2017.06.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 12/25/2022]
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12
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Chhabra A, Madhuranthakam AJ, Andreisek G. Magnetic resonance neurography: current perspectives and literature review. Eur Radiol 2017; 28:698-707. [PMID: 28710579 DOI: 10.1007/s00330-017-4976-8] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 05/14/2017] [Accepted: 06/29/2017] [Indexed: 12/19/2022]
Abstract
Magnetic resonance neurography (also called MRN or MR neurography) refers to MR imaging dedicated to the peripheral nerves. It is a technique that enhances selective multiplanar visualisation of the peripheral nerve and pathology by encompassing a combination of two-dimensional, three-dimensional and diffusion imaging pulse sequences. Referring physicians who seek imaging techniques that can depict and diagnose peripheral nerve pathologies superior to conventional MR imaging are driving the demand for MRN. This article reviews the pathophysiology of peripheral nerves in common practice scenarios, technical considerations of MRN, current indications of MRN, normal and abnormal neuromuscular appearances, and imaging pitfalls. Finally, the emerging utility of diffusion-weighted and diffusion tensor imaging is discussed and future directions are highlighted. KEY POINTS • Lesion relationship to neural architecture is more conspicuous on MRN than MRI. • 3D multiplanar imaging technique is essential for pre-surgical planning. • Nerve injuries can be classified on MRN using Sunderland's classification. • DTI provides quantitative information and insight into intraneural integrity and pathophysiology.
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Affiliation(s)
- Avneesh Chhabra
- Radiology and Orthopedic Surgery and Musculoskeletal Radiology, UT Southwestern Medical Center, Dallas, TX, USA.
- Adjunct Faculty, Johns Hopkins University, Baltimore, MD, USA.
| | - Ananth J Madhuranthakam
- Department of Radiology and Advanced Imaging Research Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Gustav Andreisek
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zürich, Switzerland
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13
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Wang X, Harrison C, Mariappan YK, Gopalakrishnan K, Chhabra A, Lenkinski RE, Madhuranthakam AJ. MR Neurography of Brachial Plexus at 3.0 T with Robust Fat and Blood Suppression. Radiology 2017; 283:538-546. [DOI: 10.1148/radiol.2016152842] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Xinzeng Wang
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
| | - Crystal Harrison
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
| | - Yogesh K. Mariappan
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
| | - Karthik Gopalakrishnan
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
| | - Avneesh Chhabra
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
| | - Robert E. Lenkinski
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
| | - Ananth J. Madhuranthakam
- From the Department of Radiology (X.W., C.E.H., A.C., R.E.L., A.J.M.) and Advanced Imaging Research Center (A.C., R.E.L., A.J.M.), UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75019-9061; and Philips Healthcare, Philips Innovation Campus, Bangalore, India (Y.K.M., K.G.)
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Kim H, Kim DH, Sohn CH, Park J. Rapid chemical shift encoding with single-acquisition single-slab 3D GRASE. Magn Reson Med 2017; 78:1852-1861. [DOI: 10.1002/mrm.26595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/08/2016] [Accepted: 12/08/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Hahnsung Kim
- Department of Biomedical Engineering; Sungkyunkwan University; Suwon Republic of Korea
- Department of Electrical and Electronic Engineering; Yonsei University; Seoul Republic of Korea
| | - Dong-Hyun Kim
- Department of Electrical and Electronic Engineering; Yonsei University; Seoul Republic of Korea
| | - Chul-Ho Sohn
- Department of Radiology; Seoul National University Hospital; Seoul Republic of Korea
| | - Jaeseok Park
- Department of Biomedical Engineering; Sungkyunkwan University; Suwon Republic of Korea
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Faster pediatric 3-T abdominal magnetic resonance imaging: comparison between conventional and variable refocusing flip-angle single-shot fast spin-echo sequences. Pediatr Radiol 2015; 45:847-54. [PMID: 25433510 PMCID: PMC4449830 DOI: 10.1007/s00247-014-3227-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/17/2014] [Accepted: 10/30/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Single-shot fast spin echo (SSFSE) is particularly appealing in pediatric patients because of its motion robustness. However radiofrequency energy deposition at 3 tesla forces long pauses between slices, leading to longer scans, longer breath-holds and more between-slice motion. OBJECTIVE We sought to learn whether modulation of the SSFSE refocusing flip-angle train could reduce radiofrequency energy deposition without degrading image quality, thereby reducing inter-slice pauses and overall scan times. MATERIALS AND METHODS We modulated the refocusing flip-angle train for SSFSE to minimize energy deposition while minimizing blurring and motion-related signal loss. In a cohort of 50 consecutive patients (25 boys, mean age 5.5 years, range 1 month to 17 years) referred for abdominal MRI we obtained standard SSFSE and variable refocusing flip-angle (vrfSSFSE) images and recorded sequence scan times. Two readers independently scored the images in blinded, randomized order for noise, tissue contrast, sharpness, artifacts and left lobe hepatic signal uniformity on a four-point scale. The null hypothesis of no difference between SSFSE and vrfSSFSE image-quality was assessed with a Mann-Whitney U test, and the null hypothesis of no scan time difference was assessed with the paired t-test. RESULTS SSFSE and vrfSSFSE mean acquisition times were 54.3 and 26.2 s, respectively (P-value <0.0001). For each reader, SSFSE and vrfSSFSE noise, tissue contrast, sharpness and artifacts were not significantly different (P-values 0.18-0.86). However, SSFSE had better left lobe hepatic signal uniformity (P < 0.01, both readers). CONCLUSION vrfSSFSE is twice as fast as SSFSE, with equivalent image quality with the exception of left hepatic lobe signal heterogeneity.
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Dong J, Liu T, Chen F, Zhou D, Dimov A, Raj A, Cheng Q, Spincemaille P, Wang Y. Simultaneous phase unwrapping and removal of chemical shift (SPURS) using graph cuts: application in quantitative susceptibility mapping. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:531-540. [PMID: 25312917 DOI: 10.1109/tmi.2014.2361764] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Quantitative susceptibility mapping (QSM) is a magnetic resonance imaging technique that reveals tissue magnetic susceptibility. It relies on having a high quality field map, typically acquired with a relatively long echo spacing and long final TE. Applications of QSM outside the brain require the removal of fat contributions to the total signal phase. However, current water/fat separation methods applied on typical data acquired for QSM suffer from three issues: inadequacy when using large echo spacing, over-smoothing of the field maps and high computational cost. In this paper, the general phase wrap and chemical shift problem is formulated using a single species fitting and is solved using graph cuts with conditional jump moves. This method is referred as simultaneous phase unwrapping and removal of chemical shift (SPURS). The result from SPURS is then used as the initial guess for a voxel-wise iterative decomposition of water and fat with echo asymmetric and least-squares estimation (IDEAL). The estimated 3-D field maps are used to compute QSM in body regions outside of the brain, such as the liver. Experimental results show substantial improvements in field map estimation, water/fat separation and reconstructed QSM compared to two existing water/fat separation methods on 1.5T and 3T magnetic resonance human data with long echo spacing and rapid field map variation.
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17
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Rosado-Toro JA, Barr T, Galons JP, Marron MT, Stopeck A, Thomson C, Thompson P, Carroll D, Wolf E, Altbach MI, Rodríguez JJ. Automated breast segmentation of fat and water MR images using dynamic programming. Acad Radiol 2015; 22:139-48. [PMID: 25572926 PMCID: PMC4366060 DOI: 10.1016/j.acra.2014.09.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 09/23/2014] [Accepted: 09/26/2014] [Indexed: 11/18/2022]
Abstract
RATIONALE AND OBJECTIVES To develop and test an algorithm that outlines the breast boundaries using information from fat and water magnetic resonance images. MATERIALS AND METHODS Three algorithms were implemented and tested using registered fat and water magnetic resonance images. Two of the segmentation algorithms are simple extensions of the techniques used for contrast-enhanced images: one algorithm uses clustering and local gradient (CLG) analysis and the other algorithm uses a Hessian-based sheetness filter (HSF). The third segmentation algorithm uses k-means++ and dynamic programming (KDP) for finding the breast pixels. All three algorithms separate the left and right breasts using either a fixed region or a morphological method. The performance is quantified using a mutual overlap (Dice) metric and a pectoral muscle boundary error. The algorithms are evaluated against three manual tracers using 266 breast images from 14 female subjects. RESULTS The KDP algorithm has a mean overlap percentage improvement that is statistically significant relative to the HSF and CLG algorithms. When using a fixed region to remove the tissue between breasts with tracer 1 as a reference, the KDP algorithm has a mean overlap of 0.922 compared to 0.864 (P < .01) for HSF and 0.843 (P < .01) for CLG. The performance of KDP is very similar to tracers 2 (0.926 overlap) and 3 (0.929 overlap). The performance analysis in terms of pectoral muscle boundary error showed that the fraction of the muscle boundary within three pixels of reference tracer 1 is 0.87 using KDP compared to 0.578 for HSF and 0.617 for CLG. Our results show that the performance of the KDP algorithm is independent of breast density. CONCLUSIONS We developed a new automated segmentation algorithm (KDP) to isolate breast tissue from magnetic resonance fat and water images. KDP outperforms the other techniques that focus on local analysis (CLG and HSF) and yields a performance similar to human tracers.
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Affiliation(s)
- José A Rosado-Toro
- Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721
| | - Tomoe Barr
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721
| | | | | | - Alison Stopeck
- Arizona Cancer Center, Tucson, Arizona 85721; Department of Medicine, University of Arizona, Tucson, Arizona 85724
| | | | - Patricia Thompson
- Arizona Cancer Center, Tucson, Arizona 85721; Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85721
| | - Danielle Carroll
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724
| | - Eszter Wolf
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724
| | - María I Altbach
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724.
| | - Jeffrey J Rodríguez
- Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721
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18
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Eggers H, Börnert P. Chemical shift encoding-based water-fat separation methods. J Magn Reson Imaging 2014; 40:251-68. [PMID: 24446249 DOI: 10.1002/jmri.24568] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 12/12/2013] [Indexed: 12/13/2022] Open
Abstract
The suppression of signal from fat constitutes a basic requirement in many applications of magnetic resonance imaging. To date, this is predominantly achieved during data acquisition, using fat saturation, inversion recovery, or water excitation methods. Postponing the separation of signal from water and fat until image reconstruction holds the promise of resolving some of the problems associated with these methods, such as failure in the presence of field inhomogeneities or contrast agents. In this article, methods are reviewed that rely on the difference in chemical shift between the hydrogen atoms in water and fat to perform such a retrospective separation. The basic principle underlying these so-called Dixon methods is introduced, and some fundamental implementations of the required chemical shift encoding in the acquisition and the subsequent water-fat separation in the reconstruction are described. Practical issues, such as the selection of key parameters and the appearance of typical artifacts, are illustrated, and a broad range of applications is demonstrated, including abdominal, cardiovascular, and musculoskeletal imaging. Finally, advantages and disadvantages of these Dixon methods are summarized, and emerging opportunities arising from the availability of information on the amount and distribution of fat are discussed.
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Pokharel SS, Macura KJ, Kamel IR, Zaheer A. Current MR imaging lipid detection techniques for diagnosis of lesions in the abdomen and pelvis. Radiographics 2014; 33:681-702. [PMID: 23674769 DOI: 10.1148/rg.333125068] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
One application of the unique capability of magnetic resonance (MR) imaging for characterizing soft tissues is in the specific detection of lipid. Adipose tissue may be abundant in the body, but its presence in a lesion can greatly limit differential diagnostic considerations. This article reviews MR imaging fat detection techniques and discusses lesions in the abdomen and pelvis that can be readily diagnosed by using these techniques. Traditional fat detection methods include inversion-recovery and chemically selective fat-suppression pulse sequences, with the former being less sensitive to field heterogeneity and less tissue specific than the latter. Chemical shift-based sequences, which exploit the inherent resonance frequency difference between lipid and water to depict intracytoplasmic fat, have great utility for evaluating hepatic steatosis and lesions such as adrenal and hepatic adenomas, hepatocellular carcinoma, focal lipomatosis of the pancreas, and adrenal cortical carcinoma. The signal from large amounts of fat can be suppressed by using a narrow radiofrequency pulse for selective excitation of fat protons (ie, fat saturation imaging), a technique that increases image contrast resolution and highlights lesions such as contrast-enhancing tissue, edema, and blood products. This technique is especially useful for evaluating renal angiomyolipomas, adrenal myelolipomas, ovarian teratomas, and liposarcomas. MR spectroscopy is a promising method for quantifying absolute liver fat concentration and changes in hepatic triglyceride content during treatment. New and evolving techniques include magnetization transfer and modified Dixon sequences. A solid understanding of these techniques will help improve the interpretation of abdominal and pelvic imaging studies.
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Affiliation(s)
- Sajal S Pokharel
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD 21287, USA
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20
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Mugler JP. Optimized three‐dimensional fast‐spin‐echo MRI. J Magn Reson Imaging 2014; 39:745-67. [PMID: 24399498 DOI: 10.1002/jmri.24542] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/31/2013] [Indexed: 11/10/2022] Open
Affiliation(s)
- John P. Mugler
- Department of Radiology and Medical ImagingUniversity of Virginia School of MedicineCharlottesville Virginia USA
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Moran CJ, Hargreaves BA, Saranathan M, Lipson JA, Kao J, Ikeda DM, Daniel BL. 3D T2-weighted spin echo imaging in the breast. J Magn Reson Imaging 2013; 39:332-8. [PMID: 23596017 DOI: 10.1002/jmri.24151] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 03/04/2013] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To evaluate the performance of 2D versus 3D T2-weighted spin echo imaging in the breast. MATERIALS AND METHODS 2D and 3D T2-weighted images were acquired in 25 patients as part of a clinically indicated breast magnetic resonance imaging (MRI) exam. Lesion-to-fibroglandular tissue signal ratio was measured in 16 identified lesions. Clarity of lesion morphology was assessed through a blinded review by three radiologists. Instances demonstrating the potential diagnostic contribution of 3D versus 2D T2-weighted imaging in the breast were noted through unblinded review by a fourth radiologist. RESULTS The lesion-to-fibroglandular tissue signal ratio was well correlated between 2D and 3D T2-weighted images (R(2) = 0.93). Clarity of lesion morphology was significantly better with 3D T2-weighted imaging for all observers based on a McNemar test (P ≤ 0.02, P ≤ 0.01, P ≤ 0.03). Instances indicating the potential diagnostic contribution of 3D T2-weighted imaging included improved depiction of signal intensity and improved alignment between DCE and T2-weighted findings. CONCLUSION In this pilot study, 3D T2-weighted imaging provided comparable contrast and improved depiction of lesion morphology in the breast in comparison to 2D T2-weighted imaging. Based on these results further investigation to determine the diagnostic impact of 3D T2-weighted imaging in breast MRI is warranted.
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Affiliation(s)
- Catherine J Moran
- Department of Radiology, Stanford University, Stanford, California, USA
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Moran CJ, Brodsky EK, Bancroft LH, Reeder SB, Yu H, Kijowski R, Engel D, Block WF. High-resolution 3D radial bSSFP with IDEAL. Magn Reson Med 2013; 71:95-104. [PMID: 23504943 DOI: 10.1002/mrm.24633] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 12/16/2012] [Accepted: 12/18/2012] [Indexed: 12/19/2022]
Abstract
Radial trajectories facilitate high-resolution balanced steady state free precession (bSSFP) because the efficient gradients provide more time to extend the trajectory in k-space. A number of radial bSSFP methods that support fat-water separation have been developed; however, most of these methods require an environment with limited B0 inhomogeneity. In this work, high-resolution bSSFP with fat-water separation is achieved in more challenging B0 environments by combining a 3D radial trajectory with the IDEAL chemical species separation method. A method to maintain very high resolution within the timing constraints of bSSFP and IDEAL is described using a dual-pass pulse sequence. The sampling of a unique set of radial lines at each echo time is investigated as a means to circumvent the longer scan time that IDEAL incurs as a multiecho acquisition. The manifestation of undersampling artifacts in this trajectory and their effect on chemical species separation are investigated in comparison to the case in which each echo samples the same set of radial lines. This new bSSFP method achieves 0.63 mm isotropic resolution in a 5-min scan and is demonstrated in difficult in vivo imaging environments, including the breast and a knee with ACL reconstruction hardware at 1.5 T.
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Affiliation(s)
- Catherine J Moran
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
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23
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Hindman N, Ngo L, Genega EM, Melamed J, Wei J, Braza JM, Rofsky NM, Pedrosa I. Angiomyolipoma with minimal fat: can it be differentiated from clear cell renal cell carcinoma by using standard MR techniques? Radiology 2012; 265:468-77. [PMID: 23012463 DOI: 10.1148/radiol.12112087] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE To retrospectively assess whether magnetic resonance (MR) imaging with opposed-phase and in-phase gradient-echo (GRE) sequences and MR feature analysis can differentiate angiomyolipomas (AMLs) that contain minimal fat from clear cell renal cell carcinomas (RCCs), with particular emphasis on small (<3-cm) masses. MATERIALS AND METHODS Institutional review board approval and a waiver of informed consent were obtained for this HIPAA-compliant study. MR images from 108 pathologically proved renal masses (88 clear cell RCCs and 20 minimal fat AMLs from 64 men and 44 women) at two academic institutions were evaluated. The signal intensity (SI) of each renal mass and spleen on opposed-phase and in-phase GRE images was used to calculate an SI index and tumor-to-spleen SI ratio. Two radiologists who were blinded to the pathologic results independently assessed the subjective presence of intravoxel fat (ie, decreased SI on opposed-phase images compared with that on in-phase images), SI on T1-weighted and T2-weighted images, cystic degeneration, necrosis, hemorrhage, retroperitoneal collaterals, and renal vein thrombosis. Results were analyzed by using the Wilcoxon rank sum test, two-tailed Fisher exact test, and multivariate logistic regression analysis for all renal masses and for small masses. A P value of less than .05 was considered to indicate a statistically significant difference. RESULTS There were no differences between minimal fat AMLs and clear cell RCCs for the SI index (8.05%±14.46 vs 14.99%±19.9; P=.146) or tumor-to-spleen ratio (-8.96%±16.6 and -15.8%±22.4; P=.227) when all masses or small masses were analyzed. Diagnostic accuracy (area under receiver operating characteristic curve) for the SI index and tumor-to-spleen ratio was 0.59. Intratumoral necrosis and larger size were predictive of clear cell RCC (P<.001) for all lesions, whereas low SI (relative to renal parenchyma SI) on T2-weighted images, smaller size, and female sex correlated with minimal fat AML (P<.001) for all lesions. CONCLUSION The diagnostic accuracy of opposed-phase and in-phase GRE MR imaging for the differentiation of minimal fat AML and clear cell RCC is poor. In this cohort, low SI on T2-weighted images relative to renal parenchyma and small size suggested minimal fat AML, whereas intratumoral necrosis and large size argued against this diagnosis.
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Affiliation(s)
- Nicole Hindman
- Department of Radiology, New York University Langone Medical Center, New York, NY, USA
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24
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Madhuranthakam AJ, Smith MP, Yu H, Shimakawa A, Reeder SB, Rofsky NM, McKenzie CA, Brittain JH. Water-silicone separated volumetric MR acquisition for rapid assessment of breast implants. J Magn Reson Imaging 2012; 35:1216-21. [DOI: 10.1002/jmri.22872] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 10/04/2011] [Indexed: 11/11/2022] Open
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25
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McMahon CJ, Madhuranthakam AJ, Wu JS, Yablon CM, Wei JL, Rofsky NM, Hochman MG. High-resolution proton density weighted three-dimensional fast spin echo (3D-FSE) of the knee with IDEAL at 1.5 tesla: Comparison with 3D-FSE and 2D-FSE-initial experience. J Magn Reson Imaging 2011; 35:361-9. [DOI: 10.1002/jmri.22829] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Accepted: 09/08/2011] [Indexed: 11/08/2022] Open
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Volumetric fat-water separated T2-weighted MRI. Pediatr Radiol 2011; 41:875-83. [PMID: 21243349 DOI: 10.1007/s00247-010-1963-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 11/22/2010] [Accepted: 12/01/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND Pediatric body MRI exams often cover multiple body parts, making the development of broadly applicable protocols and obtaining uniform fat suppression a challenge. Volumetric T2 imaging with Dixon-type fat-water separation might address this challenge, but it is a lengthy process. OBJECTIVE We develop and evaluate a faster two-echo approach to volumetric T2 imaging with fat-water separation. MATERIALS AND METHODS A volumetric spin-echo sequence was modified to include a second shifted echo so two image sets are acquired. A region-growing reconstruction approach was developed to decompose separate water and fat images. Twenty-six children were recruited with IRB approval and informed consent. Fat-suppression quality was graded by two pediatric radiologists and compared against conventional fat-suppressed fast spin-echo T2-W images. Additionally, the value of in- and opposed-phase images was evaluated. RESULTS Fat suppression on volumetric images had high quality in 96% of cases (95% confidence interval of 80-100%) and were preferred over or considered equivalent to conventional two-dimensional fat-suppressed FSE T2 imaging in 96% of cases (95% confidence interval of 78-100%). In- and opposed-phase images had definite value in 12% of cases. CONCLUSION Volumetric fat-water separated T2-weighted MRI is feasible and is likely to yield improved fat suppression over conventional fat-suppressed T2-weighted imaging.
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Abstract
Magnetic resonance (MR) imaging is one of the most commonly used imaging modality for evaluating patients with joint pain. Musculoskeletal MR protocols at most institutions consist of 2-dimensional fast spin echo (FSE) sequences repeated in multiple planes. Three-dimensional sequences have also been used to evaluate the musculoskeletal system and have many potential advantages over 2-dimensional FSE sequences. Three-dimensional sequences acquire thin continuous slices through joints with high in-plane spatial resolution, which minimize the effects of partial volume averaging. Newly developed 3-dimensional isotropic resolution sequences can also be used to create high-quality multiplanar reformat images that allow joints to be evaluated in any orientation after a single acquisition. Preliminary results on the use of 3-dimensional isotropic resolution sequences for evaluating the musculoskeletal system are encouraging. However, additional studies are needed to document the advantages of 3-dimensional sequences before they can replace currently used 2-dimensional FSE sequences for evaluating the musculoskeletal system in clinical practice.
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Affiliation(s)
- Richard Kijowski
- University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
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