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Wang Q, Zhao W, Xing X, Wang Y, Xin P, Chen Y, Zhu Y, Xu J, Zhao Q, Yuan H, Lang N. Feasibility of AI-assisted compressed sensing protocols in knee MR imaging: a prospective multi-reader study. Eur Radiol 2023; 33:8585-8596. [PMID: 37382615 PMCID: PMC10667384 DOI: 10.1007/s00330-023-09823-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/02/2023] [Accepted: 03/22/2023] [Indexed: 06/30/2023]
Abstract
OBJECTIVES To evaluate the image quality and diagnostic performance of AI-assisted compressed sensing (ACS) accelerated two-dimensional fast spin-echo MRI compared with standard parallel imaging (PI) in clinical 3.0T rapid knee scans. METHODS This prospective study enrolled 130 consecutive participants between March and September 2022. The MRI scan procedure included one 8.0-min PI protocol and two ACS protocols (3.5 min and 2.0 min). Quantitative image quality assessments were performed by evaluating edge rise distance (ERD) and signal-to-noise ratio (SNR). Shapiro-Wilk tests were performed and investigated by the Friedman test and post hoc analyses. Three radiologists independently evaluated structural disorders for each participant. Fleiss κ analysis was used to compare inter-reader and inter-protocol agreements. The diagnostic performance of each protocol was investigated and compared by DeLong's test. The threshold for statistical significance was set at p < 0.05. RESULTS A total of 150 knee MRI examinations constituted the study cohort. For the quantitative assessment of four conventional sequences with ACS protocols, SNR improved significantly (p < 0.001), and ERD was significantly reduced or equivalent to the PI protocol. For the abnormality evaluated, the intraclass correlation coefficient ranged from moderate to substantial between readers (κ = 0.75-0.98) and between protocols (κ = 0.73-0.98). For meniscal tears, cruciate ligament tears, and cartilage defects, the diagnostic performance of ACS protocols was considered equivalent to PI protocol (Delong test, p > 0.05). CONCLUSIONS Compared with the conventional PI acquisition, the novel ACS protocol demonstrated superior image quality and was feasible for achieving equivalent detection of structural abnormalities while reducing acquisition time by half. CLINICAL RELEVANCE STATEMENT Artificial intelligence-assisted compressed sensing (ACS) providing excellent quality and a 75% reduction in scanning time presents significant clinical advantages in improving the efficiency and accessibility of knee MRI for more patients. KEY POINTS • The prospective multi-reader study showed no difference in diagnostic performance between parallel imaging and AI-assisted compression sensing (ACS) was found. • Reduced scan time, sharper delineation, and less noise with ACS reconstruction. • Improved efficiency of the clinical knee MRI examination by the ACS acceleration.
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Affiliation(s)
- Qizheng Wang
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Weili Zhao
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Xiaoying Xing
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Ying Wang
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Peijin Xin
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Yongye Chen
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Yupeng Zhu
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Jiajia Xu
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Qiang Zhao
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Huishu Yuan
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China
| | - Ning Lang
- Department of Radiology, Peking University Third Hospital, Haidian District, 49 North Garden Road, Beijing, 100191, People's Republic of China.
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Lee EJ, Hwang J, Park S, Bae SH, Lim J, Chang YW, Hong SS, Oh E, Nam BD, Jeong J, Sung JK, Nickel D. Utility of accelerated T2-weighted turbo spin-echo imaging with deep learning reconstruction in female pelvic MRI: a multi-reader study. Eur Radiol 2023; 33:7697-7706. [PMID: 37314472 DOI: 10.1007/s00330-023-09781-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/24/2023] [Accepted: 03/28/2023] [Indexed: 06/15/2023]
Abstract
OBJECTIVES To determine the clinical feasibility of T2-weighted turbo spin-echo (T2-TSE) imaging with deep learning reconstruction (DLR) in female pelvic MRI compared with conventional T2 TSE in terms of image quality and scan time. METHODS Between May 2021 and September 2021, 52 women (mean age, 44 years ± 12) who underwent 3-T pelvic MRI with additional T2-TSE using a DLR algorithm were included in this single-center prospective study with patient's informed consents. Conventional, DLR, and DLR T2-TSE images with reduced scan times were independently assessed and compared by four radiologists. The overall image quality, differentiation of anatomic details, lesion conspicuity, and artifacts were evaluated using a 5-point scale. Inter-observer agreement of the qualitative scores was compared and reader protocol preferences were then evaluated. RESULTS In the qualitative analysis of all readers, fast DLR T2-TSE showed significantly better overall image quality, differentiation of anatomic regions, lesion conspicuity, and lesser artifacts than conventional T2-TSE and DLR T2-TSE, despite approximately 50% reduction in scan time (all p < 0.05). The inter-reader agreement for the qualitative analysis was moderate to good. All readers preferred DLR over conventional T2-TSE regardless of scan time and preferred fast DLR T2-TSE (57.7-78.8%), except for one who preferred DLR over fast DLR T2-TSE (53.8% vs. 46.1%). CONCLUSION In female pelvic MRI, image quality and accelerated image acquisition for T2-TSE can be significantly improved by using DLR compared to conventional T2-TSE. Fast DLR T2-TSE was non-inferior to DLR T2-TSE in terms of reader preference and image quality. CLINICAL RELEVANCE STATEMENT DLR of T2-TSE in female pelvic MRI enables fast imaging along with maintaining optimal image quality compared with parallel imaging-based conventional T2-TSE. KEY POINTS • Conventional T2 turbo spin-echo based on parallel imaging has limitations for accelerated image acquisition while maintaining good image quality. • Deep learning image reconstruction showed better image quality in both images obtained using the same or accelerated image acquisition parameters compared with conventional T2 turbo spin-echo in female pelvic MRI. • Deep learning image reconstruction enables accelerated image acquisition while maintaining good image quality in the T2-TSE of female pelvic MRI.
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Affiliation(s)
- Eun Ji Lee
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Jiyoung Hwang
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea.
| | - Suyeon Park
- Department of Biostatistics, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea
| | - Sung Hwan Bae
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Jiyun Lim
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Yun-Woo Chang
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Seong Sook Hong
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Eunsun Oh
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Bo Da Nam
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | - Jewon Jeong
- Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesakwan-Ro, Yongsan-Ku, Seoul, 04401, Korea
| | | | - Dominik Nickel
- MR Application Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany
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Multi-Domain Neumann Network with Sensitivity Maps for Parallel MRI Reconstruction. SENSORS 2022; 22:s22103943. [PMID: 35632351 PMCID: PMC9147193 DOI: 10.3390/s22103943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 12/10/2022]
Abstract
MRI is an imaging technology that non-invasively obtains high-quality medical images for diagnosis. However, MRI has the major disadvantage of long scan times which cause patient discomfort and image artifacts. As one of the methods for reducing the long scan time of MRI, the parallel MRI method for reconstructing a high-fidelity MR image from under-sampled multi-coil k-space data is widely used. In this study, we propose a method to reconstruct a high-fidelity MR image from under-sampled multi-coil k-space data using deep-learning. The proposed multi-domain Neumann network with sensitivity maps (MDNNSM) is based on the Neumann network and uses a forward model including coil sensitivity maps for parallel MRI reconstruction. The MDNNSM consists of three main structures: the CNN-based sensitivity reconstruction block estimates coil sensitivity maps from multi-coil under-sampled k-space data; the recursive MR image reconstruction block reconstructs the MR image; and the skip connection accumulates each output and produces the final result. Experiments using the fastMRI T1-weighted brain image dataset were conducted at acceleration factors of 2, 4, and 8. Qualitative and quantitative experimental results show that the proposed MDNNSM method reconstructs MR images more accurately than other methods, including the generalized autocalibrating partially parallel acquisitions (GRAPPA) method and the original Neumann network.
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Liu X, Du H, Xu J, Qiu B. DBGAN: A dual-branch generative adversarial network for undersampled MRI reconstruction. Magn Reson Imaging 2022; 89:77-91. [PMID: 35339616 DOI: 10.1016/j.mri.2022.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/17/2022] [Accepted: 03/19/2022] [Indexed: 11/28/2022]
Abstract
Compressed sensing magnetic resonance imaging (CS-MRI) greatly accelerates the acquisition process and yield considerable reconstructed images. Deep learning was introduced into CS-MRI to further speed up the reconstruction process and improve the image quality. Recently, generative adversarial network (GAN) using two-stage cascaded U-Net structure as generator has been proven to be effective in MRI reconstruction. However, previous cascaded structure was limited to few feature information propagation channels thus may lead to information missing. In this paper, we proposed a GAN-based model, DBGAN, for MRI reconstruction from undersampled k-space data. The model uses cross-stage skip connection (CSSC) between two end-to-end cascaded U-Net in our generator to widen the channels of feature propagation. To avoid discrepancy between training and inference, we replaced classical batch normalization (BN) with instance normalization (IN) . A stage loss is involved in the loss function to boost the training performance. In addition, a bilinear interpolation decoder branch is introduced in the generator to supplement the missing information of the deconvolution decoder. Tested under five variant patterns with four undersampling rates on different modality of MRI data, the quantitative results show that DBGAN model achieves mean improvements of 3.65 dB in peak signal-to-noise ratio (PSNR) and 0.016 in normalized mean square error (NMSE) compared with state-of-the-art GAN-based methods on T1-Weighted brain dataset from MICCAI 2013 grand challenge. The qualitative visual results show that our method can reconstruct considerable images on brain and knee MRI data from different modality. Furthermore, DBGAN is light and fast - the model parameters are fewer than half of state-of-the-art GAN-based methods and each 256 × 256 image is reconstructed in 60 milliseconds, which is suitable for real-time processing.
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Affiliation(s)
- Xianzhe Liu
- Center for Biomedical Image, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hongwei Du
- Center for Biomedical Image, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Jinzhang Xu
- School of Electrical Engineering and Automation, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Bensheng Qiu
- Center for Biomedical Image, University of Science and Technology of China, Hefei, Anhui 230026, China
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Autoencoding Low-Resolution MRI for Semantically Smooth Interpolation of Anisotropic MRI. Med Image Anal 2022; 78:102393. [DOI: 10.1016/j.media.2022.102393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 11/20/2022]
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Wong OL, Poon DM, Kam MK, Lo GG, Fung WW, Man SY, Xue C, Yu SK, Cheung KY, Yuan J. 3D‐T2W‐TSE radiotherapy treatment planning MRI using compressed sensing acceleration for prostate cancer: Image quality and delineation value. Asia Pac J Clin Oncol 2022; 18:e369-e377. [DOI: 10.1111/ajco.13752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 12/13/2021] [Indexed: 11/29/2022]
Affiliation(s)
- Oi Lei Wong
- Research Department Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Darren M.C. Poon
- Comprehensive Oncology Centre Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Miachael K.M. Kam
- Comprehensive Oncology Centre Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Gladys G. Lo
- Department of Diagnostic and Interventional Radiology Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Winky W.K. Fung
- Department of Radiotherapy Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Shei Yee Man
- Department of Radiotherapy Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Cindy Xue
- Research Department Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Siu Ki Yu
- Medical Physics Department Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Kin Yin Cheung
- Medical Physics Department Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
| | - Jing Yuan
- Research Department Hong Kong Sanatorium and Hospital Hong Kong Hong Kong SAR
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Peters S, Gärtner F, Austein F, Wodarg F, Jansen O, Hensler J. Evaluation of an Ultra-Short MRI Protocol for Cerebral Staging Examinations in Melanoma Patients. ROFO-FORTSCHR RONTG 2021; 194:409-415. [PMID: 34794187 DOI: 10.1055/a-1669-9408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE Due to its high sensitivity and lack of radiation, MRI is often used to stage cerebral tumors in patients. In contrast, the relatively long examination times and the limited availability of MRI slots at the clinic might delay these examinations. The aim of this study was to compare an ultra-short MRI protocol with the routinely used standard protocol. MATERIALS AND METHODS Cerebral MRI of 147 patients with malignant melanoma were evaluated retrospectively, whereby only two sequences (FLAIR images and contrast-enhanced T1 MPR images) were evaluated in one group and images from the whole examination were available for the second group, including five sequences (DWI, T2 TSE, FLAIR, native and contrast-enhanced T1 TSE, and contrast-enhanced T1 MPR). The results of the two groups were compared and tested to determine whether the ultra-short approach was inferior to the full examination. RESULTS 13.6 % of the patients had cerebral metastases. Overall, 73 metastases were detected: 60 were located supratentorially and 13 infratentorially. Concerning the detection of cerebral metastases, the ultra-short MRI examination, involving only a FLAIR and a contrast-enhanced T1 MPR sequence, was not inferior to the full MRI protocol in general (p = 0.017) and separated by location for supratentorial (p = 0.026) and infratentorial (p = 0.001) metastases. CONCLUSION For staging purposes, a focused, ultra-short MRI protocol is not inferior to a standard MRI examination. This might open up opportunities for faster staging processes and a more efficient use of the often-restricted MRI capacities. KEY POINTS · Short MRI protocols for cerebral staging are not inferior to standard examinations.. · Contrast-enhanced images represent the centerpiece of an ultra-short MRI protocol.. · Short MRI protocols might enable a more efficient use of restricted resources.. CITATION FORMAT · Peters S, Gärtner F, Austein F et al. Evaluation of an Ultra-Short MRI Protocol for Cerebral Staging Examinations in Melanoma Patients. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1669-9408.
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Affiliation(s)
- Sönke Peters
- Department of Radiology and Neuroradiology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Germany
| | - Friederike Gärtner
- Department of Radiology and Neuroradiology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Germany
| | - Friederike Austein
- Department of Diagnostic and Interventional Neuroradiology, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Fritz Wodarg
- Department of Radiology and Neuroradiology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Germany
| | - Olav Jansen
- Department of Radiology and Neuroradiology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Germany
| | - Johannes Hensler
- Department of Radiology and Neuroradiology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Germany
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Wave-controlled aliasing in parallel imaging magnetization-prepared gradient echo (wave-CAIPI MPRAGE) accelerates speed for pediatric brain MRI with comparable diagnostic performance. Sci Rep 2021; 11:13296. [PMID: 34168260 PMCID: PMC8225910 DOI: 10.1038/s41598-021-92759-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 06/11/2021] [Indexed: 01/07/2023] Open
Abstract
We aimed to compare accelerated post-contrast magnetization-prepared rapid gradient-echo (MPRAGE) using wave-controlled aliasing in parallel imaging (wave-CAIPI) with conventional MPRAGE as a reliable method to diagnose intracranial lesions in pediatric patients. A total of 23 consecutive pediatric patients who underwent post-contrast wave-CAIPI and conventional MPRAGE (scan time: 2 min 39 s vs. 5 min 46 s) were retrospectively evaluated. Two radiologists independently assessed each image for the presence of intracranial lesions. Quantitative [contrast-to-noise ratio (CNR), contrast rate (CR), and signal-to-noise ratio (SNR)] and qualitative parameters (overall image quality, gray-white matter differentiation, demarcation of basal ganglia and sulci, and motion artifacts) were also surveyed. Wave-CAIPI MPRAGE and conventional MPRAGE detected enhancing and non-enhancing intracranial lesions with 100% agreement. Although wave-CAIPI MPRAGE had a lower SNR (all p < 0.05) and overall image quality (overall analysis, p = 0.02) compared to conventional MPRAGE, other quantitative (CNR and CR) and qualitative parameters (gray-white differentiation, demarcation of basal ganglia and sulci, and motion artifacts) were comparable in the pooled analysis and between both observers (all p > 0.05). Wave-CAIPI MPRAGE was a reliable method for diagnosing intracranial lesions in pediatric patients as conventional MPRAGE at half the scan time.
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Shin Y, Yang J, Lee YH. Deep Generative Adversarial Networks: Applications in Musculoskeletal Imaging. Radiol Artif Intell 2021; 3:e200157. [PMID: 34136816 PMCID: PMC8204145 DOI: 10.1148/ryai.2021200157] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 02/10/2021] [Accepted: 02/16/2021] [Indexed: 12/12/2022]
Abstract
In recent years, deep learning techniques have been applied in musculoskeletal radiology to increase the diagnostic potential of acquired images. Generative adversarial networks (GANs), which are deep neural networks that can generate or transform images, have the potential to aid in faster imaging by generating images with a high level of realism across multiple contrast and modalities from existing imaging protocols. This review introduces the key architectures of GANs as well as their technical background and challenges. Key research trends are highlighted, including: (a) reconstruction of high-resolution MRI; (b) image synthesis with different modalities and contrasts; (c) image enhancement that efficiently preserves high-frequency information suitable for human interpretation; (d) pixel-level segmentation with annotation sharing between domains; and (e) applications to different musculoskeletal anatomies. In addition, an overview is provided of the key issues wherein clinical applicability is challenging to capture with conventional performance metrics and expert evaluation. When clinically validated, GANs have the potential to improve musculoskeletal imaging. Keywords: Adults and Pediatrics, Computer Aided Diagnosis (CAD), Computer Applications-General (Informatics), Informatics, Skeletal-Appendicular, Skeletal-Axial, Soft Tissues/Skin © RSNA, 2021.
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Affiliation(s)
- YiRang Shin
- From the Department of Radiology, Research Institute of Radiological Science, and Center for Clinical Imaging Data Science (CCIDS), Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 220-701, Republic of Korea (Y.S., J.Y., Y.H.L.); Systems Molecular Radiology at Yonsei (SysMolRaY), Seoul, Republic of Korea (J.Y.); and Severance Biomedical Science Institute (SBSI), Yonsei University College of Medicine, Seoul, Republic of Korea (J.Y.)
| | - Jaemoon Yang
- From the Department of Radiology, Research Institute of Radiological Science, and Center for Clinical Imaging Data Science (CCIDS), Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 220-701, Republic of Korea (Y.S., J.Y., Y.H.L.); Systems Molecular Radiology at Yonsei (SysMolRaY), Seoul, Republic of Korea (J.Y.); and Severance Biomedical Science Institute (SBSI), Yonsei University College of Medicine, Seoul, Republic of Korea (J.Y.)
| | - Young Han Lee
- From the Department of Radiology, Research Institute of Radiological Science, and Center for Clinical Imaging Data Science (CCIDS), Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 220-701, Republic of Korea (Y.S., J.Y., Y.H.L.); Systems Molecular Radiology at Yonsei (SysMolRaY), Seoul, Republic of Korea (J.Y.); and Severance Biomedical Science Institute (SBSI), Yonsei University College of Medicine, Seoul, Republic of Korea (J.Y.)
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Joseph D, Sukumaran S, Chandra K, Pudakalakatti SM, Dubey A, Singh A, Atreya HS. Rapid nuclear magnetic resonance data acquisition with improved resolution and sensitivity for high-throughput metabolomic analysis. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:300-314. [PMID: 33030750 DOI: 10.1002/mrc.5106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/18/2020] [Accepted: 10/04/2020] [Indexed: 06/11/2023]
Abstract
Nuclear magnetic resonance (NMR)-based metabolomics has witnessed rapid advancements in recent years with the continuous development of new methods to enhance the sensitivity, resolution, and speed of data acquisition. Some of the approaches were earlier used for peptide and protein resonance assignments and have now been adapted to metabolomics. At the same time, new NMR methods involving novel data acquisition techniques, suited particularly for high-throughput analysis in metabolomics, have been developed. In this review, we focus on the different sampling strategies or data acquisition methods that have been developed in our laboratory and other groups to acquire NMR spectra rapidly with high sensitivity and resolution for metabolomics. In particular, we focus on the use of multiple receivers, phase modulation NMR spectroscopy, and fast-pulsing methods for identification and assignments of metabolites.
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Affiliation(s)
- David Joseph
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Sujeesh Sukumaran
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Kousik Chandra
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | | | - Abhinav Dubey
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Amrinder Singh
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Hanudatta S Atreya
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
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Ueda T, Ohno Y, Yamamoto K, Iwase A, Fukuba T, Hanamatsu S, Obama Y, Ikeda H, Ikedo M, Yui M, Murayama K, Toyama H. Compressed sensing and deep learning reconstruction for women's pelvic MRI denoising: Utility for improving image quality and examination time in routine clinical practice. Eur J Radiol 2020; 134:109430. [PMID: 33276249 DOI: 10.1016/j.ejrad.2020.109430] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/03/2020] [Accepted: 11/16/2020] [Indexed: 12/14/2022]
Abstract
PURPOSE To demonstrate the utility of compressed sensing with parallel imaging (Compressed SPEEDER) and AiCE compared with that of conventional parallel imaging (SPEEDER) for shortening examination time and improving image quality of women's pelvic MRI. METHOD Thirty consecutive patients with women's pelvic diseases (mean age 50 years) underwent T2-weighted imaging using Compressed SPEEDER as well as conventional SPEEDER reconstructed with and without AiCE. The examination times were recorded, and signal-to-noise ratio (SNR) was calculated for every patient. Moreover, overall image quality was assessed using a 5-point scoring system, and final scores for all patients were determined by consensus of two readers. Mean examination time, SNR and overall image quality were compared among the four data sets by Wilcoxon signed-rank test. RESULTS Examination times for Compressed SPEEDER with and without AiCE were significantly shorter than those for conventional SPEEDER with and without AiCE (with AiCE: p < 0.0001, without AiCE: p < 0.0001). SNR of Compressed SPEEDER and of SPEEDER with AiCE was significantly superior to that of Compressed SPEEDER without AiCE (vs. Compressed SPEEDER, p = 0.01; vs. SPEEDER, p = 0.009). Overall image quality of Compressed SPEEDER with AiCE and of SPEEDER with and without AiCE was significantly higher than that of Compressed SPEEDER without AiCE (vs. Compressed SPEEDER with AiCE, p < 0.0001; vs. SPEEDER with AiCE, p < 0.0001; SPEEDER without AiCE, p = 0.0003). CONCLUSION Image quality and shorten examination time for T2-weighted imaging in women's pelvic MRI can be significantly improved by using Compressed SPEEDER with AiCE in comparison with conventional SPEEDER, although other sequences were not tested.
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Affiliation(s)
- Takahiro Ueda
- Department of Radiology, Fujita Health University, School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Yoshiharu Ohno
- Department of Radiology, Fujita Health University, School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan; Joint Research Laboratory of Advanced Medical Imaging, Fujita Health University School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Kaori Yamamoto
- Canon Medical Systems Corporation, 1385, Shimoishigami, Otawara, Tochigi, 324-0036, Japan.
| | - Akiyoshi Iwase
- Department of Radiology, Fujita Health University Hospital, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Takashi Fukuba
- Department of Radiology, Fujita Health University Hospital, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Satomu Hanamatsu
- Department of Radiology, Fujita Health University, School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Yuki Obama
- Department of Radiology, Fujita Health University, School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Hirotaka Ikeda
- Department of Radiology, Fujita Health University, School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Masato Ikedo
- Canon Medical Systems Corporation, 1385, Shimoishigami, Otawara, Tochigi, 324-0036, Japan.
| | - Masao Yui
- Canon Medical Systems Corporation, 1385, Shimoishigami, Otawara, Tochigi, 324-0036, Japan.
| | - Kazuhiro Murayama
- Joint Research Laboratory of Advanced Medical Imaging, Fujita Health University School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Hiroshi Toyama
- Department of Radiology, Fujita Health University, School of Medicine, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
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12
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Chaudhari AS, Stevens KJ, Wood JP, Chakraborty AK, Gibbons EK, Fang Z, Desai AD, Lee JH, Gold GE, Hargreaves BA. Utility of deep learning super-resolution in the context of osteoarthritis MRI biomarkers. J Magn Reson Imaging 2020; 51:768-779. [PMID: 31313397 PMCID: PMC6962563 DOI: 10.1002/jmri.26872] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Super-resolution is an emerging method for enhancing MRI resolution; however, its impact on image quality is still unknown. PURPOSE To evaluate MRI super-resolution using quantitative and qualitative metrics of cartilage morphometry, osteophyte detection, and global image blurring. STUDY TYPE Retrospective. POPULATION In all, 176 MRI studies of subjects at varying stages of osteoarthritis. FIELD STRENGTH/SEQUENCE Original-resolution 3D double-echo steady-state (DESS) and DESS with 3× thicker slices retrospectively enhanced using super-resolution and tricubic interpolation (TCI) at 3T. ASSESSMENT A quantitative comparison of femoral cartilage morphometry was performed for the original-resolution DESS, the super-resolution, and the TCI scans in 17 subjects. A reader study by three musculoskeletal radiologists assessed cartilage image quality, overall image sharpness, and osteophytes incidence in all three sets of scans. A referenceless blurring metric evaluated blurring in all three image dimensions for the three sets of scans. STATISTICAL TESTS Mann-Whitney U-tests compared Dice coefficients (DC) of segmentation accuracy for the DESS, super-resolution, and TCI images, along with the image quality readings and blurring metrics. Sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence intervals compared osteophyte detection for the super-resolution and TCI images, with the original-resolution as a reference. RESULTS DC for the original-resolution (90.2 ± 1.7%) and super-resolution (89.6 ± 2.0%) were significantly higher (P < 0.001) than TCI (86.3 ± 5.6%). Segmentation overlap of super-resolution with the original-resolution (DC = 97.6 ± 0.7%) was significantly higher (P < 0.0001) than TCI overlap (DC = 95.0 ± 1.1%). Cartilage image quality for sharpness and contrast levels, and the through-plane quantitative blur factor for super-resolution images, was significantly (P < 0.001) better than TCI. Super-resolution osteophyte detection sensitivity of 80% (76-82%), specificity of 93% (92-94%), and DOR of 32 (22-46) was significantly higher (P < 0.001) than TCI sensitivity of 73% (69-76%), specificity of 90% (89-91%), and DOR of 17 (13-22). DATA CONCLUSION Super-resolution appears to consistently outperform naïve interpolation and may improve image quality without biasing quantitative biomarkers. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:768-779.
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Affiliation(s)
| | - Kathryn J Stevens
- Department of Radiology, Stanford University, Stanford, California, USA
- Department of Orthopaedic Surgery, Stanford University, Stanford, California, USA
| | - Jeff P Wood
- Austin Radiological Association, Austin, Texas, USA
| | | | - Eric K Gibbons
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, USA
| | | | - Arjun D Desai
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Jin Hyung Lee
- Department of Neurology & Neurological Sciences, Stanford University, Stanford, California, USA
- Department of Bioengineering, Stanford University, Stanford, California, USA
- Department of Neurosurgery, Stanford University, Stanford, California, USA
| | - Garry E Gold
- Department of Radiology, Stanford University, Stanford, California, USA
- Department of Orthopaedic Surgery, Stanford University, Stanford, California, USA
- Department of Bioengineering, Stanford University, Stanford, California, USA
| | - Brian A Hargreaves
- Department of Radiology, Stanford University, Stanford, California, USA
- Department of Bioengineering, Stanford University, Stanford, California, USA
- Department of Electrical Engineering, Stanford University, Stanford, California, USA
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13
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Ryu KH, Baek HJ, Skare S, Moon JI, Choi BH, Park SE, Ha JY, Kim TB, Hwang MJ, Sprenger T. Clinical Experience of 1-Minute Brain MRI Using a Multicontrast EPI Sequence in a Different Scan Environment. AJNR Am J Neuroradiol 2020; 41:424-429. [PMID: 32029473 DOI: 10.3174/ajnr.a6427] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 01/02/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND PURPOSE The long scan time of MR imaging is a major drawback limiting its clinical use in neuroimaging; therefore, we aimed to investigate the clinical feasibility of a 1-minute full-brain MR imaging using a multicontrast EPI sequence on a different MR imaging scanner than the ones previously reported. MATERIALS AND METHODS We retrospectively reviewed the records of 146 patients who underwent a multicontrast EPI sequence, including T1-FLAIR, T2-FLAIR, T2WI, DWI, and T2*WI sequences. Two attending neuroradiologists assessed the image quality of each sequence to compare the multicontrast EPI sequence with routine MR imaging protocols. We used the Wilcoxon signed rank test and McNemar test to compare the 2 MR imaging protocols. RESULTS The multicontrast EPI sequence generally showed sufficient image quality of >2 points using a 4-point assessment scale. Regarding image quality and susceptibility artifacts, there was no significant difference between the multicontrast EPI sequence DWI and routine DWI (P > .05), attesting to noninferiority of the multicontrast EPI, whereas there were significant differences in the other 4 sequences between the 2 MR imaging protocols. CONCLUSIONS The multicontrast EPI sequence showed sufficient image quality for clinical use with a shorter scan time; however, it was limited by inferior image quality and frequent susceptibility artifacts compared with routine brain MR imaging. Therefore, the multicontrast EPI sequence cannot completely replace the routine MR imaging protocol at present; however, it may be a feasible option in specific clinical situations such as screening, time-critical diseases or for use with patients prone to motion.
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Affiliation(s)
- K H Ryu
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - H J Baek
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea .,Department of Radiology (H.J.B.), Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Republic of Korea
| | - S Skare
- Department of Clinical Neuroscience (S.S., T.S.), Karolinska Institute, Stockholm, Sweden.,Department of Neuroradiology (S.S.), Karolinska University Hospital, Stockholm, Sweden
| | - J I Moon
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - B H Choi
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - S E Park
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - J Y Ha
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - T B Kim
- From the Department of Radiology (K.H.R., H.J.B., J.I.M., B.H.C., S.E.P., J.Y.H., T.B.K.), Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - M J Hwang
- MR Applications and Workflow, GE Healthcare (M.J.H.), Seoul, Republic of Korea
| | - T Sprenger
- Department of Clinical Neuroscience (S.S., T.S.), Karolinska Institute, Stockholm, Sweden.,MR Applied Science Laboratory Europe (T.S.), GE Healthcare Stockholm, Sweden
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14
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Zhang Q, Ruan G, Yang W, Liu Y, Zhao K, Feng Q, Chen W, Wu EX, Feng Y. MRI Gibbs‐ringing artifact reduction by means of machine learning using convolutional neural networks. Magn Reson Med 2019; 82:2133-2145. [DOI: 10.1002/mrm.27894] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 06/11/2019] [Accepted: 06/14/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Qianqian Zhang
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
| | - Guohui Ruan
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
| | - Wei Yang
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
| | - Yilong Liu
- Laboratory of Biomedical Imaging and Signal Processing The University of Hong Kong Hong Kong SAR China
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong SAR China
| | - Kaixuan Zhao
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
| | - Qianjin Feng
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
| | - Wufan Chen
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
| | - Ed X. Wu
- Laboratory of Biomedical Imaging and Signal Processing The University of Hong Kong Hong Kong SAR China
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong SAR China
| | - Yanqiu Feng
- School of Biomedical Engineering Southern Medical University Guangzhou China
- Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangzhou China
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15
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Novel Technique of Coregistered Intraoperative Computed Tomography and Preoperative Magnetic Resonance Imaging and Diffusion Tensor Imaging Navigation in Spinal Cord Tumor Resection. Ochsner J 2019; 19:43-48. [PMID: 30983901 DOI: 10.31486/toj.18.0107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Background: Intradural spinal tumors are surgically challenging lesions, and intraoperative spinal navigation offers clear potential assistance. While intraoperative computed tomography (iCT) of bony anatomy is routinely performed, coregistration with magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to facilitate intradural spinal tumor resection is not widely described. We present 2 cases in which iCT was coregistered with MRI and DTI for navigational guidance in the resection of intradural spinal tumors to assess technical feasibility and surgical efficacy. Case Series: Navigation using coregistered iCT/MRI was used in the resection of one extramedullary and one intramedullary cervicomedullary tumor. The iCT was obtained following open midline exposure of bony anatomy. The images were then coregistered with preoperative MRI sequences to allow for optical tracking navigation via an optical tracking station (Brainlab). For the intramedullary tumor, preoperative DTI sequences were also coregistered for enhanced identification of relevant anatomy. Navigational accuracy for all cases was confirmed to be acceptable at the level of the posterior bony elements, the dura, and the tumor-parenchyma interface. Conclusion: The coregistration of preoperative MRI sequences and iCT images allowed for meaningfully enhanced navigation during resection. In the case involving the intramedullary cervicomedullary tumor with marked distortion of longitudinal tracts, iCT/DTI navigation allowed for accurate visualization of critical structures and facilitated delineation of tumor margins that otherwise would have been difficult. The use of combined iCT and preoperative MRI/DTI neuronavigational guidance is an effective approach in the resection of intradural extramedullary and intramedullary spinal cord tumors.
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16
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Ryu KH, Choi DS, Baek HJ, Cho SB, Ha JY, Kim TB, Hwang MJ. Clinical feasibility of 1-min ultrafast brain MRI compared with routine brain MRI using synthetic MRI: a single center pilot study. J Neurol 2018; 266:431-439. [DOI: 10.1007/s00415-018-9149-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/03/2018] [Accepted: 12/04/2018] [Indexed: 12/24/2022]
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17
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Paganelli C, Whelan B, Peroni M, Summers P, Fast M, van de Lindt T, McClelland J, Eiben B, Keall P, Lomax T, Riboldi M, Baroni G. MRI-guidance for motion management in external beam radiotherapy: current status and future challenges. Phys Med Biol 2018; 63:22TR03. [PMID: 30457121 DOI: 10.1088/1361-6560/aaebcf] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
High precision conformal radiotherapy requires sophisticated imaging techniques to aid in target localisation for planning and treatment, particularly when organ motion due to respiration is involved. X-ray based imaging is a well-established standard for radiotherapy treatments. Over the last few years, the ability of magnetic resonance imaging (MRI) to provide radiation-free images with high-resolution and superb soft tissue contrast has highlighted the potential of this imaging modality for radiotherapy treatment planning and motion management. In addition, these advantageous properties motivated several recent developments towards combined MRI radiation therapy treatment units, enabling in-room MRI-guidance and treatment adaptation. The aim of this review is to provide an overview of the state-of-the-art in MRI-based image guidance for organ motion management in external beam radiotherapy. Methodological aspects of MRI for organ motion management are reviewed and their application in treatment planning, in-room guidance and adaptive radiotherapy described. Finally, a roadmap for an optimal use of MRI-guidance is highlighted and future challenges are discussed.
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Affiliation(s)
- C Paganelli
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy. Author to whom any correspondence should be addressed. www.cartcas.polimi.it
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18
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Quan TM, Nguyen-Duc T, Jeong WK. Compressed Sensing MRI Reconstruction Using a Generative Adversarial Network With a Cyclic Loss. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:1488-1497. [PMID: 29870376 DOI: 10.1109/tmi.2018.2820120] [Citation(s) in RCA: 241] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Compressed sensing magnetic resonance imaging (CS-MRI) has provided theoretical foundations upon which the time-consuming MRI acquisition process can be accelerated. However, it primarily relies on iterative numerical solvers, which still hinders their adaptation in time-critical applications. In addition, recent advances in deep neural networks have shown their potential in computer vision and image processing, but their adaptation to MRI reconstruction is still in an early stage. In this paper, we propose a novel deep learning-based generative adversarial model, RefineGAN, for fast and accurate CS-MRI reconstruction. The proposed model is a variant of fully-residual convolutional autoencoder and generative adversarial networks (GANs), specifically designed for CS-MRI formulation; it employs deeper generator and discriminator networks with cyclic data consistency loss for faithful interpolation in the given under-sampled -space data. In addition, our solution leverages a chained network to further enhance the reconstruction quality. RefineGAN is fast and accurate-the reconstruction process is extremely rapid, as low as tens of milliseconds for reconstruction of a image, because it is one-way deployment on a feed-forward network, and the image quality is superior even for extremely low sampling rate (as low as 10%) due to the data-driven nature of the method. We demonstrate that RefineGAN outperforms the state-of-the-art CS-MRI methods by a large margin in terms of both running time and image quality via evaluation using several open-source MRI databases.
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Schatlo B, Remonda L, Gruber P, Fandino J, Rohde V, Fathi AR, Berberat J. Cervical Spine Prospective Feasibility Study : Dynamic Flexion-Extension Diffusion-Tensor Weighted Magnetic Resonance Imaging. Clin Neuroradiol 2018; 29:523-532. [PMID: 29671001 DOI: 10.1007/s00062-018-0686-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/30/2018] [Indexed: 11/24/2022]
Abstract
PURPOSE Diffusion tensor imaging (DTI) in flexion-extension may serve as a diagnostic tool to improve the sensitivity for detection of myelopathy. In this study, the feasibility and reproducibility of dynamic DTI in the cervical spinal cord was assessed in healthy volunteers and patients. METHODS All subjects were examined in maximum neck flexion-extension in a 3T magnetic resonance imaging (MRI) scanner. Range of motion, space available for the spinal cord, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured and compared between the neck positions. RESULTS Volunteers showed no variation in ADC and FA. In patients, extension produced higher ADC in the diseased than in the control segments (p = 0.0045). The ADC of the affected segments was higher in extension than in the neutral position (p = 0.0030) or in flexion (p = 0.0002). The FA was significantly lower in extension in patients at both the control level C2/3 (p = 0.0154) and the affected segment (p = 0.0187). CONCLUSIONS Dynamic DTI of the cervical spine is feasible and ADC increased in the patient group in extension. This finding may open a previously unexplored avenue to attempt an earlier identification of myelopathy.
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Affiliation(s)
- Bawarjan Schatlo
- Department of Neuroradiology, Cantonal Hospital Aarau, Tellstraße 25, 5001, Aarau, Switzerland.,Department of Neurosurgery, Cantonal Hospital Aarau, Aarau, Switzerland.,Department of Neurosurgery, University Medicine Göttingen, Georg-August University, Göttingen, Germany
| | - Luca Remonda
- Department of Neuroradiology, Cantonal Hospital Aarau, Tellstraße 25, 5001, Aarau, Switzerland
| | - Philipp Gruber
- Department of Neurology, Cantonal Hospital Aarau, Aarau, Switzerland
| | - Javier Fandino
- Department of Neurosurgery, Cantonal Hospital Aarau, Aarau, Switzerland
| | - Veit Rohde
- Department of Neurosurgery, University Medicine Göttingen, Georg-August University, Göttingen, Germany
| | - Ali-Reza Fathi
- Department of Neurosurgery, Hirslanden Clinik, Aarau, Switzerland
| | - Jatta Berberat
- Department of Neuroradiology, Cantonal Hospital Aarau, Tellstraße 25, 5001, Aarau, Switzerland.
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Kim JJ, Nam J, Jang IG. Computational study of estimating 3D trabecular bone microstructure for the volume of interest from CT scan data. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2950. [PMID: 29218827 DOI: 10.1002/cnm.2950] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/15/2017] [Accepted: 11/25/2017] [Indexed: 06/07/2023]
Abstract
Inspired by the self-optimizing capabilities of bone, a new concept of bone microstructure reconstruction has been recently introduced by using 2D synthetic skeletal images. As a preliminary clinical study, this paper proposes a topology optimization-based method that can estimate 3D trabecular bone microstructure for the volume of interest (VOI) from 3D computed tomography (CT) scan data with enhanced computational efficiency and phenomenological accuracy. For this purpose, a localized finite element (FE) model is constructed by segmenting a target bone from CT scan data and determining the physiological local loads for the VOI. Then, topology optimization is conducted with multiresolution bone mineral density (BMD) deviation constraints to preserve the patient-specific spatial bone distribution obtained from the CT scan data. For the first time, to our knowledge, this study has demonstrated that 60-μm resolution trabecular bone images can be reconstructed from 600-μm resolution CT scan data (a 62-year-old woman with no metabolic bone disorder) for the 4 VOIs in the proximal femur. The reconstructed trabecular bone includes the characteristic trabecular patterns and has morphometric indices that are in good agreement with the anatomical data in the literature. As for computational efficiency, the localization for the VOI reduces the number of FEs by 99%, compared with that of the full FE model. Compared with the previous single-resolution BMD deviation constraint, the proposed multiresolution BMD deviation constraints enable at least 65% and 47% reductions in the number of iterations and computing time, respectively. These results demonstrate the clinical feasibility and potential of the proposed method.
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Affiliation(s)
- Jung Jin Kim
- The Cho Chun Shik Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
| | - Jimin Nam
- The Cho Chun Shik Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
| | - In Gwun Jang
- The Cho Chun Shik Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
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21
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Comparison of a fast 5-min knee MRI protocol with a standard knee MRI protocol: a multi-institutional multi-reader study. Skeletal Radiol 2018; 47:107-116. [PMID: 28952012 DOI: 10.1007/s00256-017-2780-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/30/2017] [Accepted: 09/18/2017] [Indexed: 02/02/2023]
Abstract
PURPOSE To compare diagnostic performance of a 5-min knee MRI protocol to that of a standard knee MRI. MATERIALS AND METHODS One hundred 3 T (100 patients, mean 38.8 years) and 50 1.5 T (46 patients, mean 46.4 years) MRIs, consisting of 5 fast, 2D multi-planar fast-spin-echo (FSE) sequences and five standard multiplanar FSE sequences, from two academic centers (1/2015-1/2016), were retrospectively reviewed by four musculoskeletal radiologists. Agreement between fast and standard (interprotocol agreement) and between standard (intraprotocol agreement) readings for meniscal, ligamentous, chondral, and bone pathology was compared for interchangeability. Frequency of major findings, sensitivity, and specificity was also tested for each protocol. RESULTS Interprotocol agreement using fast MRI was similar to intraprotocol agreement with standard MRI (83.0-99.5%), with no excess disagreement (≤ 1.2; 95% CI, -4.2 to 3.8%), across all structures. Frequency of major findings (1.1-22.4% across structures) on fast and standard MRI was not significantly different (p ≥ 0.215), except more ACL tears on fast MRI (p = 0.021) and more cartilage defects on standard MRI (p < 0.001). Sensitivities (59-100%) and specificities (73-99%) of fast and standard MRI were not significantly different for meniscal and ligament tears (95% CI for difference, -0.08-0.08). For cartilage defects, fast MRI was slightly less sensitive (95% CI for difference, -0.125 to -0.01) but slightly more specific (95% CI for difference, 0.01-0.5) than standard MRI. CONCLUSION A fast 5-min MRI protocol is interchangeable with and has similar accuracy to a standard knee MRI for evaluating internal derangement of the knee.
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Bouhrara M, Spencer RG. Fisher information and Cramér-Rao lower bound for experimental design in parallel imaging. Magn Reson Med 2017; 79:3249-3255. [PMID: 29090485 DOI: 10.1002/mrm.26984] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Revised: 09/14/2017] [Accepted: 10/04/2017] [Indexed: 01/13/2023]
Abstract
PURPOSE The Cramér-Rao lower bound (CRLB) is widely used in the design of magnetic resonance (MR) experiments for parameter estimation. Previous work has considered only Gaussian or Rician noise distributions in this calculation. However, the noise distribution for multi-coil acquisitions, such as in parallel imaging, obeys the noncentral χ-distribution under many circumstances. The purpose of this paper is to present the CRLB calculation for parameter estimation from multi-coil acquisitions. THEORY AND METHODS We perform explicit calculations of Fisher matrix elements and the associated CRLB for noise distributions following the noncentral χ-distribution. The special case of diffusion kurtosis is examined as an important example. For comparison with analytic results, Monte Carlo (MC) simulations were conducted to evaluate experimental minimum standard deviations (SDs) in the estimation of diffusion kurtosis model parameters. Results were obtained for a range of signal-to-noise ratios (SNRs), and for both the conventional case of Gaussian noise distribution and noncentral χ-distribution with different numbers of coils, m. RESULTS At low-to-moderate SNR, the noncentral χ-distribution deviates substantially from the Gaussian distribution. Our results indicate that this departure is more pronounced for larger values of m. As expected, the minimum SDs (i.e., CRLB) in derived diffusion kurtosis model parameters assuming a noncentral χ-distribution provided a closer match to the MC simulations as compared to the Gaussian results. CONCLUSION Estimates of minimum variance for parameter estimation and experimental design provided by the CRLB must account for the noncentral χ-distribution of noise in multi-coil acquisitions, especially in the low-to-moderate SNR regime. Magn Reson Med 79:3249-3255, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Mustapha Bouhrara
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Richard G Spencer
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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Nabavizadeh SA, Chawla S, Agarwal M, Mohan S. Chapter 8 On the Horizon: Advanced Imaging Techniques to Improve Noninvasive Assessment of Cervical Lymph Nodes. Semin Ultrasound CT MR 2017; 38:542-556. [PMID: 29031370 DOI: 10.1053/j.sult.2017.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Conventional imaging modalities are limited in the evaluation of lymph nodes as they predominantly rely on size and morphology, which have suboptimal sensitivity and specificity for malignancy. In this review we will explore the role of "on the horizon" advanced imaging modalities that can look beyond the size and morphologic features of a cervical lymph node and explore its molecular nature and can aid in personalizing therapy rather than use the "one-size-fits-all" approach.
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Affiliation(s)
- Seyed Ali Nabavizadeh
- Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Sanjeev Chawla
- Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Mohit Agarwal
- Division of Neuroradiology, Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
| | - Suyash Mohan
- Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
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Fagundes J, Longo MG, Huang SY, Rosen BR, Witzel T, Heberlein K, Gonzalez RG, Schaefer P, Rapalino O. Diagnostic Performance of a 10-Minute Gadolinium-Enhanced Brain MRI Protocol Compared with the Standard Clinical Protocol for Detection of Intracranial Enhancing Lesions. AJNR Am J Neuroradiol 2017; 38:1689-1694. [PMID: 28705816 DOI: 10.3174/ajnr.a5293] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 05/12/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The development of new MR imaging scanners with stronger gradients and improvement in coil technology, allied with emerging fast imaging techniques, has allowed a substantial reduction in MR imaging scan times. Our goal was to develop a 10-minute gadolinium-enhanced brain MR imaging protocol with accelerated sequences and to evaluate its diagnostic performance compared with the standard clinical protocol. MATERIALS AND METHODS Fifty-three patients referred for brain MR imaging with contrast were scanned with a 3T scanner. Each MR image consisted of 5 basic fast precontrast sequences plus standard and accelerated versions of the same postcontrast T1WI sequences. Two neuroradiologists assessed the image quality and the final diagnosis for each set of postcontrast sequences and compared their performances. RESULTS The acquisition time of the combined accelerated pre- and postcontrast sequences was 10 minutes and 15 seconds; and of the fast postcontrast sequences, 3 minutes and 36 seconds, 46% of the standard sequences. The 10-minute postcontrast axial T1WI had fewer image artifacts (P < .001) and better overall diagnostic quality (P < .001). Although the 10-minute MPRAGE sequence showed a tendency to have more artifacts than the standard sequence (P = .08), the overall diagnostic quality was similar (P = .66). Moreover, there was no statistically significant difference in the diagnostic performance between the protocols. The sensitivity, specificity, and accuracy values for the 10-minute protocol were 100.0%, 88.9%, and 98.1%. CONCLUSIONS The 10-minute brain MR imaging protocol with contrast is comparable in diagnostic performance with the standard protocol in an inpatient motion-prone population, with the additional benefits of reducing acquisition times and image artifacts.
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Affiliation(s)
- J Fagundes
- From the Clínica de Diagnóstico por Imagem (J.F.), Rio de Janeiro, Brazil
| | - M G Longo
- Department of Radiology (M.G.L., S.Y.H., R.G.G., P.S., O.R.), Massachusetts General Hospital, Boston, Massachusetts
| | - S Y Huang
- Department of Radiology (M.G.L., S.Y.H., R.G.G., P.S., O.R.), Massachusetts General Hospital, Boston, Massachusetts
| | - B R Rosen
- Athinoula A. Martinos Center for Biomedical Imaging (B.R.R., T.W.), Charlestown, Massachusetts
| | - T Witzel
- Athinoula A. Martinos Center for Biomedical Imaging (B.R.R., T.W.), Charlestown, Massachusetts
| | - K Heberlein
- Siemens Medical Solutions (K.H.), Malvern, Pennsylvania
| | - R G Gonzalez
- Department of Radiology (M.G.L., S.Y.H., R.G.G., P.S., O.R.), Massachusetts General Hospital, Boston, Massachusetts
| | - P Schaefer
- Department of Radiology (M.G.L., S.Y.H., R.G.G., P.S., O.R.), Massachusetts General Hospital, Boston, Massachusetts
| | - O Rapalino
- Department of Radiology (M.G.L., S.Y.H., R.G.G., P.S., O.R.), Massachusetts General Hospital, Boston, Massachusetts
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Thornton JS. Technical challenges and safety of magnetic resonance imaging with in situ neuromodulation from spine to brain. Eur J Paediatr Neurol 2017; 21:232-241. [PMID: 27430172 DOI: 10.1016/j.ejpn.2016.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/13/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE This review summarises the need for MRI with in situ neuromodulation, the key safety challenges and how they may be mitigated, and surveys the current status of MRI safety for the main categories of neuro-stimulation device, including deep brain stimulation, vagus nerve stimulation, sacral neuromodulation, spinal cord stimulation systems, and cochlear implants. REVIEW SUMMARY When neuro-stimulator systems are introduced into the MRI environment a number of hazards arise with potential for patient harm, in particular the risk of thermal injury due to MRI-induced heating. For many devices however, safe MRI conditions can be determined, and MRI safely performed, albeit with possible compromise in anatomical coverage, image quality or extended acquisition time. CONCLUSIONS The increasing availability of devices conditional for 3 T MRI, whole-body transmit imaging, and imaging in the on-stimulation condition, will be of significant benefit to the growing population of patients benefitting from neuromodulation therapy, and open up new opportunities for functional imaging research.
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Affiliation(s)
- John S Thornton
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, Queen Square, London, UK; Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College London, London, UK.
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Prakkamakul S, Witzel T, Huang S, Boulter D, Borja MJ, Schaefer P, Rosen B, Heberlein K, Ratai E, Gonzalez G, Rapalino O. Ultrafast Brain MRI: Clinical Deployment and Comparison to Conventional Brain MRI at 3T. J Neuroimaging 2016; 26:503-10. [DOI: 10.1111/jon.12365] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 11/28/2022] Open
Affiliation(s)
- Supada Prakkamakul
- Neuroradiology Division; Department of Radiology; Massachusetts General Hospital; Boston MA
- Department of Radiology; King Chulalongkorn Memorial Hospital; Thai Red Cross Society; Bangkok Thailand
| | - Thomas Witzel
- Department of Radiology; Athinoula A. Martinos Center for Biomedical Imaging; Harvard Medical School; Massachusetts General Hospital; Charlestown MA
| | - Susie Huang
- Neuroradiology Division; Department of Radiology; Massachusetts General Hospital; Boston MA
- Department of Radiology; Athinoula A. Martinos Center for Biomedical Imaging; Harvard Medical School; Massachusetts General Hospital; Charlestown MA
| | - Daniel Boulter
- Neuroradiology Division; Department of Radiology; Ohio State University; Columbus OH
| | - Maria J. Borja
- Neuroradiology Division; Department of Radiology; New York University School of Medicine; New York NY
| | - Pamela Schaefer
- Neuroradiology Division; Department of Radiology; Massachusetts General Hospital; Boston MA
| | - Bruce Rosen
- Department of Radiology; Athinoula A. Martinos Center for Biomedical Imaging; Harvard Medical School; Massachusetts General Hospital; Charlestown MA
| | | | - Eva Ratai
- Neuroradiology Division; Department of Radiology; Massachusetts General Hospital; Boston MA
- Department of Radiology; Athinoula A. Martinos Center for Biomedical Imaging; Harvard Medical School; Massachusetts General Hospital; Charlestown MA
| | - Gilberto Gonzalez
- Neuroradiology Division; Department of Radiology; Massachusetts General Hospital; Boston MA
- Department of Radiology; Athinoula A. Martinos Center for Biomedical Imaging; Harvard Medical School; Massachusetts General Hospital; Charlestown MA
| | - Otto Rapalino
- Neuroradiology Division; Department of Radiology; Massachusetts General Hospital; Boston MA
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Bashar SK, Lee SY, Hasan MK. Empirical mode decomposition based GRAPPA reconstruction algorithm for parallel MRI. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/4/045006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Saeed M, Van TA, Krug R, Hetts SW, Wilson MW. Cardiac MR imaging: current status and future direction. Cardiovasc Diagn Ther 2015; 5:290-310. [PMID: 26331113 DOI: 10.3978/j.issn.2223-3652.2015.06.07] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 06/17/2015] [Indexed: 12/12/2022]
Abstract
Coronary artery disease is currently a worldwide epidemic with increasing impact on healthcare systems. Magnetic resonance imaging (MRI) sequences give complementary information on LV function, regional perfusion, angiogenesis, myocardial viability and orientations of myocytes. T2-weighted short-tau inversion recovery (T2-STIR), fat suppression and black blood sequences have been frequently used for detecting edematous area at risk (AAR) of infarction. T2 mapping, however, indicated that the edematous reaction in acute myocardial infarct (AMI) is not stable and warranted the use of edematous area in evaluating therapies. On the other hand, cine MRI demonstrated reproducible data on LV function in healthy volunteers and LV remodeling in patients. Noninvasive first pass perfusion, using exogenous tracer (gadolinium-based contrast media) and arterial spin labeling MRI, using endogenous tracer (water), are sensitive and useful techniques for evaluating myocardial perfusion and angiogenesis. Recently, new strategies have been developed to quantify myocardial viability using T1-mapping and equilibrium contrast enhanced MR techniques because existing delayed contrast enhancement MRI (DE-MRI) sequences are limited in detecting patchy microinfarct and diffuse fibrosis. These new techniques were successfully used for characterizing diffuse myocardial fibrosis associated with myocarditis, amyloidosis, sarcoidosis heart failure, aortic hypertrophic cardiomyopathy, congenital heart disease, restrictive cardiomyopathy, arrhythmogenic right ventricular dysplasia and hypertension). Diffusion MRI provides information regarding microscopic tissue structure, while diffusion tensor imaging (DTI) helps to characterize the myocardium and monitor the process of LV remodeling after AMI. Novel trends in hybrid imaging, such as cardiac positron emission tomography (PET)/MRI and optical imaging/MRI, are recently under intensive investigation. With the promise of higher spatial-temporal resolution and 3D coverage in the near future, cardiac MRI will be an indispensible tool in the diagnosis of cardiac diseases, coronary intervention and myocardial therapeutic delivery.
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Affiliation(s)
- Maythem Saeed
- 1 Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, San Francisco, CA, USA ; 2 Zentralinstitut für Medizintechnik, Technical University of Munich, Munich, Germany
| | - Tu Anh Van
- 1 Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, San Francisco, CA, USA ; 2 Zentralinstitut für Medizintechnik, Technical University of Munich, Munich, Germany
| | - Roland Krug
- 1 Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, San Francisco, CA, USA ; 2 Zentralinstitut für Medizintechnik, Technical University of Munich, Munich, Germany
| | - Steven W Hetts
- 1 Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, San Francisco, CA, USA ; 2 Zentralinstitut für Medizintechnik, Technical University of Munich, Munich, Germany
| | - Mark W Wilson
- 1 Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, San Francisco, CA, USA ; 2 Zentralinstitut für Medizintechnik, Technical University of Munich, Munich, Germany
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Myocardial blood flow quantification for evaluation of coronary artery disease by positron emission tomography, cardiac magnetic resonance imaging, and computed tomography. Curr Cardiol Rep 2014; 16:483. [PMID: 24718671 DOI: 10.1007/s11886-014-0483-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The noninvasive detection of the presence and functional significance of coronary artery stenosis is important in the diagnosis, risk assessment, and management of patients with known or suspected coronary artery disease. Quantitative assessment of myocardial perfusion can provide an objective and reproducible estimate of myocardial ischemia and risk prediction. Positron emission tomography, cardiac magnetic resonance, and cardiac computed tomography perfusion are modalities capable of measuring myocardial blood flow and coronary flow reserve. In this review, we will discuss the technical aspects of quantitative myocardial perfusion imaging with positron emission tomography, cardiac magnetic resonance imaging, and computed tomography, and its emerging clinical applications.
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30
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Guglielmo FF, Mitchell DG, Roth CG, Deshmukh S. Hepatic MR Imaging Techniques, Optimization, and Artifacts. Magn Reson Imaging Clin N Am 2014; 22:263-82. [DOI: 10.1016/j.mric.2014.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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31
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Hansen MS, Kellman P. Image reconstruction: an overview for clinicians. J Magn Reson Imaging 2014; 41:573-85. [PMID: 24962650 DOI: 10.1002/jmri.24687] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 05/27/2014] [Accepted: 05/27/2014] [Indexed: 12/18/2022] Open
Abstract
Image reconstruction plays a critical role in the clinical use of magnetic resonance imaging (MRI). The MRI raw data is not acquired in image space and the role of the image reconstruction process is to transform the acquired raw data into images that can be interpreted clinically. This process involves multiple signal processing steps that each have an impact on the image quality. This review explains the basic terminology used for describing and quantifying image quality in terms of signal-to-noise ratio and point spread function. In this context, several commonly used image reconstruction components are discussed. The image reconstruction components covered include noise prewhitening for phased array data acquisition, interpolation needed to reconstruct square pixels, raw data filtering for reducing Gibbs ringing artifacts, Fourier transforms connecting the raw data with image space, and phased array coil combination. The treatment of phased array coils includes a general explanation of parallel imaging as a coil combination technique. The review is aimed at readers with no signal processing experience and should enable them to understand what role basic image reconstruction steps play in the formation of clinical images and how the resulting image quality is described.
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Affiliation(s)
- Michael S Hansen
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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Abstract
Proper assessment of the physiologic impact of coronary artery stenosis on the LV myocardium can affect patient prognosis and treatment decisions. Cardiac magnetic resonance imaging (CMR) assesses myocardial perfusion by imaging the myocardium during a first-pass transit of an intravenous gadolinium bolus, with spatial and temporal resolution substantially higher than nuclear myocardial perfusion imaging. Coupled with late gadolinium enhancement (LGE) imaging for infarction during the same imaging session, CMR with vasodilating stress perfusion imaging can qualitatively and quantitatively assess the myocardial extent of hypoperfusion from coronary stenosis independent of infarcted myocardium. This approach has been validated experimentally, and multiple clinical trials have established its diagnostic robustness when compared to stress single-photon emission computed tomography. In specialized centers, dobutamine stress CMR has been shown to have incremental diagnostic value above stress echocardiography due to its high imaging quality and ability to image the heart with no restriction of imaging window. This paper reviews the technical aspects, diagnostic utility, prognostic values, challenges to clinical adaptation, and future developments of stress CMR imaging.
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Stroman PW, Wheeler-Kingshott C, Bacon M, Schwab JM, Bosma R, Brooks J, Cadotte D, Carlstedt T, Ciccarelli O, Cohen-Adad J, Curt A, Evangelou N, Fehlings MG, Filippi M, Kelley BJ, Kollias S, Mackay A, Porro CA, Smith S, Strittmatter SM, Summers P, Tracey I. The current state-of-the-art of spinal cord imaging: methods. Neuroimage 2013; 84:1070-81. [PMID: 23685159 DOI: 10.1016/j.neuroimage.2013.04.124] [Citation(s) in RCA: 228] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 04/08/2013] [Accepted: 04/16/2013] [Indexed: 12/28/2022] Open
Abstract
A first-ever spinal cord imaging meeting was sponsored by the International Spinal Research Trust and the Wings for Life Foundation with the aim of identifying the current state-of-the-art of spinal cord imaging, the current greatest challenges, and greatest needs for future development. This meeting was attended by a small group of invited experts spanning all aspects of spinal cord imaging from basic research to clinical practice. The greatest current challenges for spinal cord imaging were identified as arising from the imaging environment itself; difficult imaging environment created by the bone surrounding the spinal canal, physiological motion of the cord and adjacent tissues, and small cross-sectional dimensions of the spinal cord, exacerbated by metallic implants often present in injured patients. Challenges were also identified as a result of a lack of "critical mass" of researchers taking on the development of spinal cord imaging, affecting both the rate of progress in the field, and the demand for equipment and software to manufacturers to produce the necessary tools. Here we define the current state-of-the-art of spinal cord imaging, discuss the underlying theory and challenges, and present the evidence for the current and potential power of these methods. In two review papers (part I and part II), we propose that the challenges can be overcome with advances in methods, improving availability and effectiveness of methods, and linking existing researchers to create the necessary scientific and clinical network to advance the rate of progress and impact of the research.
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Affiliation(s)
- P W Stroman
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada.
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Bernsen MR, Ruggiero A, van Straten M, Kotek G, Haeck JC, Wielopolski PA, Krestin GP. Computed tomography and magnetic resonance imaging. Recent Results Cancer Res 2013. [PMID: 23179877 DOI: 10.1007/978-3-642-10853-2_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Imaging in Oncology is rapidly moving from the detection and size measurement of a lesion to the quantitative assessment of metabolic processes and cellular and molecular interactions. Increasing insights into cancer as a complex disease with involvement of the tumor stroma in tumor pathobiological processes have made it clear that for successful control of cancer, treatment strategies should not only be directed at the tumor cells but also targeted at the tumor microenvironment. This requires understanding of the complex molecular and cellular interactions in cancer tissue. Recent developments in imaging technology have increased the possibility to image various pathobiological processes in cancer development and response to treatment. For computed tomography (CT) and magnetic resonance imaging (MRI) various improvements in hardware, software, and imaging probes have lifted these modalities from classical anatomical imaging techniques to techniques suitable to image and quantify various physiological processes and molecular and cellular interactions. Next to a more general overview of possible imaging targets in oncology this chapter provides an overview of the various developments in CT and MRI technology and some specific applications.
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Affiliation(s)
- Monique R Bernsen
- Department of Radiology, Erasmus MC-University Medical Center Rotterdam, Rotterdam, The Netherlands.
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Fruehwald-Pallamar J, Szomolanyi P, Fakhrai N, Lunzer A, Weber M, Thurnher MM, Pallamar M, Trattnig S, Prayer D, Noebauer-Huhmann IM. Parallel imaging of the cervical spine at 3T: optimized trade-off between speed and image quality. AJNR Am J Neuroradiol 2012; 33:1867-74. [PMID: 22555578 DOI: 10.3174/ajnr.a3101] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Patients with cervical spine syndrome often experience pain during the MR examination. Our aim was to compare the quality of cervical spine MR images obtained by parallel imaging with those of nonaccelerated images, with the goal of shortening the examination time while preserving adequate image quality. MATERIALS AND METHODS A phantom study and examinations of 10 volunteers and 26 patients were conducted on a clinical 3T scanner. Acquisitions included axial T2WI, sagittal T2WI, T1WI, and T2TIRM sequences. Nonaccelerated sequences and accelerated sequences with different numbers of averages and different accelerations, with a scanning time reduction of 67%, were performed. For quantitative analysis, the SNR was obtained from the phantom measurements, and the NU was calculated from the volunteer measurements. For qualitative analysis, 3 independent readers assessed the delineation of anatomic structures in volunteers and the visibility of degenerative disease in patients. RESULTS In the phantom study, as expected, the SNR of the nonaccelerated images was higher than the SNR of the same sequence with parallel imaging. In vivo, the NU was higher when applying fewer averages or parallel imaging, compared with the nonaccelerated images. The analysis of the subjective parameters in the volunteers and patients showed that a scanning time of 48% of the original protocol could be obtained by combining the following sequences: sagittal T1WI with 1 average; sagittal T2WI with acceleration factor 3; sagittal T2TIRM with acceleration factor 2; and axial T2* GRE with acceleration factor 2. CONCLUSIONS Parallel imaging of the cervical spine at 3T allows shortening of the examination time by 52%, preserving adequate image quality.
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Affiliation(s)
- J Fruehwald-Pallamar
- Subdivision of Neuroradiology and Musculoskeletal Radiology, Department of Radiology, Medical University ofVienna, Waehringer Guertel 18 –20, 1090 Vienna, Austria.
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Weier K, Mazraeh J, Naegelin Y, Thoeni A, Hirsch JG, Fabbro T, Bruni N, Duyar H, Bendfeldt K, Radue EW, Kappos L, Gass A. Biplanar MRI for the assessment of the spinal cord in multiple sclerosis. Mult Scler 2012; 18:1560-9. [DOI: 10.1177/1352458512442754] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective: To investigate the entire spinal cord (SC) of multiple sclerosis (MS) patients with biplanar MRI and to relate these MRI findings to clinical functional scores. Methods: Two hundred and two patients (140 women, 62 men 24–74 years, Expanded Disability Status Scale (EDSS) scores 0–7.5) were investigated clinically and with biplanar MRI. Sagittal and axial proton density weighted (PDw) and T2 weighted (T2w) images of the whole SC were obtained employing parallel imaging. Data were analyzed by consensus reading using a standardized reporting scheme. Different combinations of findings were compared to EDSS scores with Spearman’s rank correlation coefficient (ρ). Results: The combined analysis of sagittal and axial planes demonstrated slightly differing results in 97/202 (48%) patients. There were 9% additional lesions identified, leading to a higher lesion count in 28% of these patients, but also rejection of equivocal abnormality leading to a lower lesion count in 11% of patients. Considering both sagittal and axial images, SC abnormalities were found in 167/202 (83%) patients. When compared with EDSS scores, the combination of focal lesions, signs of atrophy and diffuse abnormalities showed a moderate correlation (ρ=0.52), that precludes its use for individual patient assessment. Conclusion: Biplanar MRI facilitates a comprehensive identification, localization, and grading of pathological SC findings in MS patients. This improves the confidence and utility of SC imaging.
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Affiliation(s)
- Katrin Weier
- Department of Neurology, University Hospital Basel, Switzerland
| | - Jilla Mazraeh
- Division of Neuroradiology, University Hospital Basel, Switzerland
| | - Yvonne Naegelin
- Department of Neurology, University Hospital Basel, Switzerland
| | - Alain Thoeni
- Division of Neuroradiology, University Hospital Basel, Switzerland
- Medical Image Analysis Center, University Hospital Basel, Switzerland
| | - Jochen G Hirsch
- Department of Neurology, University Hospital Basel, Switzerland
- Division of Neuroradiology, University Hospital Basel, Switzerland
| | - Thomas Fabbro
- Study Coordination Center, University Hospital Basel, Switzerland
| | - Nicole Bruni
- Study Coordination Center, University Hospital Basel, Switzerland
| | - Hüseyin Duyar
- Department of Neurology, University Hospital Basel, Switzerland
| | - Kerstin Bendfeldt
- Medical Image Analysis Center, University Hospital Basel, Switzerland
| | - Ernst-Wilhelm Radue
- Division of Neuroradiology, University Hospital Basel, Switzerland
- Medical Image Analysis Center, University Hospital Basel, Switzerland
| | - Ludwig Kappos
- Department of Neurology, University Hospital Basel, Switzerland
| | - Achim Gass
- Department of Neurology, University Hospital Basel, Switzerland
- Division of Neuroradiology, University Hospital Basel, Switzerland
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Utility of pretreatment mean apparent diffusion coefficient and apparent diffusion coefficient histograms in prediction of outcome to chemoradiation in head and neck squamous cell carcinoma. J Comput Assist Tomogr 2012; 36:131-7. [PMID: 22261783 DOI: 10.1097/rct.0b013e3182405435] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE This study aimed to evaluate pretreatment whole-tumor mean apparent diffusion coefficient (ADC) and ADC histogram as predictors of outcome to chemoradiation in patients with head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS Patients with HNSCC underwent pretreatment 3-T diffusion-weighted magnetic resonance imaging with calculation of mean ADC and ADC histograms. Outcomes were determined 2 years after chemoradiation. Positive outcome was defined as no abnormal 18-fluoro deoxy glucose uptake on posttherapy computed tomography-positron emission tomography (or abnormal uptake that was proven benign), no locoregional recurrence or metastatic disease, and no requirement for salvage surgery. Negative outcome was defined as residual abnormal 18-fluoro deoxy glucose avidity that was proven malignant, salvage surgery requirement, locoregional recurrence or metastatic disease, death, or a combination of these. A 2-sample t test was used to compare the mean ADC between patients with positive and negative outcomes. The ADC cut point for dividing the groups was determined by looking at its distribution. A Kaplan-Meier plot was produced, and a log-rank test was conducted with calculation of sensitivity, specificity, and positive and negative predictive values. RESULTS Nine patients showed positive and 8 showed negative outcomes. Significant difference (P = 0.03) was seen in mean ADC (in 10 mm/s) between patients showing positive and negative outcomes (1.18 and 1.43, respectively). According to the log-rank test, tumors with greater than 45% of their volume below the ADC threshold of 1.15 × 10 mm/s were more likely to have a positive outcome (accuracy, 77%). CONCLUSIONS Patients with HNSCC demonstrating lower pretreatment ADC and with greater than 45% of volume below ADC threshold of 1.15 × 10 mm/s may have better outcome to chemoradiation at 2 years.
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Hansch A, Kohlmann P, Hinneburg U, Boettcher J, Malich A, Wolf G, Laue H, Pfeil A. Quantitative evaluation of MR perfusion imaging using blood pool contrast agent in subjects without pulmonary diseases and in patients with pulmonary embolism. Eur Radiol 2012; 22:1748-56. [DOI: 10.1007/s00330-012-2428-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 01/20/2012] [Accepted: 01/27/2012] [Indexed: 11/30/2022]
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O'Donnell DH, Abbara S, Chaithiraphan V, Yared K, Killeen RP, Martos R, Keane D, Cury RC, Dodd JD. Cardiac MR imaging of nonischemic cardiomyopathies: imaging protocols and spectra of appearances. Radiology 2012; 262:403-22. [PMID: 22282181 DOI: 10.1148/radiol.11100284] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent technologic advances in cardiac magnetic resonance (MR) imaging have resulted in images with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MR is a valuable imaging technique for detection and assessment of the morphology and functional characteristics of the nonischemic cardiomyopathy. It has gained acceptance as a standalone imaging modality that can provide further information beyond the capabilities of traditional modalities such as echocardiography and angiography. Black-blood fast spin-echo MR images allow morphologic assessment of the heart with high spatial resolution, while T2-weighted MR images can depict acute myocardial edema. Contrast material-enhanced images can depict and be used to quantify myocardial edema, infiltration, and fibrosis. This review presents recommended cardiac MR protocols for and the spectrum of imaging appearances of the nonischemic cardiomyopathies.
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Affiliation(s)
- David H O'Donnell
- Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA
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Plenge E, Poot DHJ, Bernsen M, Kotek G, Houston G, Wielopolski P, van der Weerd L, Niessen WJ, Meijering E. Super-resolution methods in MRI: can they improve the trade-off between resolution, signal-to-noise ratio, and acquisition time? Magn Reson Med 2012; 68:1983-93. [PMID: 22298247 DOI: 10.1002/mrm.24187] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 11/23/2011] [Accepted: 01/05/2012] [Indexed: 11/09/2022]
Abstract
Improving the resolution in magnetic resonance imaging comes at the cost of either lower signal-to-noise ratio, longer acquisition time or both. This study investigates whether so-called super-resolution reconstruction methods can increase the resolution in the slice selection direction and, as such, are a viable alternative to direct high-resolution acquisition in terms of the signal-to-noise ratio and acquisition time trade-offs. The performance of six super-resolution reconstruction methods and direct high-resolution acquisitions was compared with respect to these trade-offs. The methods are based on iterative back-projection, algebraic reconstruction, and regularized least squares. The algorithms were applied to low-resolution data sets within which the images were rotated relative to each other. Quantitative experiments involved a computational phantom and a physical phantom containing structures of known dimensions. To visually validate the quantitative evaluations, qualitative experiments were performed, in which images of three different subjects (a phantom, an ex vivo rat knee, and a postmortem mouse) were acquired with different magnetic resonance imaging scanners. The results show that super-resolution reconstruction can indeed improve the resolution, signal-to-noise ratio and acquisition time trade-offs compared with direct high-resolution acquisition.
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Affiliation(s)
- Esben Plenge
- Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC-University Medical Center, Rotterdam, Rotterdam, The Netherlands.
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41
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Keeling SL, Clason C, Hintermüller M, Knoll F, Laurain A, von Winckel G. An image space approach to Cartesian based parallel MR imaging with total variation regularization. Med Image Anal 2012; 16:189-200. [DOI: 10.1016/j.media.2011.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 07/05/2011] [Accepted: 07/11/2011] [Indexed: 10/18/2022]
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Cohen-Adad J, Mareyam A, Keil B, Polimeni JR, Wald LL. 32-channel RF coil optimized for brain and cervical spinal cord at 3 T. Magn Reson Med 2011; 66:1198-208. [PMID: 21433068 PMCID: PMC3131444 DOI: 10.1002/mrm.22906] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 01/12/2011] [Accepted: 02/14/2011] [Indexed: 11/09/2022]
Abstract
Diffusion and functional magnetic resonance imaging of the spinal cord remain challenging due to the small cross-sectional size of the cord and susceptibility-related distortions. Although partially addressable through parallel imaging, few highly parallel array coils have been implemented for the cervical cord. Here, we developed a 32-channel coil that fully covers the brain and c-spine and characterized its performance in comparison with a commercially available head/neck/spine array. Image and temporal signal-to-noise ratio were, respectively, increased by 2× and 1.8× in the cervical cord. Averaged g-factors at 4× acceleration were lowered by 22% in the brain and by 39% in the spinal cord, enabling 1-mm isotropic R = 4 multi-echo magnetization prepared gradient echo of the full brain and c-spine in 3:20 min. Diffusion imaging of the cord at 0.6 × 0.6 × 5 mm(3) resolution and tractography of the full brain and c-spine at 1.7-mm isotropic resolution were feasible without noticeable distortion. Improvements of this nature potentially enhance numerous basic and clinical research studies focused on spinal and supraspinal regions.
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Affiliation(s)
- J Cohen-Adad
- AA Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
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Rempp H, Clasen S, Pereira PL. Image-based monitoring of magnetic resonance-guided thermoablative therapies for liver tumors. Cardiovasc Intervent Radiol 2011; 35:1281-94. [PMID: 21785888 DOI: 10.1007/s00270-011-0227-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 06/23/2011] [Indexed: 12/27/2022]
Abstract
Minimally invasive treatment options for liver tumor therapy have been increasingly used during the last decade because their benefit has been proven for primary and inoperable secondary liver tumors. Among these, radiofrequency ablation has gained widespread consideration. Optimal image-guidance offers precise anatomical information, helps to position interventional devices, and allows for differentiation between already-treated and remaining tumor tissue. Patient safety and complete ablation of the entire tumor are the overriding objectives of tumor ablation. These may be achieved most elegantly with magnetic resonance (MR)-guided therapy, where monitoring can be performed based on precise soft-tissue imaging and additional components, such as diffusion-weighted imaging and temperature mapping. New MR scanner types and newly developed sequence techniques have enabled MR-guided intervention to move beyond the experimental phase. This article reviews the current role of MR imaging in guiding radiofrequency ablation. Signal characteristics of primary and secondary liver tumors are identified, and signal alteration during therapy is described. Diffusion-weighted imaging (DWI) and temperature mapping as special components of MR therapy monitoring are introduced. Practical information concerning coils, sequence selection, and parameters, as well as sequence gating, is given. In addition, sources of artifacts are identified and techniques to decrease them are introduced, and the characteristic signs of residual tumor in T1-, T2-, and DWI are described. We hope to enable the reader to choose MR sequences that allow optimal therapy monitoring depending on the initial signal characteristics of the tumor as well as its size and location in the liver.
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Affiliation(s)
- Hansjörg Rempp
- Department of Diagnostic and Interventional Radiology, Eberhard Karls University of Tübingen, 72076, Tübingen, Germany.
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Woodhams R, Ramadan S, Stanwell P, Sakamoto S, Hata H, Ozaki M, Kan S, Inoue Y. Diffusion-weighted Imaging of the Breast: Principles and Clinical Applications. Radiographics 2011; 31:1059-84. [DOI: 10.1148/rg.314105160] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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45
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Enhanced brain connectivity in long-term meditation practitioners. Neuroimage 2011; 57:1308-16. [PMID: 21664467 DOI: 10.1016/j.neuroimage.2011.05.075] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Revised: 04/13/2011] [Accepted: 05/26/2011] [Indexed: 11/23/2022] Open
Abstract
Very little is currently known about the cerebral characteristics that underlie the complex processes of meditation as only a limited number of studies have addressed this topic. Research exploring structural connectivity in meditation practitioners is particularly rare. We thus acquired diffusion tensor imaging (DTI) data of high angular and spatial resolution and used atlas-based tract mapping methods to investigate white matter fiber characteristics in a well-matched sample of long-term meditators and controls (n=54). A broad field mapping approach estimated the fractional anisotropy (FA) for twenty different fiber tracts (i.e., nine tracts in each hemisphere and two inter-hemispheric tracts) that were subsequently used as dependent measures. Results showed pronounced structural connectivity in meditators compared to controls throughout the entire brain within major projection pathways, commissural pathways, and association pathways. The largest group differences were observed within the corticospinal tract, the temporal component of the superior longitudinal fasciculus, and the uncinate fasciculus. While cross-sectional studies represent a good starting point for elucidating possible links between meditation and white matter fiber characteristics, longitudinal studies will be necessary to determine the relative contribution of nature and nurture to enhanced structural connectivity in long-term meditators.
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Çukur T, Lustig M, Saritas EU, Nishimura DG. Signal compensation and compressed sensing for magnetization-prepared MR angiography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2011; 30:1017-27. [PMID: 21335307 PMCID: PMC3156830 DOI: 10.1109/tmi.2011.2116123] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Magnetization-prepared acquisitions offer a trade-off between image contrast and scan efficiency for magnetic resonance imaging. Because the prepared signals gradually decay, the contrast can be improved by frequently repeating the preparation, which in turn significantly increases the scan time. A common solution is to perform the data collection progressing from low- to high-spatial-frequency samples following each preparation. Unfortunately, this leads to loss of spatial resolution, and thereby image blurring. In this work, a new technique is proposed that first corrects the signal decay in high-frequency data to mitigate the resolution loss and improve the image contrast without reducing the scan efficiency. The proposed technique then employs a sparsity-based nonlinear reconstruction to further improve the image quality. In addition to reducing the amplified high-frequency noise, this reconstruction extrapolates missing k-space samples in the case of undersampled compressed-sensing acquisitions. The technique is successfully demonstrated for noncontrast-enhanced flow-independent angiography of the lower extremities, an application that substantially benefits from both the signal compensation and the nonlinear reconstruction.
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Affiliation(s)
- Tolga Çukur
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA.
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Ye X, Chen Y, Lin W, Huang F. Fast MR image reconstruction for partially parallel imaging with arbitrary k-space trajectories. IEEE TRANSACTIONS ON MEDICAL IMAGING 2011; 30:575-585. [PMID: 21356608 DOI: 10.1109/tmi.2010.2088133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Both acquisition and reconstruction speed are crucial for magnetic resonance (MR) imaging in clinical applications. In this paper, we present a fast reconstruction algorithm for SENSE in partially parallel MR imaging with arbitrary k-space trajectories. The proposed method is a combination of variable splitting, the classical penalty technique and the optimal gradient method. Variable splitting and the penalty technique reformulate the SENSE model with sparsity regularization as an unconstrained minimization problem, which can be solved by alternating two simple minimizations: One is the total variation and wavelet based denoising that can be quickly solved by several recent numerical methods, whereas the other one involves a linear inversion which is solved by the optimal first order gradient method in our algorithm to significantly improve the performance. Comparisons with several recent parallel imaging algorithms indicate that the proposed method significantly improves the computation efficiency and achieves state-of-the-art reconstruction quality.
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Affiliation(s)
- Xiaojing Ye
- Department of Mathematics, University of Florida, Gainesville, FL 32611, USA.
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Meurin A, Cernicanu A, Molinier S, Menegon P, Barreau X, Berge J, Dousset V. [Diffusion-weighted MR imaging of the spine and cord]. ACTA ACUST UNITED AC 2010; 91:352-66; quiz 367-8. [PMID: 20508570 DOI: 10.1016/s0221-0363(10)70051-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Due to its excellent sensitivity, MR imaging is invaluable for the evaluation of lesions of the cord and spine. Several studies dedicated to diffusion-weighted MR evaluation of the cord and spine have been published. While diffusion-weighted MR imaging of the brain is routinely performed, it is seldom performed when imaging the spine due to serious limitations. While anatomical limitations may not be changed, the voxel size, phase-encoding direction, mode of k-space filling, and acceleration factor are all parameters that can be optimized in order to routinely obtain diffusion-weighted imaging of the spine on 1.5T and 3T scanners.
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Affiliation(s)
- A Meurin
- Service de neuroradiologie diagnostique et interventionnelle, CHU de Bordeaux, Hôpital Pellegrin-Tripode, place Amélie Raba-Léon, 33076 Bordeaux cedex.
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Cukur T, Santos JM, Pauly JM, Nishimura DG. Variable-density parallel imaging with partially localized coil sensitivities. IEEE TRANSACTIONS ON MEDICAL IMAGING 2010; 29:1173-1181. [PMID: 20236876 PMCID: PMC3155390 DOI: 10.1109/tmi.2010.2042805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Partially parallel imaging with localized sensitivities is a fast parallel image reconstruction method for both Cartesian and non-Cartesian trajectories, but suffers from aliasing artifacts when there are deviations from the assumption of perfect localization. Such reconstructions would normally crop the individual coil images to remove the artifacts prior to combination. However, the sampling densities in variable-density k-space trajectories support different field-of-views for separate regions in k -space. In fact, the higher sampling density of low frequencies can be used to reconstruct a bigger field-of-view without introducing aliasing artifacts and the resulting image signal-to-noise ratio (SNR) can be improved. A novel, fast variable-density parallel imaging method is presented, which reconstructs different field-of-views from separate frequencies according to the local sampling density in k-space. Aliasing-suppressed images can be produced with high SNR-efficiency without the need for accurate estimation of coil sensitivities and complex or iterative computations.
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Affiliation(s)
- Tolga Cukur
- Information Systems Laboratory, Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
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Doria AS, Chaudry GA, Nasui C, Rayner T, Wang C, Moineddin R, Babyn PS, White LM, Sussman MS. The use of parallel imaging for MRI assessment of knees in children and adolescents. Pediatr Radiol 2010; 40:284-93. [PMID: 19949946 DOI: 10.1007/s00247-009-1426-z] [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: 04/27/2009] [Accepted: 09/02/2009] [Indexed: 11/29/2022]
Abstract
BACKGROUND Parallel imaging provides faster scanning at the cost of reduced signal-to-noise ratio (SNR) and increased artifacts. OBJECTIVE To compare the diagnostic performance of two parallel MRI protocols (PPs) for assessment of pathologic knees using an 8-channel knee coil (reference standard, conventional protocol [CP]) and to characterize the SNR losses associated with parallel imaging. MATERIALS AND METHODS Two radiologists blindly interpreted 1.5 Tesla knee MRI images in 21 children (mean 13 years, range 9-18 years) with clinical indications for an MRI scan. Sagittal proton density, T2-W fat-saturated FSE, axial T2-W fat-saturated FSE, and coronal T1-W (NEX of 1,1,1) images were obtained with both CP and PP. Images were read for soft tissue and osteochondral findings. RESULTS There was a 75% decrease in acquisition time using PP in comparison to CP. The CP and PP protocols fell within excellent or upper limits of substantial agreement: CP, kappa coefficient, 0.81 (95% CIs, 0.73-0.89); PP, 0.80-0.81 (0.73-0.89). The sensitivity of the two PPs was similar for assessment of soft (0.98-1.00) and osteochondral (0.89-0.94) tissues. Phantom data indicated an SNR of 1.67, 1.6, and 1.51 (axial, sagittal and coronal planes) between CP and PP scans. CONCLUSION Parallel MRI provides a reliable assessment for pediatric knees in a significantly reduced scan time without affecting the diagnostic performance of MRI.
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