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Prince MR. Editorial for "Assessment of Complex Flow Patterns in Patients With Carotid Webs, Patients With Carotid Atherosclerosis, and Healthy Subjects Using 4D Flow MRI". J Magn Reson Imaging 2024; 59:2011-2012. [PMID: 37698383 DOI: 10.1002/jmri.29011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 09/13/2023] Open
Affiliation(s)
- Martin R Prince
- Department of Radiology, Weill Cornell Medicine, New York City, New York, USA
- Department of Radiology, Columbia University Irving Medical Center, New York, USA
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Edelman RR, Ozturk O, Pursnani A, Balasubramanian S, Leloudas N, Koktzoglou I. Equilibrium Phase Contrast-Enhanced MR Angiography of the Thoracic Aorta and Heart using Balanced T1 Relaxation-Enhanced Steady-State (bT1RESS). J Cardiovasc Magn Reson 2024:101046. [PMID: 38810732 DOI: 10.1016/j.jocmr.2024.101046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/29/2024] [Accepted: 05/23/2024] [Indexed: 05/31/2024] Open
Abstract
BACKGROUND Three-dimensional (3D) contrast-enhanced MR angiography (CEMRA) is routinely used for vascular evaluation. With existing techniques for CEMRA, diagnostic image quality is only obtained during the first pass of the contrast agent or shortly thereafter, whereas angiographic quality tends to be poor when imaging is delayed to the equilibrium phase. We hypothesized that prolonged blood pool contrast enhancement could be obtained by imaging with a balanced T1 relaxation-enhanced steady-state (bT1RESS) pulse sequence, which combines 3D balanced steady-state free precession (bSSFP) with a saturation recovery magnetization preparation to impart T1 weighting and suppress background tissues. An electrocardiographic (ECG)-gated, 2D-accelerated version with isotropic 1.1-mm spatial resolution was evaluated for breath-hold equilibrium phase CEMRA of the thoracic aorta and heart. Main body The study was IRB approved. 21 subjects were imaged using unenhanced 3D bSSFP, time-resolved CEMRA, first pass gated CEMRA, followed by early and late equilibrium phase gated CEMRA and bT1RESS. 9 additional subjects were imaged using equilibrium phase 3D bSSFP and bT1RESS. Images were evaluated for image quality, aortic root sharpness, and visualization of the coronary artery origins, as well as using standard quantitative measures. RESULTS Equilibrium phase bT1RESS provided better image quality, aortic root sharpness, and coronary artery origin visualization than gated CEMRA (P<0.05), and improved image quality and aortic root sharpness versus unenhanced 3D bSSFP (P<0.05). It provided significantly larger apparent signal-to-noise and apparent contrast-to-noise ratio values than gated CEMRA and unenhanced 3D bSSFP (P<0.05) and provided ninefold better fluid suppression than equilibrium phase 3D bSSFP. Aortic diameter and main pulmonary artery diameter measurements obtained with bT1RESS and first pass gated CEMRA strongly correlated (P<0.05). DISCUSSION AND CONCLUSION We found that using bT1RESS greatly prolongs the useful duration of blood pool contrast enhancement while improving angiographic image quality compared with standard CEMRA techniques. Although further study is needed, potential advantages for vascular imaging include eliminating the current requirement for first pass imaging along with better reliability and accuracy for a wide range of cardiovascular applications.
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Affiliation(s)
- Robert R Edelman
- Radiology, Northshore University HealthSystem, Evanston, Illinois, USA; Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
| | - Onural Ozturk
- Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
| | - Amit Pursnani
- Radiology, Northshore University HealthSystem, Evanston, Illinois, USA; Medicine, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA.
| | | | - Nondas Leloudas
- Radiology, Northshore University HealthSystem, Evanston, Illinois, USA.
| | - Ioannis Koktzoglou
- Radiology, Northshore University HealthSystem, Evanston, Illinois, USA; Radiology, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA.
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Goldfarb JW, Mossa-Basha M, Nguyen KL, Hecht EM, Finn JP. Trends in magnetic resonance and computed tomography angiography utilization among Medicare beneficiaries between 2013 and 2020. Clin Imaging 2024; 107:110088. [PMID: 38277858 DOI: 10.1016/j.clinimag.2024.110088] [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: 09/22/2023] [Revised: 01/11/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024]
Abstract
PURPOSE To evaluate relative and absolute utilization trends and practice patterns in the United States for MRA and CTA. METHODS Using Medicare Part B physician payment databases (2013-2020), MRA and CTA interpreting physicians and exams were identified using the unique MRA and CTA Healthcare Common Procedure Coding System codes. The number of exams, physicians, demographics, use of contrast, and payments were summarized annually and analyzed to evaluate trends before and during the first year of the COVID-19 pandemic. RESULTS From 2013 to 2019, the annual number of MRA exams performed decreased by 17.9 %, while the number of CTA exams increased by 90.3 %. The number of physicians interpreting MRA decreased in both hospital (-17.2 %) and outpatient (-7.5 %) environments. The number of physicians interpreting CTA increased in both hospital (+29.4 %) and outpatient (+54.3 %) environments. During the first year of the COVID-19 pandemic, MRA utilization decreased across all imaging environments by 25.0 % whereas CTA only decreased by 5.5 %. Intracranial MRA studies were most often performed without contrast, while contrast use for neck MRA was performed at similar rates as non-contrast exams. CONCLUSION The overall utilization of MRA and the number of interpreting physicians are decreasing. On the other hand, CTA use and its number of interpreting physicians are increasing. During the first year of the COVID-19 pandemic, use of both MRA and CTA decreased, but the utilization of MRA decreased at five times the rate of CTA.
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Affiliation(s)
- James W Goldfarb
- Division of Cardiovascular Imaging, St. Francis Hospital and Heart Center, Roslyn, NY, USA.
| | - Mahmud Mossa-Basha
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kim-Lien Nguyen
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Division of Cardiology, David Geffen School of Medicine at UCLA, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | | | - J Paul Finn
- Diagnostic Cardiovascular Imaging Research Laboratory, Department of Radiological Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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Nagpal P, Grist TM. MR Angiography: Contrast-Enhanced Acquisition Techniques. Magn Reson Imaging Clin N Am 2023; 31:493-501. [PMID: 37414474 DOI: 10.1016/j.mric.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
Contrast-enhanced MR angiography (CE-MRA) is a frequently used MR imaging technique for evaluating cardiovascular structures. In many ways, it is similar to contrast-enhanced computed tomography (CT) angiography, except a gadolinium-based contrast agent (instead of iodinated contrast) is injected. Although the physiological principles of contrast injection overlap, the technical factors behind enhancement and image acquisition are different. CE-MRA provides an excellent alternative to CT for vascular evaluation and follow-up without requiring nephrotoxic contrast and ionizing radiation. This review describes the physical principles, limitations, and technical applications of CE-MRA techniques.
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Affiliation(s)
- Prashant Nagpal
- Cardiovascular Imaging, Department of Radiology, University of Wisconsin-Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53705, USA.
| | - Thomas M Grist
- Radiology, University of Wisconsin Madison, E3/366 600 Highland Avenue, Madison, WI 53792, USA
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Wang Y, Liu X, Wang Y, Qi H, Liu X, Kong X, Zhang Q, Dou J, Wang J, Chen H. Optimization of the Contrast Agent Injection Protocol for Carotid Artery Dynamic Contrast-Enhanced Magnetic Resonance Imaging. J Magn Reson Imaging 2022; 56:1372-1381. [PMID: 35324034 DOI: 10.1002/jmri.28175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/11/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The injection protocol used in previous carotid artery dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) studies varied. PURPOSE To investigate the effect of contrast injection protocol and optimize this protocol for carotid artery DCE-MRI. STUDY TYPE Prospective. SUBJECTS Digital phantom and seven patients with carotid atherosclerosis. FIELD STRENGTH/SEQUENCE 3 T, spoiled gradient recalled echo sequence. ASSESSMENT Different injection doses (0.01-0.3 mmol/kg) and effective injection rates (0.01-1 mmol/sec) were tested using a digital carotid plaque phantom considering the contrast pharmacokinetics, DCE-MRI imaging, contrast variation and flow-related imaging artifacts, random time delay between the contrast injection and image acquisition, and pharmacokinetic analysis process. For each injection protocol, combining the root mean square relative error (RMSRE) of the measured K trans and v P maps within the adventitial vasa vasorum from 10 tested time delays by the root mean square produced RMSREoverall-vv which was used to measure the overall accuracy of the pharmacokinetic parameters. In vivo validation was performed on seven patients with carotid atherosclerosis by imaging them twice using the traditional commonly used protocol and the recommended protocol found by simulation. STATISTICAL TEST Student's t-test, chi-square test, and paired t-test, P < 0.05 was considered statistically significant. RESULTS A low region of RMSREoverall-vv with the combination of medium injection dose and low effective injection rate was found. The protocol with injection dose of 0.07 mmol/kg and effective injection rate of 0.06 mmol/sec achieved the minimal RMSREoverall-vv (4.29%), thus was recommended, which showed more accurate arterial input function. Coinciding with the simulation results, this recommended protocol in in vivo experiments produced significantly fewer image artifacts, lower K trans and v P (P all <0.05) than traditional protocol which overestimated these parameters in simulation. DATA CONCLUSION The contrast injection protocol influenced the accuracy of the pharmacokinetics parameter estimation in carotid artery DCE-MRI. The injection protocol with injection dose of 0.07 mmol/kg and effective injection rate of 0.06 mmol/sec was recommended. LEVEL OF EVIDENCE 2 TECHNICAL EFFICACY STAGE: 1.
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Affiliation(s)
- Yajie Wang
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Xiaoming Liu
- Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Hubei Province Key Laboratory of Molecular Imaging, Wuhan, Hubei, China
| | | | - Haikun Qi
- School of Biomedical Engineering, ShanghaiTech University, Shanghai, China
| | - Xian Liu
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Xiangchuang Kong
- Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Hubei Province Key Laboratory of Molecular Imaging, Wuhan, Hubei, China
| | - Qiang Zhang
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Jiaqi Dou
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Jing Wang
- Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Hubei Province Key Laboratory of Molecular Imaging, Wuhan, Hubei, China
| | - Huijun Chen
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
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Yamada T, Masui T, Sasaki M, Katayama M, Iwadate Y, Takei N, Miyoshi M. Time resolved DCE-MRI of the kidneys: Evaluation of the renal vasculatures and tumors using F-DISCO with and without compressed sensing in normal and wide-bore 3T systems. Medicine (Baltimore) 2022; 101:e29971. [PMID: 35945778 PMCID: PMC9351894 DOI: 10.1097/md.0000000000029971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Dynamic contrast-enhanced MR imaging (DCE-MRI) has been widely used for the evaluation of renal arteries. This method is also useful for tumor and renal parenchyma characterization. The very fast MRI may provide stable and precise information regarding vasculature and soft tissues. The purpose of this study was to evaluate the ability of DCE-MRI to assess renal vasculatures and tumor perfusions using Differential subsampling with Cartesian ordering with spectrally selected inversion recovery with adiabatic pulses (F-DISCO) with and without compressed sensing (CS) in normal and wide-bore 3T systems. Fifty-one patients who underwent DCE-MRI using F-DISCO with or without CS for evaluation of renal or adrenal regions were included. Image quality, artifacts, fat saturation, and selective visual recognition of renal vasculatures were assessed by using a 5-point scale. Tumor recognition was verified by using a 5-point scale of confidence level. Signal intensities of each structure were also measured. In all cases, the temporal resolution of each phase for DCE-MRI was 1.9 to 2.0 seconds. Image quality, artifacts, fat saturation, and selective visual recognition of vasculatures were all acceptable (mean score 4.2-4.9). The selective visualization of renal arteries and veins was successfully accomplished (mean score 4.0-4.9). Contrast media perfusion for renal vasculature, renal parenchyma, and tumors was also recognized. DCE-MRI for the evaluation of renal vasculatures and tumors using F-DISCO with or without CS can be performed with high temporal and spatial resolutions in normal and wide-bore 3T systems. This information can be obtained in a stable fashion throughout the dynamic contrast study. CS can additionally provide benefits that the total imaging time may be shorter than without CS.
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Affiliation(s)
- Takahiro Yamada
- Department of Radiology, Seirei Hamamatsu General Hospital, Hamamatsu, Shizuoka, Japan
| | - Takayuki Masui
- Department of Radiology, Seirei Hamamatsu General Hospital, Hamamatsu, Shizuoka, Japan
- *Correspondence: Takayuki Masui, MD, PhD, Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Naka-district, Hamamatsu, Shizuoka 430-8558, Japan (e-mail )
| | - Masako Sasaki
- Department of Radiology, Seirei Hamamatsu General Hospital, Hamamatsu, Shizuoka, Japan
| | - Motoyuki Katayama
- Department of Radiology, Seirei Hamamatsu General Hospital, Hamamatsu, Shizuoka, Japan
| | - Yuji Iwadate
- Global MR Applications and Workflow, GE Healthcare Japan, Hino, Tokyo, Japan
| | - Naoyuki Takei
- Global MR Applications and Workflow, GE Healthcare Japan, Hino, Tokyo, Japan
| | - Mitsuharu Miyoshi
- Global MR Applications and Workflow, GE Healthcare Japan, Hino, Tokyo, Japan
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de Buck MHS, Jezzard P, Hess AT. Optimization of undersampling parameters for 3D intracranial compressed sensing MR angiography at 7 T. Magn Reson Med 2022; 88:880-889. [PMID: 35344622 PMCID: PMC9314035 DOI: 10.1002/mrm.29236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 01/26/2023]
Abstract
Purpose 3D time‐of‐flight MRA can accurately visualize the intracranial vasculature but is limited by long acquisition times. Compressed sensing reconstruction can be used to substantially accelerate acquisitions. The quality of those reconstructions depends on the undersampling patterns used. In this work, we optimize sets of undersampling parameters for various acceleration factors of Cartesian 3D time‐of‐flight MRA. Methods Fully sampled datasets, acquired at 7 Tesla, were retrospectively undersampled using variable‐density Poisson disk sampling with various autocalibration region sizes, polynomial orders, and acceleration factors. The accuracy of reconstructions from the different undersampled datasets was assessed using the vessel‐masked structural similarity index. Identified optimal undersampling parameters were then evaluated in additional prospectively undersampled datasets. Compressed sensing reconstruction parameters were chosen based on a preliminary reconstruction parameter optimization. Results For all acceleration factors, using a fully sampled calibration area of 12 × 12 k‐space lines and a polynomial order of 2 resulted in the highest image quality. The importance of parameter optimization of the sampling was found to increase for higher acceleration factors. The results were consistent across resolutions and regions of interest with vessels of varying sizes and tortuosity. The number of visible small vessels increased by 7.0% and 14.2% when compared to standard parameters for acceleration factors of 7.2 and 15, respectively. Conclusion The image quality of compressed sensing time‐of‐flight MRA can be improved by appropriate choice of undersampling parameters. The optimized sets of parameters are independent of the acceleration factor and enable a larger number of vessels to be visualized.
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Affiliation(s)
- Matthijs H S de Buck
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Peter Jezzard
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Aaron T Hess
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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8
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Contrast-enhanced body magnetic resonance angiography: how we do it. Pediatr Radiol 2022; 52:262-270. [PMID: 33978803 DOI: 10.1007/s00247-021-05020-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/30/2020] [Accepted: 02/11/2021] [Indexed: 10/21/2022]
Abstract
This review introduces the basic principles of contrast-enhanced magnetic resonance (MR) angiography and details four contrast-enhanced MR angiography sequences for body imaging with extracellular gadolinium-based contrast agents in pediatric patients. Specifically, this review covers (1) respiratory-navigated, cardiac-gated MR angiography; (2) time-resolved MR angiography; (3) conventional MR angiography; and (4) modified spoiled gradient echo variants. We present and discuss indications, technical considerations, sequence optimization, advantages and disadvantages, along with practical tips and illustrative case examples for each sequence.
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Montalt-Tordera J, Quail M, Steeden JA, Muthurangu V. Reducing Contrast Agent Dose in Cardiovascular MR Angiography with Deep Learning. J Magn Reson Imaging 2021; 54:795-805. [PMID: 33619859 PMCID: PMC9681557 DOI: 10.1002/jmri.27573] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/05/2021] [Accepted: 02/09/2021] [Indexed: 12/26/2022] Open
Abstract
Background Contrast‐enhanced magnetic resonance angiography (MRA) is used to assess various cardiovascular conditions. However, gadolinium‐based contrast agents (GBCAs) carry a risk of dose‐related adverse effects. Purpose To develop a deep learning method to reduce GBCA dose by 80%. Study Type Retrospective and prospective. Population A total of 1157 retrospective and 40 prospective congenital heart disease patients for training/validation and testing, respectively. Field Strength/Sequence A 1.5 T, T1‐weighted three‐dimensional (3D) gradient echo. Assessment A neural network was trained to enhance low‐dose (LD) 3D MRA using retrospective synthetic data and tested with prospective LD data. Image quality for LD (LD‐MRA), enhanced LD (ELD‐MRA), and high‐dose (HD‐MRA) was assessed in terms of signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and a quantitative measure of edge sharpness and scored for perceptual sharpness and contrast on a 1–5 scale. Diagnostic confidence was assessed on a 1–3 scale. LD‐ and ELD‐MRA were assessed against HD‐MRA for sensitivity/specificity and agreement of vessel diameter measurements (aorta and pulmonary arteries). Statistical Tests SNR, CNR, edge sharpness, and vessel diameters were compared between LD‐, ELD‐, and HD‐MRA using one‐way repeated measures analysis of variance with post‐hoc t‐tests. Perceptual quality and diagnostic confidence were compared using Friedman's test with post‐hoc Wilcoxon signed‐rank tests. Sensitivity/specificity was compared using McNemar's test. Agreement of vessel diameters was assessed using Bland–Altman analysis. Results SNR, CNR, edge sharpness, perceptual sharpness, and perceptual contrast were lower (P < 0.05) for LD‐MRA compared to ELD‐MRA and HD‐MRA. SNR, CNR, edge sharpness, and perceptual contrast were comparable between ELD and HD‐MRA, but perceptual sharpness was significantly lower. Sensitivity/specificity was 0.824/0.921 for LD‐MRA and 0.882/0.960 for ELD‐MRA. Diagnostic confidence was 2.72, 2.85, and 2.92 for LD, ELD, and HD‐MRA, respectively (PLD‐ELD, PLD‐HD < 0.05). Vessel diameter measurements were comparable, with biases of 0.238 (LD‐MRA) and 0.278 mm (ELD‐MRA). Data Conclusion Deep learning can improve contrast in LD cardiovascular MRA. Level of Evidence Level 2 Technical Efficacy Stage 2
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Affiliation(s)
- Javier Montalt-Tordera
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science, University College London, London, WC1N 1EH, UK
| | - Michael Quail
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science, University College London, London, WC1N 1EH, UK.,Great Ormond Street Hospital, London, WC1N 3JH, UK
| | - Jennifer A Steeden
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science, University College London, London, WC1N 1EH, UK
| | - Vivek Muthurangu
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science, University College London, London, WC1N 1EH, UK
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Settecase F, Rayz VL. Advanced vascular imaging techniques. HANDBOOK OF CLINICAL NEUROLOGY 2021; 176:81-105. [DOI: 10.1016/b978-0-444-64034-5.00016-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Yoneyama M, Zhang S, Hu HH, Chong LR, Bardo D, Miller JH, Toyonari N, Katahira K, Katsumata Y, Pokorney A, Ng CK, Kouwenhoven M, Van Cauteren M. Free-breathing non-contrast-enhanced flow-independent MR angiography using magnetization-prepared 3D non-balanced dual-echo Dixon method: A feasibility study at 3 Tesla. Magn Reson Imaging 2019; 63:137-146. [DOI: 10.1016/j.mri.2019.08.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/18/2019] [Accepted: 08/15/2019] [Indexed: 11/30/2022]
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Marasini R, Thanh Nguyen TD, Aryal S. Integration of gadolinium in nanostructure for contrast enhanced-magnetic resonance imaging. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2019; 12:e1580. [PMID: 31486295 DOI: 10.1002/wnan.1580] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/18/2019] [Accepted: 07/24/2019] [Indexed: 01/10/2023]
Abstract
Magnetic resonance imaging (MRI) is a routinely used imaging technique in medical diagnostics, which is further enhanced with the use of contrast agents (CAs). The most commonly used CAs are gadolinium-based contrast agents (GBCAs), in which gadolinium (Gd) is chelated with organic chelating agents (linear or cyclic). However, the use of GBCA is related to toxic side effect due to the release of free Gd3+ ions from the chelating agents. The repeated use of GBCAs has led to Gd deposition in various major organs including bone, brain, and kidneys. As a result, the use of GBCA has been linked to the development of nephrogenic systemic fibrosis (NSF). Due to the GBCA associated toxicities, some clinically approved GBCAs have been limited or revoked recently. Therefore, there is an urgent need for the development of new strategies to chelate and stabilize Gd3+ ions for contrast enhancement, safety profile, and selective imaging of a pathological site. Toward this endeavor, GBCAs have been engineered using different nanoparticulate systems to improve their stability, biocompatibility, and pharmacokinetics. Throughout this review, some of the important strategies for engineering small molecular Gd3+ chelates into a nanoconstruct is discussed. We focus on the development of GBCAs as liposomes, mesoporous silica nanoparticles (MSNs), polymeric nanocarriers, and plasmonic nanoparticles-based design strategies to improve safety and contrast enhancement for contrast enhanced-magnetic resonance imaging (Ce-MRI). We also discuss the in-vitro/in-vivo properties of strategically designed nanoscale MRI CAs, its potentials, and limitations. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Diagnostic Tools > Diagnostic Nanodevices Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.
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Affiliation(s)
- Ramesh Marasini
- Department of Chemistry, Kansas State University, Manhattan, Kansas.,Nanotechnology Innovation Center of Kansas State (NICKS), Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Tuyen Duong Thanh Nguyen
- Department of Chemistry, Kansas State University, Manhattan, Kansas.,Nanotechnology Innovation Center of Kansas State (NICKS), Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Santosh Aryal
- Department of Chemistry, Kansas State University, Manhattan, Kansas.,Nanotechnology Innovation Center of Kansas State (NICKS), Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Maki JH, Wilson GJ, Clark TJ. Evaluation of four injection profiles for uniform contrast-enhanced signal intensity profiles in MR angiography. J Magn Reson Imaging 2019; 50:1808-1816. [PMID: 31095810 DOI: 10.1002/jmri.26793] [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] [Received: 03/14/2019] [Revised: 05/03/2019] [Accepted: 05/03/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Gadolinium concentration variation during acquisition of contrast-enhanced MR angiography (CE-MRA) may lead to artifacts. PURPOSE To compare signal intensity (SI) profiles of four different contrast agent injection strategies during CE-MRA with the goal of minimizing SI variation during acquisition. STUDY TYPE Prospective. SUBJECTS Forty subjects randomized to receive one of four injection profiles of gadobenate dimeglumine (0.1 mmol/kg), either undiluted (0.5 M) or diluted to 40 ml total volume. Tested profiles: 1) nondiluted single-phase ("standard" NS; 1.6 ml/s), 2) diluted single-phase (DS; 1.6 ml/s), 3) diluted biphasic (DB; 9 ml @ 3.3 ml/s, 29 ml @ 1.4 ml/s), 4) patient-tailored protocol using linear prediction (DT). FIELD STRENGTH/SEQUENCE Time-resolved SI measured at 3T with spoiled gradient echo sequences having analogous parameters to those of CE-MRA. ASSESSMENT Plateau arrival time, rise time, duration, peak and tail SI, plateau quality (sum of squared residuals; SSR), average SI for each injection type derived were used. STATISTICAL TEST Two-tailed t-test. RESULTS Peak SI, arrival, and rise times were not significantly different between groups, excepting peak SI DB slightly > DS (P = 0.042). Duration of NS vs. the diluted groups was significantly shorter (all P < 0.0001), and DS duration was significantly shorter than that of DT and DB (NS 11.4 ± 3.5 vs. DS 22.9 ± 4.3, DB 25.4 ± 2.3, DT 28.3 ± 4.1 sec). Quality (SSR) of the 20-second plateau was significantly better for DS, DB, DT as compared with NS (all P < 0.001). DATA CONCLUSION Three different strategies to power-inject diluted gadobenate dimeglumine targeting a 20-second plateau produced SI profiles with longer duration, more consistent plateau, and no significant loss in peak SI. Such injection profiles may provide more uniform SI during CE-MRA, potentially reducing blurring artifacts. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1808-1816.
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Affiliation(s)
- Jeffrey H Maki
- The Department of Radiology, University of Colorado Denver, Aurora, Colorado, USA.,Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Gregory J Wilson
- Department of Radiology, University of Washington, Seattle, Washington, USA.,Bayer Healthcare, Whippany, New Jersey, USA
| | - Toshimasa J Clark
- The Department of Radiology, University of Colorado Denver, Aurora, Colorado, USA
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Shin T, Menon RG, Thomas RB, Cavallo AU, Sarkar R, Crawford RS, Rajagopalan S. Unenhanced Velocity-Selective MR Angiography (VS-MRA): Initial Clinical Evaluation in Patients With Peripheral Artery Disease. J Magn Reson Imaging 2019; 49:744-751. [PMID: 30211442 PMCID: PMC6375774 DOI: 10.1002/jmri.26268] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/06/2018] [Accepted: 07/06/2018] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Safe and accurate imaging of the peripheral arterial system is important for diagnosis and treatment planning of patients with peripheral artery disease (PAD). PURPOSE To evaluate image quality and diagnostic performance of unenhanced magnetic resonance angiography (MRA) based on velocity-selective (VS) magnetization preparation (termed VS-MRA). STUDY TYPE Prospective. POPULATION Thirty-one symptomatic PAD patients underwent VS-MRA. Twenty-four of them underwent clinical digital subtraction angiography (DSA) examination, 18.8 ± 5.2 days after the MR scans. FIELD STRENGTH/SEQUENCE 1.5T MRI that included VS-MRA (homemade research sequence) and phase-contrast flow imaging (clinical sequence). ASSESSMENT Image quality (0: nondiagnostic, 3: excellent) and stenosis severity (0: normal, 3: occlusion) of VS-MRA images were assessed independently by three reviewers. Arterial signal-to-noise-ratio (SNR) and artery-to-muscle contrast-to-noise ratio (CNR) were calculated. STATISTICAL TESTS The sensitivity and specificity of VS-MRA were calculated for the detection of significant stenosis (>50%) with DSA as the reference standard. Interobserver agreement among the three reviewers was evaluated by using Cohen κ-statistics. RESULTS The image quality score of VS-MRA was 2.7 ± 0.5 for Reader 1, 2.8 ± 0.5 for Reader 2, and 2.8 ± 0.4 for Reader 3; SNR and CNR were 37.8 ± 12.5 and 30.5 ± 11.8, respectively. Segment-based analysis revealed that VS-MRA had sensitivities of 85.3%, 74.5%, and 78.4%, respectively, for the three reviewers, and specificities of 93.5%, 96.8%, and 95.2%. The interobserver agreement for the stenosis grading was good, as demonstrated by Cohen κ values of 0.76 (Reader 1 vs. Reader 2), 0.82 (Reader 1 vs. Reader 3), and 0.79 (Reader 2 vs. Reader 3). DATA CONCLUSION Unenhanced VS-MRA allows clear depiction of the peripheral arteries and accurate stenosis grading, as evidenced by high image quality scores and strong agreement with DSA. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:744-751.
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Affiliation(s)
- Taehoon Shin
- Division of Mechanical and Biomedical Engineering, Ewha Womans University, Seoul, South Korea
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, Maryland
| | - Rajiv G. Menon
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, Maryland
- Department of Radiology, New York University, New York, New York
| | - Rahul B. Thomas
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Armando U. Cavallo
- Diagnostic and Interventional Radiology Division, University Hospital Policlinico “Tor Vergata”, Rome, Italy
| | - Rajabraka Sarkar
- Division of Vascular and Endovascular Surgery, University of Maryland, Baltimore, Maryland
| | - Robert S. Crawford
- Division of Vascular and Endovascular Surgery, University of Maryland, Baltimore, Maryland
| | - Sanjay Rajagopalan
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio
- Division of Cardiovascular Medicine, University of Maryland, Baltimore, Maryland
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Raptis CA, Ludwig DR, Hammer MM, Luna A, Broncano J, Henry TS, Bhalla S, Ackman JB. Building blocks for thoracic MRI: Challenges, sequences, and protocol design. J Magn Reson Imaging 2019; 50:682-701. [PMID: 30779459 DOI: 10.1002/jmri.26677] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/18/2019] [Accepted: 01/19/2019] [Indexed: 12/19/2022] Open
Abstract
Thoracic MRI presents important and unique challenges. Decreased proton density in the lung in combination with respiratory and cardiac motion can degrade image quality and render poorly executed sequences uninterpretable. Despite these challenges, thoracic MRI has an important clinical role, both as a problem-solving tool and in an increasing array of clinical indications. Advances in scanner and sequence design have also helped to drive this development, presenting the radiologist with improved techniques for thoracic MRI. Given this evolving landscape, radiologists must be familiar with what thoracic MR has to offer. The first step in developing an effective thoracic MRI practice requires the creation of efficient and malleable protocols that can answer clinical questions. To do this, radiologists must have a working knowledge of the MR sequences that are used in the thorax, many of which have been adapted from use elsewhere in the body. These sequences can be broadly divided into three categories: traditional/anatomic, functional, and cine based. Traditional/anatomic sequences allow for the depiction of anatomy and pathologic processes with the ability for characterization of signal intensity and contrast enhancement. Functional sequences, including diffusion-weighted imaging, and high temporal resolution dynamic contrast enhancement, allow for the noninvasive measurement of tissue-specific parameters. Cine-based sequences can depict the motion of structures in the thorax, either with retrospective ECG gating or in real time. The purpose of this article is to review these categories, the building block sequences that comprise them, and identify basic questions that should be considered in thoracic MRI protocol design. Level of Evidence: 5 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:682-701.
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Affiliation(s)
| | - Daniel R Ludwig
- Mallinckrodt Institute of Radiology, St. Louis, Missouri, USA
| | - Mark M Hammer
- Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Antonio Luna
- Health Time, Clinica Las Nieves, Jaen, Spain.,University Hospitals, Case Western Reserve University, Cleveland, Ohio, USA
| | - Jordi Broncano
- Health Time, Hospital de la Cruz Roja and San Juan de Dios, Cordoba, Spain
| | - Travis S Henry
- University of California-San Francisco, San Francisco, California, USA
| | - Sanjeev Bhalla
- Mallinckrodt Institute of Radiology, St. Louis, Missouri, USA
| | - Jeanne B Ackman
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Fathi MF, Bakhshinejad A, Baghaie A, Saloner D, Sacho RH, Rayz VL, D’Souza RM. Denoising and spatial resolution enhancement of 4D flow MRI using proper orthogonal decomposition and lasso regularization. Comput Med Imaging Graph 2018; 70:165-172. [DOI: 10.1016/j.compmedimag.2018.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 04/17/2018] [Accepted: 07/24/2018] [Indexed: 11/15/2022]
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Bayat M, Fatemi M, Alizad A. Background Removal and Vessel Filtering of Noncontrast Ultrasound Images of Microvasculature. IEEE Trans Biomed Eng 2018; 66:831-842. [PMID: 30040621 DOI: 10.1109/tbme.2018.2858205] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Recent advances in ultrasound Doppler imaging have made it possible to visualize small vessels with diameters near the imaging resolution limits using spatiotemporal singular value thresholding of long ensembles of ultrasound data. However, vessel images derived based on this method present severe intensity variations and additional background noise that limits visibility and subsequent processing such as centerline extraction and morphological analysis. The goal of this paper is to devise a method to enhance vessel-background separation directly on the power Doppler images by exploiting blood echo-noise independence. METHOD We present a two-step algorithm to mitigate these adverse effects when using singular value thresholding for obtaining gross vasculature images. Our method comprises a morphological-based filtering for removing global and local background signals and a multiscale Hessian-based vessel enhancement filtering to further improve the vascular structures. We applied our method for in vivo imaging of the microvasculature of kidney in one healthy subject, liver in five healthy subjects, thyroid nodules in five patients, and breast tumors in five patients. RESULTS Singular value thresholding, top-hat filtering, and Hessian-based vessel enhancement filtering each provided an average peak-to-side level gain of 1.11, 18.55, and 2.26 dB, respectively, resulting in an overall gain of 21.92 dB when compared to the conventional power Doppler imaging using infinite impulse response filtering. CONCLUSION Singular value thresholding combined with morphological and Hessian-based vessel enhancement filtering provides a powerful tool for visualization of the deep-seated small vessels using long ultrasound echo ensembles without requiring any type of contrast enhancing agents. SIGNIFICANCE This method provides a fast and cost-effective modality for in vivo assessment of the microvasculature suitable for both clinical and preclinical applications.
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Accuracy and Repeatability of Automated Injector Versus Manual Administration of an MRI Contrast Agent-Results of a Laboratory Study. Invest Radiol 2018; 53:1-5. [PMID: 28796722 PMCID: PMC5728584 DOI: 10.1097/rli.0000000000000403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this study was to compare flow rates over time and the deviations from the target flow rate of a magnetic resonance imaging contrast agent achieved by an automated injector versus manual injection. MATERIALS AND METHODS In this laboratory study, the magnetic resonance contrast agent gadobutrol was repeatedly injected by an injector and by 10 experienced technologists. Six scenarios with 2 different target flow rates (1 and 5 mL/s), 2 different contrast volumes (10 and 20 mL), and 2 different intravenous (IV) catheters (22 gauge and 20 gauge) were tested. The flow rates over time were recorded. The target variable was the average absolute deviation and average absolute percentage deviation from the target flow rate. RESULTS The flow rates over time achieved by an injector were almost identical. Slight deviations from the target flow rate occurred during ramp-up and ramp-down only. Those of manual injection showed high variability over the whole course of the injection. In the 1 mL/s scenarios, the injector deviated from the target flow rate by 0.06 mL/s or less (≤6%) and in the 5 mL/s scenarios by 1.02 mL/s or less (<20%). For the manual injections at the same flow rates, these figures were 0.35 mL/s or less (≤35%) and 3.1 mL/s or less (≤62%). CONCLUSIONS Injector administration of a magnetic resonance contrast agent minimally deviated from the target flow rate, whereas manual injection varied widely. Injector administration is more accurate and repeatable.
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Çildağ MB, Ertuğrul MB, Köseoğlu ÖF, Armstrong DG. A Factor Increasing Venous Contamination on Bolus Chase Three-dimensional Magnetic Resonance Imaging: Charcot Neuroarthropathy. J Clin Imaging Sci 2018; 8:13. [PMID: 29682401 PMCID: PMC5898191 DOI: 10.4103/jcis.jcis_77_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 03/08/2018] [Indexed: 11/04/2022] Open
Abstract
Background The study aimed to evaluate the ratio of venous contamination in diabetic cases without foot lesion, with foot lesion and with Charcot neuroarthropathy (CN). Materials and Methods Bolus-chase three-dimensional magnetic resonance (MR) of 396 extremities of patients with diabetes mellitus was analyzed, retrospectively. Extremities were divided into three groups as follows: diabetic patients without foot ulcer or Charcot arthropathy (Group A), patients with diabetic foot ulcers (Group B) and patients with CN accompanying diabetic foot ulcers (Group C). Furthermore, amount of venous contamination classified as no venous contamination, mild venous contamination, and severe venous contamination. The relationship between venous contamination and extremity groups was investigated. Results Severe venous contamination was seen in Group A, Group B, and Group C, 5.6%, 15.2%, and 34.1%, respectively. Statistically significant difference was seen between groups with regard to venous contamination. Conclusion Venous contamination following bolus chase MR was higher in patients with CN.
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Affiliation(s)
- Mehmet B Çildağ
- Department of Diagnostic and Interventional Radiology, Adnan Menderes University, Aydin, Turkey
| | - Mustafa B Ertuğrul
- Infectious Diseases and Clinical Microbiology, Adnan Menderes University, Aydin, Turkey
| | - Ömer Fk Köseoğlu
- Department of Diagnostic and Interventional Radiology, Adnan Menderes University, Aydin, Turkey
| | - David G Armstrong
- Department of Surgery, Southern Arizona Limb Salvage Alliance, University of Arizona College of Medicine, Tucson, Ariz, USA
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Nitta N, Takakusagi Y, Kokuryo D, Shibata S, Tomita A, Higashi T, Aoki I, Harada M. Intratumoral evaluation of 3D microvasculature and nanoparticle distribution using a gadolinium-dendron modified nano-liposomal contrast agent with magnetic resonance micro-imaging. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2018; 14:1315-1324. [PMID: 29626524 DOI: 10.1016/j.nano.2018.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 03/23/2018] [Accepted: 03/25/2018] [Indexed: 12/22/2022]
Abstract
The enhanced permeability and retention (EPR) effect is variable depending on nanoparticle properties and tumor/vessel conditions. Thus, intratumoral evaluations of the vasculature and nanoparticle distribution are important for predicting the therapeutic efficacy and the intractability of tumors. We aimed to develop a tumor vasculature evaluation method and high-resolution nanoparticle delivery imaging using magnetic resonance (MR) micro-imaging technology with a gadolinium (Gd)-dendron assembled liposomal contrast agent. Using the Gd-liposome and a cryogenic receiving coil, we achieved 50-μm isotropic MR angiography with clear visualization of tumor micro-vessel structure. The Gd-liposome-enhanced MR micro-imaging revealed differences in the vascular structures between Colon26- and SU-DHL6-grafted mice models. The vessel volumes and diameters measured for both tumors were significantly correlated with histological observations. The MR micro-imaging methods facilitate the evaluation of intratumoral vascularization patterns, the quantitative assessment of vascular-properties that alter tumor malignancy, particle retentivity, and the effects of treatment.
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Affiliation(s)
- Nobuhiro Nitta
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan; Group of Quantum-state Controlled MRI, QST, Chiba, Japan; Graduate School of Medicine, Tokushima University, Tokushima, Japan
| | - Yoichi Takakusagi
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan; Group of Quantum-state Controlled MRI, QST, Chiba, Japan
| | - Daisuke Kokuryo
- Graduate School of System Informatics, Kobe University, Kobe, Hyogo, Japan
| | - Sayaka Shibata
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan; Group of Quantum-state Controlled MRI, QST, Chiba, Japan
| | - Akihiro Tomita
- Department of Hematology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Tatsuya Higashi
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan
| | - Ichio Aoki
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan; Group of Quantum-state Controlled MRI, QST, Chiba, Japan.
| | - Masafumi Harada
- Graduate School of Medicine, Tokushima University, Tokushima, Japan
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Aarsvold S, Solano M, Garcia-Lopez J. Magnetic resonance imaging following regional limb perfusion of gadolinium contrast medium in 26 horses. Equine Vet J 2018; 50:649-657. [PMID: 29417635 DOI: 10.1111/evj.12818] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 12/13/2017] [Accepted: 01/26/2018] [Indexed: 01/27/2023]
Abstract
BACKGROUND Systemic administration of gadolinium contrast medium is common in small animals to increase lesion conspicuity and determine vascularisation of lesions identified with magnetic resonance imaging (MRI); however, the large volume required for systemic administration limits its use in horses. OBJECTIVES The purpose of this study was to assess the feasibility of administering a low dose of contrast medium via venous regional limb perfusion. STUDY DESIGN Prospective clinical study. METHODS Distal limbs of 26 horses (one limb per horse) were imaged with MRI before and after administration of 5 mL of gadopentetate dimeglumine (Magnevist® ) diluted with 5 mL of physiological saline via a palmar/plantar digital vein with a tourniquet in place at the level of the mid aspect of the third metacarpal/metatarsal bone. Commonly assessed structures of the equine distal limb were examined for normal and abnormal contrast enhancement. RESULTS Twenty-five of 26 horses had adequate contrast enhancement of their distal limb. The lack of adequate contrast enhancement in one limb was likely associated with failure of the tourniquet. No adverse reactions were identified in any horse. One hundred thirty-two lesions were detected, of which, 69 contrast enhanced. Twelve lesions were detected exclusively following contrast enhancement. MAIN LIMITATIONS Case numbers and lesion variability yielded insufficient data to perform statistical analyses. Histopathology was not performed on sound horses to determine if the imaged structures were normal. CONCLUSIONS Regional limb perfusion is a feasible method to administer gadolinium contrast material to the equine distal limb for MRI. The enhancement pattern of the equine distal limb in sound horses is described. Contrast enhanced MRI of the distal equine limb helps to further characterise lesions identified with precontrast images, including adhesions and deep digital flexor tendinopathy. Contrast enhanced MRI also aids in identification of additional lesions, such as neovascularisation.
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Affiliation(s)
- S Aarsvold
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts, USA
| | - M Solano
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts, USA
| | - J Garcia-Lopez
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts, USA
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The impact of injector-based contrast agent administration in time-resolved MRA. Eur Radiol 2017; 28:2246-2253. [PMID: 29218620 DOI: 10.1007/s00330-017-5178-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 10/28/2017] [Accepted: 11/06/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVES Time-resolved contrast-enhanced MR angiography (4D-MRA), which allows the simultaneous visualization of the vasculature and blood-flow dynamics, is widely used in clinical routine. In this study, the impact of two different contrast agent injection methods on 4D-MRA was examined in a controlled, standardized setting in an animal model. METHODS Six anesthetized Goettingen minipigs underwent two identical 4D-MRA examinations at 1.5 T in a single session. The contrast agent (0.1 mmol/kg body weight gadobutrol, followed by 20 ml saline) was injected using either manual injection or an automated injection system. A quantitative comparison of vascular signal enhancement and quantitative renal perfusion analyses were performed. RESULTS Analysis of signal enhancement revealed higher peak enhancements and shorter time to peak intervals for the automated injection. Significantly different bolus shapes were found: automated injection resulted in a compact first-pass bolus shape clearly separated from the recirculation while manual injection resulted in a disrupted first-pass bolus with two peaks. In the quantitative perfusion analyses, statistically significant differences in plasma flow values were found between the injection methods. CONCLUSIONS The results of both qualitative and quantitative 4D-MRA depend on the contrast agent injection method, with automated injection providing more defined bolus shapes and more standardized examination protocols. KEY POINTS • Automated and manual contrast agent injection result in different bolus shapes in 4D-MRA. • Manual injection results in an undefined and interrupted bolus with two peaks. • Automated injection provides more defined bolus shapes. • Automated injection can lead to more standardized examination protocols.
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Lim RP, Hornsey E, Ranatunga D, Hao H, Smith J, Spelman T, Chuen J, Goodwin M. Upper extremity non-contrast magnetic resonance venography (MRV) compared to contrast enhanced MRV and ultrasound. Clin Imaging 2017; 45:51-57. [PMID: 28601736 DOI: 10.1016/j.clinimag.2017.05.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/17/2017] [Accepted: 05/30/2017] [Indexed: 12/13/2022]
Abstract
PURPOSE To assess feasibility, image quality and measured venous caliber of non-contrast MRV (NC-MRV) of central and upper extremity veins, compared to contrast-enhanced MRV (CE-MRV) and ultrasound (US) in healthy volunteers. MATERIALS AND METHODS 10 subjects underwent NC-MRV and CE-MRV at 1.5 T, with comparison to US. Two radiologists evaluated MRI for image quality (IQ) and venous caliber. RESULTS AND CONCLUSIONS NC-MRV is feasible, with inferior IQ but comparable venous caliber measurements CE-MRV (mean 7.9±4.58 mm vs. 7.83±4.62, p=0.13). Slightly larger upper limb caliber measurements were derived for NC-MRV and CE-MRV compared to US (NC-MRV 5.2±1.8 mm, CE-MRV 4.9±1.6 mm, US 4.5±1.8 mm, both p<0.001).
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Affiliation(s)
- Ruth P Lim
- Department of Radiology, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia; Department of Radiology, The University of Melbourne, Parkville, Victoria 3052, Australia; Department of Surgery, The University of Melbourne, Parkville, Victoria 3052, Australia.
| | - Emma Hornsey
- Department of Radiology, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia
| | - Dinesh Ranatunga
- Department of Radiology, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia; Department of Radiology, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Huming Hao
- Department of Surgery, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia
| | - Julie Smith
- Department of Radiology, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia
| | - Tim Spelman
- Centre for Population Health, Burnet Institute, 85 Commercial Rd, Melbourne, Victoria 3004, Australia
| | - Jason Chuen
- Department of Surgery, The University of Melbourne, Parkville, Victoria 3052, Australia; Department of Surgery, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia
| | - Mark Goodwin
- Department of Radiology, Austin Health, PO Box 555, Heidelberg, Victoria 3084, Australia; Department of Radiology, The University of Melbourne, Parkville, Victoria 3052, Australia
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Comparison of Power Versus Manual Injection in Bolus Shape and Image Quality on Contrast-Enhanced Magnetic Resonance Angiography: An Experimental Study in a Swine Model. Invest Radiol 2017; 52:547-553. [PMID: 28448310 DOI: 10.1097/rli.0000000000000383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this study was to compare power versus manual injection in bolus shape and image quality on contrast-enhanced magnetic resonance angiography (CE-MRA). MATERIALS AND METHODS Three types of CE-MRA (head-neck 3-dimensional [3D] MRA with a test-bolus technique, thoracic-abdominal 3D MRA with a bolus-tracking technique, and thoracic-abdominal time-resolved 4-dimensional [4D] MRA) were performed after power and manual injection of gadobutrol (0.1 mmol/kg) at 2 mL/s in 12 pigs (6 sets of power and manual injections for each type of CE-MRA). For the quantitative analysis, the signal-to-noise ratio was measured on ascending aorta, descending aorta, brachiocephalic trunk, common carotid artery, and external carotid artery on the 6 sets of head-neck 3D MRA, and on ascending aorta, descending aorta, brachiocephalic trunk, abdominal aorta, celiac trunk, and renal artery on the 6 sets of thoracic-abdominal 3D MRA. Bolus shapes were evaluated on the 6 sets each of test-bolus scans and 4D MRA. For the qualitative analysis, arterial enhancement, superimposition of nontargeted enhancement, and overall image quality were evaluated on 3D MRA. Visibility of bolus transition was assessed on 4D MRA. Intraindividual comparison between power and manual injection was made by paired t test, Wilcoxon rank sum test, and analysis of variance by ranks. RESULTS Signal-to-noise ratio on 3D MRA was statistically higher with power injection than with manual injection (P < 0.001). Bolus shapes (test-bolus, 4D MRA) were represented by a characteristic standard bolus curve (sharp first-pass peak followed by a gentle recirculation peak) in all the 12 scans with power injection, but only in 1 of the 12 scans with manual injection. Standard deviations of time-to-peak enhancement were smaller in power injection than in manual injection. Qualitatively, although both injection methods achieved diagnostic quality on 3D MRA, power injection exhibited significantly higher image quality than manual injection (P = 0.001) due to significantly higher arterial enhancement (P = 0.031) and less superimposition of nontargeted enhancement (P = 0.001). Visibility of bolus transition on 4D MRA was significantly better with power injection than with manual injection (P = 0.031). CONCLUSIONS Compared with manual injection, power injection provides more standardized bolus shapes and higher image quality due to higher arterial enhancement and less superimposition of nontargeted vessels.
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Jost G, Endrikat J, Pietsch H. The Impact of Injector-Based Contrast Agent Administration on Bolus Shape and Magnetic Resonance Angiography Image Quality. MAGNETIC RESONANCE INSIGHTS 2017; 10:1178623X17705894. [PMID: 28579796 PMCID: PMC5428122 DOI: 10.1177/1178623x17705894] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 01/25/2017] [Indexed: 11/23/2022]
Abstract
Objective: To compare injector-based contrast agent (CA) administration with hand injection in magnetic resonance angiography (MRA). Methods: Gadobutrol was administered in 6 minipigs with 3 protocols: (a) hand injection (one senior technician), (b) hand injection (6 less-experienced technicians), and (c) power injector administration. The arterial bolus shape was quantified by test bolus measurements. A head and neck MRA was performed for quantitative and qualitative comparison of signal enhancement. Results: A significantly shorter time to peak was observed for protocol C, whereas no significant differences between protocols were found for peak height and bolus width. However, for protocol C, these parameters showed a much lower variation. The MRA revealed a significantly higher signal-to-noise ratio for injector-based administration. A superimposed strong contrast of the jugular vein was found in 50% of the hand injections. Conclusions: Injector-based CA administration results in a more standardized bolus shape, a higher vascular contrast, and a more robust visualization of target vessels.
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Affiliation(s)
- Gregor Jost
- MR and CT Contrast Media Research, Bayer AG, Berlin, Germany
| | - Jan Endrikat
- Global Medical & Clinical Affairs Radiology, Bayer AG, Berlin, Germany.,Department of Gynecology, Obstetrics and Reproductive Medicine, University Medical School of Saarland, Homburg, Germany
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Clark TJ, Wilson GJ, Maki JH. Effect of injection rate on contrast-enhanced MR angiography image quality: Modulation transfer function analysis. Magn Reson Med 2016; 78:357-369. [DOI: 10.1002/mrm.26349] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 06/29/2016] [Accepted: 06/29/2016] [Indexed: 12/20/2022]
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Evaluation of a tailored injection profile (TIP) algorithm for uniform contrast-enhanced signal intensity profiles in MR angiography. J Magn Reson Imaging 2016; 44:1664-1672. [DOI: 10.1002/jmri.25298] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/19/2016] [Indexed: 01/17/2023] Open
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Mueller GC, Lu JC, Mahani MG, Dorfman AL, Agarwal PP. MR Imaging of Thoracic Veins. Magn Reson Imaging Clin N Am 2016; 23:293-307. [PMID: 25952521 DOI: 10.1016/j.mric.2015.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
MR imaging of thoracic veins is performed to evaluate the heart and thoracic vasculature. The protocol can be customized to the clinical question. In the embryo, systemic and pulmonary vein development is closely related to heart development. Congenital anomalies of the thoracic veins are strongly associated with other cardiac and situs abnormalities. Acquired venous abnormalities are often iatrogenic, or secondary to malignancy. This article discusses development and anatomy of the thoracic venous systems, clinical MR imaging methods for their evaluation, and illustrates the MR imaging appearance of congenital and acquired abnormalities of systemic thoracic veins, coronary sinus, and pulmonary veins.
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Affiliation(s)
- Gisela C Mueller
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109-2713, USA.
| | - Jimmy C Lu
- Department of Pediatrics, University of Michigan Congenital Heart Center, C.S. Mott Children's Hospital, University of Michigan, 1540 East Hospital Drive, Ann Arbor, MI 48109-4204, USA; Department of Radiology, University of Michigan Congenital Heart Center, C.S. Mott Children's Hospital, University of Michigan, 1540 East Hospital Drive, Ann Arbor, MI 48109-4204, USA
| | - Maryam Ghadimi Mahani
- Department of Radiology, C.S. Mott Children's Hospital, University of Michigan, Floor 3 Recp A Room 3660A, 1540 East Hospital Drive SPC 4252, Ann Arbor, MI 48109, USA
| | - Adam L Dorfman
- Department of Pediatrics, University of Michigan Congenital Heart Center, C.S. Mott Children's Hospital, University of Michigan, 1540 East Hospital Drive, Ann Arbor, MI 48109-4204, USA; Department of Radiology, University of Michigan Congenital Heart Center, C.S. Mott Children's Hospital, University of Michigan, 1540 East Hospital Drive, Ann Arbor, MI 48109-4204, USA
| | - Prachi P Agarwal
- Department of Radiology, Cardiovascular Center, University of Michigan, Floor 5 Room 5383, 1500 East Medical Center Drive SPC 5868, Ann Arbor, MI 48109, USA
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Weavers PT, Borisch EA, Johnson CP, Riederer SJ. Acceleration apportionment: a method of improved 2D SENSE acceleration applied to 3D contrast-enhanced MR angiography. Magn Reson Med 2015; 71:672-80. [PMID: 23450817 DOI: 10.1002/mrm.24700] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE In 2D SENSE-accelerated 3D Cartesian acquisition, the net acceleration factor R is the product of the two individual accelerations, R = RY × RZ. Acceleration Apportionment tailors acceleration parameters (RY, RZ) to improve parallel imaging performance on a patient- and coil-specific basis and is demonstrated in contrast-enhanced MR angiography. METHODS A performance metric is defined based on coil sensitivity information which identifies the (RY, RZ) pair that optimally trades off image quality with scan time reduction on a patient-specific basis. Acceleration Apportionment is evaluated using retrospective analysis of contrast-enhanced MR angiography studies, and prospective studies in which optimally apportioned parameters are compared with standard acceleration parameters. RESULTS The retrospective studies show strong variability in optimal acceleration parameters between anatomic regions and between patients. Prospective application of apportionment to foot contrast-enhanced MR angiography with an 8-channel receiver array provides a 20% increase in net acceleration with improved contrast-to-noise ratio. Application to 16-channel contrast-enhanced MR angiography of the feet and calves suggests 10% acceleration increase to R > 13 and no contrast-to-noise ratio loss. The specific implementation allows the optimum (RY, RZ) pair to be determined within one minute. CONCLUSION Optimum 2D SENSE acceleration parameters can be automatically chosen on a per-exam basis to allow improved performance without disrupting the clinical workflow.
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Wang K, Beatty PJ, Nagle SK, Reeder SB, Holmes JH, Rahimi MS, Bell LC, Korosec FR, Brittain JH. Application of direct virtual coil to dynamic contrast-enhanced MRI and MR angiography with data-driven parallel imaging. Magn Reson Med 2015; 71:783-9. [PMID: 23441013 DOI: 10.1002/mrm.24686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE To demonstrate the feasibility of direct virtual coil (DVC) in the setting of 4D dynamic imaging used in multiple clinical applications. THEORY AND METHODS Three dynamic imaging applications were chosen: pulmonary perfusion, liver perfusion, and peripheral MR angiography (MRA), with 18, 11, and 10 subjects, respectively. After view-sharing, the k-space data were reconstructed twice: once with channel-by-channel (CBC) followed by sum-of-squares coil combination and once with DVC. Images reconstructed using CBC and DVC were compared and scored based on overall image quality by two experienced radiologists using a five-point scale. RESULTS The CBC and DVC showed similar image quality in image domain. Time course measurements also showed good agreement in the temporal domain. CBC and DVC images were scored as equivalent for all pulmonary perfusion cases, all liver perfusion cases, and four of the 10 peripheral MRA cases. For the remaining six peripheral MRA cases, DVC were scored as slightly better (not clinically significant) than the CBC images by Radiologist A and as equivalent by Radiologist B. CONCLUSION For dynamic contrast-enhanced MR applications, it is clinically feasible to reduce image reconstruction time while maintaining image quality and time course measurement using the DVC technique.
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Affiliation(s)
- Kang Wang
- Global Applied Science Laboratory, GE Healthcare, Madison, Wisconsin, USA
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Keith L, Rahimi M, Holmes J, Brittain J, Korosec F. Use of a computer-controlled motion phantom to investigate the temporal and spatial fidelity of HYPR processing. Magn Reson Med 2015; 71:702-10. [PMID: 23475821 DOI: 10.1002/mrm.24707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
PURPOSE In this work, we investigate the spatial and temporal fidelity of highly constrained backPRojection (HYPR) processing using a computer-controlled motion phantom. The goal of this experimental set-up was to provide not only well-defined temporal dynamics and spatial characteristics of the motion phantom, but also circumstances that imitate in vivo scenarios. METHODS The phantom was designed to represent an artery flanked on both sides by vein. Both arterial and venous components have different temporal dynamics but are confluent, which corresponds to a difficult scenario for HYPR. Spatial and temporal fidelity was investigated by measuring signal intensity profiles through the phantom both orthogonal to as well as along the direction of motion. RESULTS Spatial fidelity profiles measured from the HYPR processed images yielded full-width-at-half-maximum values very similar to those measured in non-HYPR-processed images. Furthermore, there was no significant spreading of the motion phantom leading edge in HYPR processed images. CONCLUSION Although HYPR processing has certain characteristic artifacts that are discussed, the technique can be used to improve image quality of highly undersampled time frame images with minimal loss of spatial or temporal fidelity.
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Affiliation(s)
- Lauren Keith
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA
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Zhou Z, Wu C, Liu H, Zhu X, Zhao Z, Wang L, Xu Y, Ai H, Gao J. Surface and interfacial engineering of iron oxide nanoplates for highly efficient magnetic resonance angiography. ACS NANO 2015; 9:3012-22. [PMID: 25670480 DOI: 10.1021/nn507193f] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Magnetic resonance angiography using gadolinium-based molecular contrast agents suffers from short diagnostic window, relatively low resolution and risk of toxicity. Taking into account the chemical exchange between metal centers and surrounding protons, magnetic nanoparticles with suitable surface and interfacial features may serve as alternative T1 contrast agents. Herein, we report the engineering on surface structure of iron oxide nanoplates to boost T1 contrast ability through synergistic effects between exposed metal-rich Fe3O4(100) facets and embedded Gd2O3 clusters. The nanoplates show prominent T1 contrast in a wide range of magnetic fields with an ultrahigh r1 value up to 61.5 mM(-1) s(-1). Moreover, engineering on nanobio interface through zwitterionic molecules adjusts the in vivo behaviors of nanoplates for highly efficient magnetic resonance angiography with steady-state acquisition window, superhigh resolution in vascular details, and low toxicity. This study provides a powerful tool for sophisticated design of MRI contrast agents for diverse use in bioimaging applications.
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Affiliation(s)
- Zijian Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, The Key Laboratory for Chemical Biology of Fujian Province, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Changqiang Wu
- National Engineering Research Center for Biomaterials, and Department of Radiology, West China Hospital, Sichuan University, Chengdu 610064, China
| | - Hanyu Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, The Key Laboratory for Chemical Biology of Fujian Province, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xianglong Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, The Key Laboratory for Chemical Biology of Fujian Province, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Zhenghuan Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, The Key Laboratory for Chemical Biology of Fujian Province, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Lirong Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, The Key Laboratory for Chemical Biology of Fujian Province, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Ye Xu
- National Engineering Research Center for Biomaterials, and Department of Radiology, West China Hospital, Sichuan University, Chengdu 610064, China
| | - Hua Ai
- National Engineering Research Center for Biomaterials, and Department of Radiology, West China Hospital, Sichuan University, Chengdu 610064, China
| | - Jinhao Gao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, The Key Laboratory for Chemical Biology of Fujian Province, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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Abstract
Magnetic resonance (MR) angiography of the pulmonary arteries is a rapidly evolving technique with proven clinical usefulness. Multiple-step protocols, such as MR perfusion followed by high-spatial resolution MR angiography, seem to be a good approach for the assessment of different vascular diseases affecting the pulmonary arteries. In combination with other imaging sequences, MR imaging is one of the most comprehensive potential noninvasive imaging techniques available.
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Affiliation(s)
- Sebastian Ley
- Diagnostic and Interventional Radiology, Chirurgische Klinik Dr Rinecker, Am Isarkanal 30, Munich 81379, Germany; Department of Clinical Radiology, Ludwig Maximilians University, Marchioninistrasse 15, Munich 81377, Germany.
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Cheong BYC, Angelini P. Magnetic Resonance Imaging of the Myocardium, Coronary Arteries, and Anomalous Origin of Coronary Arteries. Coron Artery Dis 2015. [DOI: 10.1007/978-1-4471-2828-1_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Stalder AF, Schmidt M, Quick HH, Schlamann M, Maderwald S, Schmitt P, Wang Q, Nadar MS, Zenge MO. Highly undersampled contrast-enhanced MRA with iterative reconstruction: Integration in a clinical setting. Magn Reson Med 2014; 74:1652-60. [PMID: 25522299 DOI: 10.1002/mrm.25565] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/17/2014] [Accepted: 11/17/2014] [Indexed: 11/06/2022]
Abstract
PURPOSE To integrate, optimize, and evaluate a three-dimensional (3D) contrast-enhanced sparse MRA technique with iterative reconstruction on a standard clinical MR system. METHODS Data were acquired using a highly undersampled Cartesian spiral phyllotaxis sampling pattern and reconstructed directly on the MR system with an iterative SENSE technique. Undersampling, regularization, and number of iterations of the reconstruction were optimized and validated based on phantom experiments and patient data. Sparse MRA of the whole head (field of view: 265 × 232 × 179 mm(3) ) was investigated in 10 patient examinations. RESULTS High-quality images with 30-fold undersampling, resulting in 0.7 mm isotropic resolution within 10 s acquisition, were obtained. After optimization of the regularization factor and of the number of iterations of the reconstruction, it was possible to reconstruct images with excellent quality within six minutes per 3D volume. Initial results of sparse contrast-enhanced MRA (CEMRA) in 10 patients demonstrated high-quality whole-head first-pass MRA for both the arterial and venous contrast phases. CONCLUSION While sparse MRI techniques have not yet reached clinical routine, this study demonstrates the technical feasibility of high-quality sparse CEMRA of the whole head in a clinical setting. Sparse CEMRA has the potential to become a viable alternative where conventional CEMRA is too slow or does not provide sufficient spatial resolution.
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Affiliation(s)
| | | | - Harald H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Germany
| | - Marc Schlamann
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Germany
| | - Stefan Maderwald
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Germany
| | | | - Qiu Wang
- Siemens Corporate Technology, Princeton, New Jersey, USA
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Wurz C, Davari A, Ackermann H, Vogl TJ. Diagnostic performance of CE-MRA in grading stenosis and therapy planning with TASC II classification. Vascular 2014; 23:403-10. [PMID: 25298134 DOI: 10.1177/1708538114552094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objectives To assess to what extent results of CE-MRA coincide with DSA in grading of stenosis and planning of therapy in patients with PAOD. Materials and methods Retrospectively, images of 71 PAOD-patients were studied by three observers. For evaluation, the lower limb was subdivided into 31 segments and categorized with TASCII-score. Results In grading stenosis, both modalities agreed in 93.26%. CE-MRA achieved sensitivity of 92.69% and specificity of 96.87% (κ = 0.88). The concordance of TASCII-classification was almost perfect. Conclusion CE-MRA is an excellent method for the evaluation of PAOD with some tendency to overrate the grade of stenosis.
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Affiliation(s)
- Clemens Wurz
- Institut für Diagnostische und Interventionelle Radiologie, Klinikum der Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, Germany
| | - Amir Davari
- Institut für Diagnostische und Interventionelle Radiologie, Klinikum der Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, Germany
| | - Hanns Ackermann
- Institut für Biostatistik und Mathematische Modellierung, Klinikum der Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, Germany
| | - Thomas J Vogl
- Institut für Diagnostische und Interventionelle Radiologie, Klinikum der Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, Germany
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Bultman EM, Klaers J, Johnson KM, François CJ, Schiebler ML, Reeder SB, Block WF. Non-contrast enhanced 3D SSFP MRA of the renal allograft vasculature: a comparison between radial linear combination and Cartesian inflow-weighted acquisitions. Magn Reson Imaging 2013; 32:190-5. [PMID: 24246390 DOI: 10.1016/j.mri.2013.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 09/03/2013] [Accepted: 10/07/2013] [Indexed: 11/20/2022]
Abstract
Renal transplant patients often require imaging to ensure appropriate graft placement, to assess integrity of transplant vessel anastomosis and to evaluate for stenosis that can be a cause of graft failure. Because there is risk for nephrogenic systemic fibrosis in the setting of renal insufficiency, the use of non-contrast MRA in these patients is helpful. In this study, the ability of two non-contrast MRA methods - 3D radial linear combination balanced SSFP (VIPR-SSFP) and inflow-weighted Cartesian SSFP (IFIR) - to visualize the transplant renal vessels is compared. Twenty-one renal transplant patients were scanned using the VIPR-SSFP and IFIR sequences. Diagnostic efficacy of the sequences was scored using a four point Likert scale according to the following criteria: overall image quality, fat suppression, and arterial/venous visualization quality. Average scores for each criterion were compared using the Wilcoxon signed-rank test. In addition to significantly improved venous visualization, the VIPR-SSFP sequence provided significantly improved fat suppression quality (p<0.03) compared to IFIR. VIPR-SSFP also identified several pathologies such as renal arterial pseudoaneurysm that were not visible on the IFIR images. However, IFIR afforded superior quality of arterial visualization (p<0.005). These two methods of non-contrast MR imaging each have significant strengths and are complementary to each other in evaluating the vasculature of renal allografts.
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Affiliation(s)
- Eric M Bultman
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI.
| | - Jessica Klaers
- Department of Medical Physics, University of Wisconsin, Madison, WI
| | - Kevin M Johnson
- Department of Medical Physics, University of Wisconsin, Madison, WI
| | | | | | - Scott B Reeder
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI; Department of Medical Physics, University of Wisconsin, Madison, WI; Department of Radiology, University of Wisconsin, Madison, WI; Department of Medicine, University of Wisconsin, Madison, WI
| | - Walter F Block
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI; Department of Medical Physics, University of Wisconsin, Madison, WI; Department of Radiology, University of Wisconsin, Madison, WI
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Young PM, Mostardi PM, Glockner JF, Vrtiska TR, Macedo T, Haider CR, Riederer SJ. Prospective comparison of cartesian acquisition with projection-like reconstruction magnetic resonance angiography with computed tomography angiography for evaluation of below-the-knee runoff. J Vasc Interv Radiol 2013; 24:392-9. [PMID: 23433414 PMCID: PMC3593305 DOI: 10.1016/j.jvir.2012.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 11/05/2012] [Accepted: 11/08/2012] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To compare prospectively the assessment of stenosis and radiologist confidence in the evaluation of below-the-knee lower extremity runoff vessels between computed tomography (CT) angiography and contrast-enhanced magnetic resonance (MR) angiography in a cohort of 19 clinical patients. MATERIALS AND METHODS The study was compliant with the Health Insurance Portability and Accountability Act of 1996 and approved by the institutional review board. Imaging was performed in 19 consecutive patients with known or suspected peripheral arterial disease; both CT angiography and a more recently developed MR angiography technique were performed within 24 hours of each other and before any therapeutic intervention. Resulting images were randomized and interpreted in blinded fashion by four board-certified radiologists with expertise in CT angiography and MR angiography. Vasculature of the lower leg was apportioned into 22 segments, 11 for each leg. For each segment, degree of stenosis and confidence of diagnosis were determined using a 3-point scale. Differences between CT angiography and MR angiography were assessed for significance using pooled histograms that were analyzed using the Wilcoxon signed rank test. RESULTS For assessment of stenosis, there was no difference in CT angiography compared with MR angiography for 20 of 22 segments. For confidence of diagnosis, assessment of popliteal arteries was superior on CT angiography compared with MR angiography (P<.05). Confidence in assessment of both tibioperoneal trunks and the left proximal anterior tibial artery was not significantly different between CT angiography and MR angiography. Confidence in assessment of all other 17 segments was superior with MR angiography compared with CT angiography (P<.02). CONCLUSIONS MR angiography using the method described here is a promising technique for evaluating lower extremity arterial runoff. MR angiography had an overall superior performance in radiologist confidence compared with CT angiography for imaging runoff vessels below the knee.
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Affiliation(s)
- Phillip M Young
- Department of Radiology, Mayo Clinic, Mayo 2, 200 First Street SW, Rochester, MN 55905, USA.
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Priest AN, Joubert I, Winterbottom AP, See TC, Graves MJ, Lomas DJ. Initial clinical evaluation of a non-contrast-enhanced MR angiography method in the distal lower extremities. Magn Reson Med 2013; 70:1644-52. [DOI: 10.1002/mrm.24626] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 11/29/2012] [Accepted: 12/13/2012] [Indexed: 12/20/2022]
Affiliation(s)
| | - Ilse Joubert
- Department of Radiology; Addenbrooke's Hospital; Cambridge UK
| | | | - Teik Choon See
- Department of Radiology; Addenbrooke's Hospital; Cambridge UK
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Gitsioudis G, Stuber M, Arend I, Thomas M, Yu J, Hilbel T, Giannitsis E, Katus HA, Korosoglou G. Steady-state equilibrium phase inversion recovery ON-resonant water suppression (IRON) MR angiography in conjunction with superparamagnetic nanoparticles. A robust technique for imaging within a wide range of contrast agent dosages. J Magn Reson Imaging 2013; 38:836-44. [PMID: 23418107 DOI: 10.1002/jmri.24043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 12/13/2012] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate the ability of inversion recovery ON-resonant water suppression (IRON) in conjunction with P904 (superparamagnetic nanoparticles which consisting of a maghemite core coated with a low-molecular-weight amino-alcohol derivative of glucose) to perform steady-state equilibrium phase MR angiography (MRA) over a wide dose range. MATERIALS AND METHODS Experiments were approved by the institutional animal care committee. Rabbits (n = 12) were imaged at baseline and serially after the administration of 10 incremental dosages of 0.57-5.7 mgFe/Kg P904. Conventional T1-weighted and IRON MRA were obtained on a clinical 1.5 Tesla (T) scanner to image the thoracic and abdominal aorta, and peripheral vessels. Contrast-to-noise ratios (CNR) and vessel sharpness were quantified. RESULTS Using IRON MRA, CNR and vessel sharpness progressively increased with incremental dosages of the contrast agent P904, exhibiting constantly higher contrast values than T1 -weighted MRA over a very wide range of contrast agent doses (CNR of 18.8 ± 5.6 for IRON versus 11.1 ± 2.8 for T1 -weighted MRA at 1.71 mgFe/kg, P = 0.02 and 19.8 ± 5.9 for IRON versus -0.8 ± 1.4 for T1-weighted MRA at 3.99 mgFe/kg, P = 0.0002). Similar results were obtained for vessel sharpness in peripheral vessels, (Vessel sharpness of 46.76 ± 6.48% for IRON versus 33.20 ± 3.53% for T1-weighted MRA at 1.71 mgFe/Kg, P = 0.002, and of 48.66 ± 5.50% for IRON versus 19.00 ± 7.41% for T1-weighted MRA at 3.99 mgFe/Kg, P = 0.003). CONCLUSION Our study suggests that quantitative CNR and vessel sharpness after the injection of P904 are consistently higher for IRON MRA when compared with conventional T1-weighted MRA. These findings apply for a wide range of contrast agent dosages.
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Wright KL, Seiberlich N, Jesberger JA, Nakamoto DA, Muzic RF, Griswold MA, Gulani V. Simultaneous magnetic resonance angiography and perfusion (MRAP) measurement: initial application in lower extremity skeletal muscle. J Magn Reson Imaging 2013; 38:1237-44. [PMID: 23389970 DOI: 10.1002/jmri.24020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 12/07/2012] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To obtain a simultaneous 3D magnetic resonance angiography and perfusion (MRAP) using a single acquisition and to demonstrate MRAP in the lower extremities. A time-resolved contrast-enhanced exam was used in MRAP to simultaneously acquire a contrast-enhanced MR angiography (MRA) and dynamic contrast-enhanced (DCE) perfusion, which currently requires separate acquisitions and thus two contrast doses. MRAP can be used to assess large and small vessels in vascular pathologies such as peripheral arterial disease. MATERIALS AND METHODS MRAP was performed on 10 volunteers following unilateral plantar flexion exercise (one leg exercised and one rested) on two separate days. Data were acquired after administration of a single dose of contrast agent using an optimized sampling strategy, parallel imaging, and partial-Fourier acquisition to obtain a high spatial resolution, 3D-MRAP frame every 4 seconds. Two radiologists assessed MRAs for image quality, a signal-to-noise ratio (SNR) analysis was performed, and pharmacokinetic modeling yielded perfusion (K(trans) ). RESULTS MRA images had high SNR and radiologist-assessed diagnostic quality. Mean K(trans) ± standard error were 0.136 ± 0.009, 0.146 ± 0.012, and 0.191 ± 0.012 min(-1) in the resting tibialis anterior, gastrocnemius, and soleus, respectively, which significantly increased with exercise to 0.291 ± 0.018, 0.270 ± 0.019, and 0.338 ± 0.022 min(-1) . Bland-Altman analysis showed good repeatability. CONCLUSION MRAP provides simultaneous high-resolution MRA and quantitative DCE exams to assess large and small vessels with a single contrast dose. Application in skeletal muscle shows quantitative, repeatable perfusion measurements, and the ability to measure physiological differences.
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Affiliation(s)
- Katherine L Wright
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA; Case Center for Imaging Research, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, Ohio, USA
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Wang J, Yan F, Liu J, Lu J, Li D, Luan J, Wang X, Li Y, Iezzi R, De Cobelli F. Multicenter, intra-individual comparison of single dose gadobenate dimeglumine and double dose gadopentetate dimeglumine for MR angiography of the peripheral arteries (the Peripheral VALUE Study). J Magn Reson Imaging 2013; 38:926-37. [PMID: 23371919 DOI: 10.1002/jmri.24040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/13/2012] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To prospectively compare single dose gadobenate dimeglumine with double dose gadopentetate dimeglumine for CE-MRA in patients with peripheral arterial occlusive disease (PAOD) using an intra-individual crossover study design in which all patients received both contrast agents in otherwise identical CE-MRA examinations. MATERIALS AND METHODS Institutional review board and regulatory approval were granted and all patients provided written informed consent. Sixty-eight patients (53M/15F; 62.4 ± 15.7 years) with mild-to-severe PAOD were enrolled for randomized 3-station CE-MRA with 0.1 mmol/kg gadobenate dimeglumine and 0.2 mmol/kg gadopentetate dimeglumine. Three blinded readers assessed images for vessel anatomical delineation, disease detection/exclusion, and global preference. Diagnostic performance for detection of ≥51% stenosis was determined for 53 patients who underwent DSA. Noninferiority was assessed using the Wilcoxon Signed Rank, McNemar, and Wald tests. Quantitative enhancement was compared. RESULTS No differences (P ≥ 0.25) were noted for any qualitative parameter at any station. Equivalence was reported in at least 62/64 patients (93.8% 3-reader agreement) for diagnostic preference. Superiority for gadobenate dimeglumine was reported by all readers for diagnostic performance (sensitivity: 80.4-88.0% versus 75.2-85.8%; specificity: 89.8-96.0% versus 88.7-94.8%; accuracy: 87.4-91.7% versus 84.9-90.6%; PPV: 84.0-92.8% versus 82.3-90.8%; NPV: 88.5-92.4% versus 85.7-91.1%). Quantitative enhancement was similar in the pelvis but significantly (P < 0.05) greater with gadobenate dimeglumine in the thigh for two readers. CONCLUSION Image quality and diagnostic performance on peripheral CE-MRA with 0.1 mmol/kg gadobenate dimeglumine is at least equivalent to that with 0.2 mmol/kg gadopentetate dimeglumine.
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Affiliation(s)
- Jian Wang
- Radiology Department, Shanghai Changhai Hospital, Shanghai, China
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Merkx MAG, Bescós JO, Geerts L, Bosboom EMH, van de Vosse FN, Breeuwer M. Accuracy and precision of vessel area assessment: manual versus automatic lumen delineation based on full-width at half-maximum. J Magn Reson Imaging 2012; 36:1186-93. [PMID: 22826150 DOI: 10.1002/jmri.23752] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 06/08/2012] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To evaluate the accuracy and precision of manual and automatic blood vessel diameter measurements, a quantitative comparison was conducted, using both phantom and clinical 3D magnetic resonance angiography (MRA) data. Since diameters are often manually measured, which likely is influenced by operator dependency, automatic lumen delineation, based on the full-width at half-maximum (FWHM), could improve these measurements. MATERIALS AND METHODS Manual and automatic diameter assessments were compared, using MRA data from a vascular phantom (geometry obtained with μCT) and clinical MRA data. The diameters were manually assessed by 15 MRA experts, using both caliper and contour tools. To translate the experimental results to clinical practice, the precision obtained using phantom data was compared to the precision obtained with clinical data. RESULTS A diameter error <10% was obtained with resolutions above 2, 3, and 5 pixels/diameter for the automatic FWHM, contour, and caliper methods, respectively. Using phantom data, precision of the manual methods was low (error >20%), even at high resolutions, while precision for the automatic method was high (error <3%) when using more than 2 pixels/diameter. A similar trend was found with clinical data. CONCLUSION The results obtained clearly demonstrate improvement in the accuracy and precision of vessel diameter measurements with use of the automatic FWHM-based method.
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Affiliation(s)
- Maarten A G Merkx
- Maastricht University Medical Center, Department of Biomedical Engineering, Maastricht, The Netherlands.
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Mostardi PM, Young PM, McKusick MA, Riederer SJ. High temporal and spatial resolution imaging of peripheral vascular malformations. J Magn Reson Imaging 2012; 36:933-42. [PMID: 22674646 DOI: 10.1002/jmri.23714] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 04/30/2012] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To assess the performance of a recently developed 3D time-resolved CE-MRA technique, Cartesian Acquisition with Projection-Reconstruction-like sampling (CAPR), for accurate characterization and treatment planning of vascular malformations of the periphery. MATERIALS AND METHODS Twelve patient studies were performed (eight female, four male; average age, 33 years). The protocol consisted of three-dimensional (3D) time-resolved CE-MRA followed by a single late phase T1-weighted acquisition. Vascular malformations were imaged in the forearm, hand, thigh, and foot. Imaging evaluation was performed for accurate characterization of lesion type, identification of feeding and draining vessels, involvement with surrounding tissue, overall quality for diagnosis and treatment planning, and correlation with conventional angiography. RESULTS Time-resolved CE-MRA allowed for characterization of malformation flow and type. Feeding and draining vessels were identified in all cases. Overall quality for diagnosis and treatment planning was 3.58/4.0, and correlation with conventional angiography was scored as 3.89/4.0. CONCLUSION The CAPR time series has been shown to portray the temporal dynamics and structure of vascular malformations as well as the normal vasculature with high quality. CAPR time-resolved imaging is able to accurately characterize high and low flow lesions, allowing for pretreatment lesion assessment and treatment planning. Delayed imaging is important to capture complete filling of very slow flow vascular malformations.
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Faggioni L, Zampa V, Ortori S, Picano E, De Lucia R, Soldati E, Bongiorni MG, Neri E, Bartolozzi C. Time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium–pulmonary veins complex with half dose of intravenous gadolinium-based contrast agent. Technical feasibility and comparison with a conventional CEMRA, full contrast dose protocol. Eur J Radiol 2012; 81:250-6. [DOI: 10.1016/j.ejrad.2010.12.096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 12/28/2010] [Indexed: 11/30/2022]
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The Role of 3 Tesla MRA in the Detection of Intracranial Aneurysms. Int J Vasc Med 2012; 2012:792834. [PMID: 22292121 PMCID: PMC3265088 DOI: 10.1155/2012/792834] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Accepted: 10/09/2011] [Indexed: 12/01/2022] Open
Abstract
Intracranial aneurysms constitute a common pathological entity, affecting approximately 1–8% of the general population. Their early detection is essential for their prompt treatment. Digital subtraction angiography is considered the imaging method of choice. However, other noninvasive methodologies such as CTA and MRA have been employed in the investigation of patients with suspected aneurysms. MRA is a noninvasive angiographic modality requiring no radiation exposure. However, its sensitivity and diagnostic accuracy were initially inadequate. Several MRA techniques have been developed for overcoming all these drawbacks and for improving its sensitivity. 3D TOF MRA and contrast-enhanced MRA are the most commonly employed techniques. The introduction of 3 T magnetic field further increased MRA's sensitivity, allowing detection of aneurysms smaller than 3 mm. The development of newer MRA techniques may provide valuable information regarding the flow characteristics of an aneurysm. Meticulous knowledge of MRA's limitations and pitfalls is of paramount importance for avoiding any erroneous interpretation of its findings.
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Double Bolus Application in TWIST-MR-Angiography of the Cervical Arteries. Radiol Res Pract 2012; 2012:203538. [PMID: 23125928 PMCID: PMC3483778 DOI: 10.1155/2012/203538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/02/2012] [Accepted: 10/02/2012] [Indexed: 12/02/2022] Open
Abstract
Purpose.
The aim of the present work was to test the feasibility of the time-resolved MR-angiography (TWIST-MRA) of cervical arteries using double bolus injection. Material and Methods. TWIST-MRA with a temporal resolution of 8.4 seconds for each frame and a spatial resolution with a voxel size of 0.61 × 0.58 × 0.8 mm3
was performed in 24 patients. A biphasic bolus injection protocol was used with the second injection being started 21 seconds after the first contrast dye bolus. Diagnostic image quality was rated according to a 4-point scale. Results. In 12 patients (50%) no clear separation between the cervical venous and arterial vessels was evident after the first bolus injection. Using TWIST-MRA data acquired after the second bolus a sufficient diagnostic image quality (rating ≥3, mean 3.5) could be obtained in 22 of 24 patients (92%). Discussion. The double bolus injection protocol using TWIST-MRA allows for very good separation of the cervical arteries.
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Lee D, Heo SH, Kim EJ, Chang DI. Pseudo-occlusion of the extracranial carotid artery caused by intracranial carotid artery stenosis. Neurol Sci 2011; 33:1201-3. [PMID: 22134755 DOI: 10.1007/s10072-011-0870-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 11/18/2011] [Indexed: 11/29/2022]
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Takei N, Miyoshi M, Kabasawa H. Noncontrast MR angiography for supraaortic arteries using inflow enhanced inversion recovery fast spin echo imaging. J Magn Reson Imaging 2011; 35:957-62. [DOI: 10.1002/jmri.23515] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 10/26/2011] [Indexed: 11/09/2022] Open
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