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Cardiovascular Magnetic Resonance Imaging for the Biomedical Engineer. Cardiovasc Eng Technol 2011. [DOI: 10.1007/s13239-011-0066-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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52
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Priest AN, Graves MJ, Lomas DJ. Non-contrast-enhanced vascular magnetic resonance imaging using flow-dependent preparation with subtraction. Magn Reson Med 2011; 67:628-37. [DOI: 10.1002/mrm.23040] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 04/19/2011] [Accepted: 05/18/2011] [Indexed: 01/09/2023]
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53
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Lefrançois W, Thiaudière E, Ben Hassen W, Sanchez S, Franconi JM, Miraux S. Fast whole-body magnetic resonance angiography in mice. Magn Reson Med 2011; 66:32-9. [DOI: 10.1002/mrm.22985] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/08/2011] [Accepted: 04/08/2011] [Indexed: 11/08/2022]
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Haney CR, Pelizzari CA, Foxley S, Zamora MA, Mustafi D, Tretiakova M, Li S, Fan X, Karczmar GS. HiSStology: high spectral and spatial resolution magnetic resonance imaging detection of vasculature validated by histology and micro-computed tomography. Mol Imaging 2011; 10:187-96. [PMID: 21443840 DOI: 10.2310/7290.2010.00033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 03/31/2010] [Indexed: 11/18/2022] Open
Abstract
High spectral and spatial resolution (HiSS) data, acquired with echo-planar spectroscopic imaging (EPSI), can be used to acquire water spectra from each small image voxel. These images are sensitive to changes in local susceptibility caused by superparamagnetic iron oxide particles (SPIO); therefore, we hypothesized that images derived from HiSS data are very sensitive to tumor neovasculature following injection of SPIO. Accurate image registration was used to validate HiSS detection of neovasculature with histology and micro-computed tomographic (microCT) angiography. Athymic nude mice and Copenhagen rats were inoculated with Dunning AT6.1 prostate tumor cells in the right hind limb. The tumor region was imaged pre- and post-intravenous injection of SPIO. Three-dimensional assemblies of the CD31-stained histologic slices of the mouse legs and the microCT images of the rat vascular casts were registered with EPSI. The average distance between HiSS-predicted regions of high vascular density on magnetic resonance imaging and CD31-stained regions on histology was 200 μm. Similarly, vessels identified by HiSS in the rat images coincided with vasculature in the registered microCT image. The data demonstrate a strong correlation between tumor vasculature identified using HiSS and two gold standards: histology and microCT angiography.
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Affiliation(s)
- Chad R Haney
- Department of Radiology, University of Chicago, Chicago, IL 60637, USA.
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Wang K, Busse RF, Holmes JH, Beatty PJ, Brittain JH, Francois CJ, Reeder SB, Du J, Korosec FR. Interleaved variable density sampling with a constrained parallel imaging reconstruction for dynamic contrast-enhanced MR angiography. Magn Reson Med 2011; 66:428-36. [PMID: 21360740 DOI: 10.1002/mrm.22814] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 12/13/2010] [Accepted: 12/14/2010] [Indexed: 11/09/2022]
Abstract
For MR applications such as contrast-enhanced MR angiography, it is desirable to achieve simultaneously high spatial and temporal resolution. The current clinical standard uses view-sharing methods combined with parallel imaging; however, this approach still provides limited spatial and temporal resolution. To improve on the clinical standard, we present an interleaved variable density (IVD) sampling method that pseudorandomly undersamples each individual frame of a 3D Cartesian ky-kz plane combined with parallel imaging acceleration. From this dataset, time-resolved images are reconstructed with a method that combines parallel imaging with a multiplicative constraint. Total acceleration factors on the order of 20 are achieved for contrast-enhanced MR angiography of the lower extremities, and improvements in temporal fidelity of the depiction of the contrast bolus passage are demonstrated relative to the clinical standard.
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Affiliation(s)
- Kang Wang
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705-2275, USA
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Haider CR, Borisch EA, Glockner JF, Mostardi PM, Rossman PJ, Young PM, Riederer SJ. Max CAPR: high-resolution 3D contrast-enhanced MR angiography with acquisition times under 5 seconds. Magn Reson Med 2011; 64:1171-81. [PMID: 20715291 DOI: 10.1002/mrm.22434] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
High temporal and spatial resolution is desired in imaging of vascular abnormalities having short arterial-to-venous transit times. Methods that exploit temporal correlation to reduce the observed frame time demonstrate temporal blurring, obfuscating bolus dynamics. Previously, a Cartesian acquisition with projection reconstruction-like (CAPR) sampling method has been demonstrated for three-dimensional contrast-enhanced angiographic imaging of the lower legs using two-dimensional sensitivity-encoding acceleration and partial Fourier acceleration, providing 1mm isotropic resolution of the calves, with 4.9-sec frame time and 17.6-sec temporal footprint. In this work, the CAPR acquisition is further undersampled to provide a net acceleration approaching 40 by eliminating all view sharing. The tradeoff of frame time and temporal footprint in view sharing is presented and characterized in phantom experiments. It is shown that the resultant 4.9-sec acquisition time, three-dimensional images sets have sufficient spatial and temporal resolution to clearly portray arterial and venous phases of contrast passage. It is further hypothesized that these short temporal footprint sequences provide diagnostic quality images. This is tested and shown in a series of nine contrast-enhanced MR angiography patient studies performed with the new method.
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Affiliation(s)
- Clifton R Haider
- MR Research Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
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Jagadeesan BD, Delgado Almandoz JE, Moran CJ, Benzinger TLS. Accuracy of susceptibility-weighted imaging for the detection of arteriovenous shunting in vascular malformations of the brain. Stroke 2010; 42:87-92. [PMID: 21088245 DOI: 10.1161/strokeaha.110.584862] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND AND PURPOSE to determine the accuracy of susceptibility-weighted MRI (SWI) for the detection of arteriovenous shunting (AVS) in vascular malformations of the brain (BVM). METHODS we retrospectively identified 60 patients who had been evaluated for known or suspected BVM by both SWI and digital subtraction angiography, without intervening treatment, during a 3-year period. SWI images were retrospectively assessed by 2 independent reviewers for the presence of AVS as determined by the presence of signal hyperintensity within a venous structure in the vicinity of the BVM. Discrepancies were resolved by consensus among a panel of 3 neuroradiologists. Accuracy parameters of SWI for the detection of AVS were calculated using digital subtraction angiography as the reference standard. RESULTS a total of 80 BVM were identified in the 60 patients included in our study. Of the 29 BVM with AVS on digital subtraction angiography, 14 were untreated arteriovenous malformations, 10 were previously treated arteriovenous malformations, and 5 were untreated dural arteriovenous fistulas. Overall, SWI was 93% sensitive and 98% specific for the detection of AVS in BVM, with excellent interobserver agreement (κ=0.94). In the 14 previously treated arteriovenous malformations, SWI was 100% sensitive and specific for the detection of AVS. In the 28 BVM associated with intracerebral hemorrhage, SWI was 100% sensitive and 96% specific for the detection of AVS. CONCLUSIONS SWI is accurate for the detection of arteriovenous shunting in vascular malformations of the brain and, for some patients, SWI may offer a noninvasive alternative to angiography in screening for or follow-up of treated BVM.
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Affiliation(s)
- Bharathi D Jagadeesan
- Division of Neuroradiology, Mallinckrodt Institute of Radiology, Washington University Campus, Saint Louis, MO 63110, USA.
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Peldschus K, Hamdorf M, Robert P, Port M, Adam G, Herborn CU. Comparison of the high relaxivity Gd chelates P1152 and Gd-BOPTA for contrast-enhanced MR angiography in rabbits at 1.5 Tesla and 3.0 Tesla. J Magn Reson Imaging 2010; 32:459-65. [DOI: 10.1002/jmri.22261] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Gerretsen SC, le Maire TF, Miller S, Thurnher SA, Herborn CU, Michaely HJ, Kramer H, Vanzulli A, Vymazal J, Wasser MN, Ballarati CEM, Kirchin MA, Pirovano G, Leiner T. Multicenter, double-blind, randomized, intraindividual crossover comparison of gadobenate dimeglumine and gadopentetate dimeglumine for MR angiography of peripheral arteries. Radiology 2010; 255:988-1000. [PMID: 20501735 DOI: 10.1148/radiol.10090357] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To prospectively compare the image quality and diagnostic performance achieved with doses of gadobenate dimeglumine and gadopentetate dimeglumine of 0.1 mmol per kilogram of body weight in patients undergoing contrast material-enhanced magnetic resonance (MR) angiography of the pelvis, thigh, and lower-leg (excluding foot) for suspected or known peripheral arterial occlusive disease. MATERIALS AND METHODS Institutional review board approval was granted from each center and informed written consent was obtained from all patients. Between November 2006 and January 2008, 96 patients (62 men, 34 women; mean age, 63.7 years +/- 10.4 [standard deviation]; range, 39-86 years) underwent two identical examinations at 1.5 T by using three-dimensional spoiled gradient-echo sequences and randomized 0.1-mmol/kg doses of each agent. Images were evaluated on-site for technical adequacy and quality of vessel visualization and offsite by three independent blinded readers for anatomic delineation and detection/exclusion of pathologic features. Comparative diagnostic performance was determined in 31 patients who underwent digital subtraction angiography. Data were analyzed by using the Wilcoxon signed-rank, McNemar, and Wald tests. Interreader agreement was determined by using generalized kappa statistics. Differences in quantitative contrast enhancement were assessed and a safety evaluation was performed. RESULTS Ninety-two patients received both agents. Significantly better performance (P < .0001; all evaluations) with gadobenate dimeglumine was noted on-site for technical adequacy and vessel visualization quality and offsite for anatomic delineation and detection/exclusion of pathologic features. Contrast enhancement (P < or = .0001) and detection of clinically relevant disease (P < or = .0028) were significantly improved with gadobenate dimeglumine. Interreader agreement for stenosis detection and grading was good to excellent (kappa = 0.749 and 0.805, respectively). Mild adverse events were reported for four (six events) and five (eight events) patients after gadobenate dimeglumine and gadopentetate dimeglumine, respectively. CONCLUSION Higher-quality vessel visualization, greater contrast enhancement, fewer technical failures, and improved diagnostic performance are obtained with gadobenate dimeglumine, relative to gadopentetate dimeglumine, when compared intraindividually at 0.1-mmol/kg doses in patients undergoing contrast-enhanced MR angiography for suspected peripheral arterial occlusive disease.
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Affiliation(s)
- Suzanne C Gerretsen
- Dept of Cardiovascular MR Research, Maastricht Univ Hosp, Peter Debijelaan 25, 6229HX Maastricht, the Netherlands
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Prieto C, Uribe S, Razavi R, Atkinson D, Schaeffter T. 3D undersampled golden‐radial phase encoding for DCE‐MRA using inherently regularized iterative SENSE. Magn Reson Med 2010; 64:514-26. [DOI: 10.1002/mrm.22446] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Claudia Prieto
- King's College London, Division of Imaging Sciences, NIHR Biomedical Research Centre at Guy's & St Thomas' Foundation Trust London, United Kingdom
| | - Sergio Uribe
- King's College London, Division of Imaging Sciences, NIHR Biomedical Research Centre at Guy's & St Thomas' Foundation Trust London, United Kingdom
- Pontificia Universidad Católica de Chile, Radiology Department, School of Medicine, Center for Biomedical Imaging, Santiago, Chile
| | - Reza Razavi
- King's College London, Division of Imaging Sciences, NIHR Biomedical Research Centre at Guy's & St Thomas' Foundation Trust London, United Kingdom
| | - David Atkinson
- Centre for Medical Image Computing, University College London, London, United Kingdom
| | - Tobias Schaeffter
- King's College London, Division of Imaging Sciences, NIHR Biomedical Research Centre at Guy's & St Thomas' Foundation Trust London, United Kingdom
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MAI WILFRIED, WEISSE CHICK, SLEEPER MEGM. CARDIAC MAGNETIC RESONANCE IMAGING IN NORMAL DOGS AND TWO DOGS WITH HEART BASE TUMOR. Vet Radiol Ultrasound 2010; 51:428-35. [DOI: 10.1111/j.1740-8261.2010.01673.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Waugh SA, Ramkumar PG, Gandy SJ, Nicholas RS, Martin P, Belch JJF, Struthers AD, Houston JG. Optimization of the contrast dose and injection rates in whole-body MR angiography at 3.0T. J Magn Reson Imaging 2010; 30:1059-67. [PMID: 19856438 DOI: 10.1002/jmri.21930] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To optimize the contrast agent dose and delivery rate used in a novel whole-body magnetic resonance angiography (MRA) protocol using a 3.0T MR scanner. MATERIALS AND METHODS Six groups of 20 consenting volunteers underwent whole-body MRA, with each group receiving a different contrast dose and contrast delivery rate. The arterial tree was divided into 16 segments and the image quality at each of the anatomical locations, covering the whole body, was assessed. Qualitative analysis was carried out using a scoring assessment of image quality, and quantitative assessments were performed by measuring contrast-to-noise (CNR) and a signal-to-noise (SNR) index. RESULTS Reducing the contrast dose from 40 mL to 25 mL was found to significantly increase the CNR in several vessels of interest in the arterial tree. There was also a significant increase in the qualitative image quality score (P < 0.001). CONCLUSION This study demonstrates that reducing the contrast dose at 3.0T can result in an increase in the CNR in the vessels of interest without significantly affecting the SNR.
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Affiliation(s)
- Shelley A Waugh
- Department of Medical Physics, Ninewells Hospital, NHS Tayside, Dundee, UK.
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Martin DR, Semelka RC, Chapman A, Peters H, Finn PJ, Kalb B, Thomsen H. Nephrogenic systemic fibrosis versus contrast-induced nephropathy: Risks and benefits of contrast-enhanced MR and CT in renally impaired patients. J Magn Reson Imaging 2009; 30:1350-6. [PMID: 19937934 DOI: 10.1002/jmri.21968] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Diego R Martin
- Department of Radiology, Emory University School of Medicine, Atlanta, Georgia, USA.
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New dual mode gadolinium nanoparticle contrast agent for magnetic resonance imaging. PLoS One 2009; 4:e7628. [PMID: 19893616 PMCID: PMC2764087 DOI: 10.1371/journal.pone.0007628] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 10/01/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Liposomal-based gadolinium (Gd) nanoparticles have elicited significant interest for use as blood pool and molecular magnetic resonance imaging (MRI) contrast agents. Previous generations of liposomal MR agents contained gadolinium-chelates either within the interior of liposomes (core-encapsulated gadolinium liposomes) or presented on the surface of liposomes (surface-conjugated gadolinium liposomes). We hypothesized that a liposomal agent that contained both core-encapsulated gadolinium and surface-conjugated gadolinium, defined herein as dual-mode gadolinium (Dual-Gd) liposomes, would result in a significant improvement in nanoparticle-based T1 relaxivity over the previous generations of liposomal agents. In this study, we have developed and tested, both in vitro and in vivo, such a dual-mode liposomal-based gadolinium contrast agent. METHODOLOGY/PRINCIPAL FINDINGS THREE TYPES OF LIPOSOMAL AGENTS WERE FABRICATED: core-encapsulated, surface-conjugated and dual-mode gadolinium liposomes. In vitro physico-chemical characterizations of the agents were performed to determine particle size and elemental composition. Gadolinium-based and nanoparticle-based T1 relaxivities of various agents were determined in bovine plasma. Subsequently, the agents were tested in vivo for contrast-enhanced magnetic resonance angiography (CE-MRA) studies. Characterization of the agents demonstrated the highest gadolinium atoms per nanoparticle for Dual-Gd liposomes. In vitro, surface-conjugated gadolinium liposomes demonstrated the highest T1 relaxivity on a gadolinium-basis. However, Dual-Gd liposomes demonstrated the highest T1 relaxivity on a nanoparticle-basis. In vivo, Dual-Gd liposomes resulted in the highest signal-to-noise ratio (SNR) and contrast-to-noise ratio in CE-MRA studies. CONCLUSIONS/SIGNIFICANCE The dual-mode gadolinium liposomal contrast agent demonstrated higher particle-based T1 relaxivity, both in vitro and in vivo, compared to either the core-encapsulated or the surface-conjugated liposomal agent. The dual-mode gadolinium liposomes could enable reduced particle dose for use in CE-MRA and increased contrast sensitivity for use in molecular imaging.
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Kotys MS, Herzka DA, Vonken EJ, Ohayon J, Heroux J, Gharib AM, Stuber M, Pettigrew RI. Profile order and time-dependent artifacts in contrast-enhanced coronary MR angiography at 3T: origin and prevention. Magn Reson Med 2009; 62:292-9. [PMID: 19526488 DOI: 10.1002/mrm.21997] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
To enhance the clinical value of coronary magnetic resonance angiography (MRA), high-relaxivity contrast agents have recently been used at 3T. Here we examine a uniform bilateral shadowing artifact observed along the coronary arteries in MRA images collected using such a contrast agent. Simulations were performed to characterize this artifact, including its origin, to determine how best to mitigate this effect, and to optimize a data acquisition/injection scheme. An intraluminal contrast agent concentration model was used to simulate various acquisition strategies with two profile orders for a slow-infusion of a high-relaxivity contrast agent. Filtering effects from temporally variable weighting in k-space are prominent when a centric, radial (CR) profile order is applied during contrast infusion, resulting in decreased signal enhancement and underestimation of vessel width, while both pre- and postinfusion steady-state acquisitions result in overestimation of the vessel width. Acquisition during the brief postinfusion steady-state produces the greatest signal enhancement and minimizes k-space filtering artifacts.
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Affiliation(s)
- Melanie S Kotys
- National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland 20892-2281, USA
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Haider CR, Glockner JF, Stanson AW, Riederer SJ. Peripheral vasculature: high-temporal- and high-spatial-resolution three-dimensional contrast-enhanced MR angiography. Radiology 2009; 253:831-43. [PMID: 19789238 DOI: 10.1148/radiol.2533081744] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To prospectively evaluate the feasibility of performing high-spatial-resolution (1-mm isotropic) time-resolved three-dimensional (3D) contrast material-enhanced magnetic resonance (MR) angiography of the peripheral vasculature with Cartesian acquisition with projection-reconstruction-like sampling (CAPR) and eightfold accelerated two-dimensional (2D) sensitivity encoding (SENSE). MATERIALS AND METHODS All studies were approved by the institutional review board and were HIPAA compliant; written informed consent was obtained from all participants. There were 13 volunteers (mean age, 41.9; range, 27-53 years). The CAPR sequence was adapted to provide 1-mm isotropic spatial resolution and a 5-second frame time. Use of different receiver coil element sizes for those placed on the anterior-to-posterior versus left-to-right sides of the field of view reduced signal-to-noise ratio loss due to acceleration. Results from eight volunteers were rated independently by two radiologists according to prominence of artifact, arterial to venous separation, vessel sharpness, continuity of arterial signal intensity in major arteries (anterior and posterior tibial, peroneal), demarcation of origin of major arteries, and overall diagnostic image quality. MR angiographic results in two patients with peripheral vascular disease were compared with their results at computed tomographic angiography. RESULTS The sequence exhibited no image artifact adversely affecting diagnostic image quality. Temporal resolution was evaluated to be sufficient in all cases, even with known rapid arterial to venous transit. The vessels were graded to have excellent sharpness, continuity, and demarcation of the origins of the major arteries. Distal muscular branches and the communicating and perforating arteries were routinely seen. Excellent diagnostic quality rating was given for 15 (94%) of 16 evaluations. CONCLUSION The feasibility of performing high-diagnostic-quality time-resolved 3D contrast-enhanced MR angiography of the peripheral vasculature by using CAPR and eightfold accelerated 2D SENSE has been demonstrated.
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Affiliation(s)
- Clifton R Haider
- MR Research Laboratory and Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
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Mostardi PM, Haider CR, Rossman PJ, Borisch EA, Riederer SJ. Controlled experimental study depicting moving objects in view-shared time-resolved 3D MRA. Magn Reson Med 2009; 62:85-95. [PMID: 19319897 DOI: 10.1002/mrm.21993] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Various methods have been used for time-resolved contrast-enhanced magnetic resonance angiography (CE-MRA), many involving view sharing. However, the extent to which the resultant image time series represents the actual dynamic behavior of the contrast bolus is not always clear. Although numerical simulations can be used to estimate performance, an experimental study can allow more realistic characterization. The purpose of this work was to use a computer-controlled motion phantom for study of the temporal fidelity of three-dimensional (3D) time-resolved sequences in depicting a contrast bolus. It is hypothesized that the view order of the acquisition and the selection of views in the reconstruction can affect the positional accuracy and sharpness of the leading edge of the bolus and artifactual signal preceding the edge. Phantom studies were performed using dilute gadolinium-filled vials that were moved along tabletop tracks by a computer-controlled motor. Several view orders were tested using view-sharing and Cartesian sampling. Compactness of measuring the k-space center, consistency of view ordering within each reconstruction frame, and sampling the k-space center near the end of the temporal footprint were shown to be important in accurate portrayal of the leading edge of the bolus. A number of findings were confirmed in an in vivo CE-MRA study.
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Eddleman CS, Jeong HJ, Hurley MC, Zuehlsdorff S, Dabus G, Getch CG, Batjer HH, Bendok BR, Carroll TJ. 4D radial acquisition contrast-enhanced MR angiography and intracranial arteriovenous malformations: quickly approaching digital subtraction angiography. Stroke 2009; 40:2749-53. [PMID: 19478223 PMCID: PMC2743532 DOI: 10.1161/strokeaha.108.546663] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The current gold standard for imaging intracranial AVMs involves catheter-based techniques, namely cerebral digital subtraction angiography (DSA). However, DSA presents some procedural risks to the patient. Unfortunately, AVM patients usually undergo multiple DSA exams throughout their diagnostic and therapeutic course, significantly increasing their procedural risk exposure. As such, high-quality noninvasive imaging is desired. We hypothesize that 4D radial acquisition contrast-enhanced MRA approximates the vascular architecture and hemodynamics of AVMs compared to conventional angiography. METHODS Thirteen consecutive AVM patients were assessed by 4D radial acquisition contrast-enhanced MRA and DSA. The 4D rCE-MRA images were independently assessed regarding the location, nidal size, Spetzler-Martin grade, and identification of arterial feeders, drainage pattern, and any other vascular anomalies. RESULTS 4D rCE-MRA correctly depicted the size, venous drainage pattern, and prominent arterial feeders in all cases. Spetzler-Martin grade was correctly determined between reviewers and between the different imaging modalities in all cases except 1. The nidus size was in good correlation between the reviewers, where r=0.99, P<0.000001. There was very good agreement between reviewers regarding the individual scans (kappa=0.63 to 1), whereas the agreement between the DSA and 4D rCE-MRA images was also good (kappa=0.61 to 0.85). CONCLUSIONS We have developed a 4D radial acquisition contrast-enhanced MRA sequence capable of imaging intracranial AVMs approximating that of DSA. Image analysis demonstrates equivalency in terms of grading AVMs using the Spetzler-Martin grading scale. This 4D rCE-MRA sequence has the potential to avoid some applications of DSA, thus saving patients from potential procedural risks.
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Affiliation(s)
- Christopher S Eddleman
- Department of Neurological Surgery Feinberg School of Medicine, Northwestern University, 676 North St Clair Ste 2210, Chicago, IL 60611, USA.
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Gadofosveset-enhanced MR angiography of the pedal arteries in patients with diabetes mellitus and comparison with selective intraarterial DSA. Eur Radiol 2009; 19:2993-3001. [DOI: 10.1007/s00330-009-1501-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 05/12/2009] [Accepted: 05/22/2009] [Indexed: 01/23/2023]
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Menke J, Helms G, Larsen J. Viewing the effective k-space coverage of MR images: phantom experiments with fast Fourier transform. Magn Reson Imaging 2009; 28:87-94. [PMID: 19553053 DOI: 10.1016/j.mri.2009.05.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 03/23/2009] [Accepted: 05/10/2009] [Indexed: 11/29/2022]
Abstract
The purpose of this experimental study was to evaluate whether the effective k-space coverage of MR images can in principle be viewed after multidimensional Fourier transform back to k-space. A water-soaked sponge phantom providing homogeneous k-space pattern was imaged with different standard MR sequences, utilizing elliptic acquisitions, partial-Fourier acquisitions and elliptic filtering as imaging examples. The resulting MR images were Fourier-transformed to the spatial frequency domain (the k-space) to visualize their effective k-space coverage. These frequency domain images are named "backtransformed k-space images." For a quantitative assessment, the sponge phantom was imaged with three-dimensional partial-Fourier sequences while varying the partial acquisition parameters in slice and phase direction. By linear regression analysis, the k-space coverage as expected from the sequence menu parameters was compared to the effective k-space coverage as observed in the backtransformed k-space images. The k-space coverage of elliptic and partial-Fourier acquisitions became visible in the backtransformed k-space images, as well as the effect of elliptic filtering. The expected and the observed k-space coverage showed a highly significant correlation (r=.99, P<.001). In conclusion, the effective k-space coverage of MR images becomes visible when Fourier-transforming MR images of a sponge phantom back to k-space. This method could be used for several purposes including sequence parameter optimization, basic imaging research, and to enhance a visual understanding of k-space, especially in three-dimensional MR imaging.
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Affiliation(s)
- Jan Menke
- Department of Diagnostic Radiology, University Hospital, Goettingen, Germany.
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Oostendorp M, Post MJ, Backes WH. Vessel growth and function: depiction with contrast-enhanced MR imaging. Radiology 2009; 251:317-35. [PMID: 19401568 DOI: 10.1148/radiol.2512080485] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Magnetic resonance (MR) imaging is a versatile noninvasive diagnostic tool that can be applied to the entire human body to revealing morphologic, functional, and metabolic information. The authors review how MR imaging can depict both the established and the developing vasculature with techniques involving intravenously administered contrast agents. In addition to macrovascular morphology and flow, MR imaging is able to exploit microvascular properties, including vessel size distribution, hyperpermeability, flow heterogeneity, and possibly also upregulation of endothelial biomarkers. For each MR method, the basic principles, potential acquisition and interpretation pitfalls, solutions, and applications are described. Furthermore, discussion includes current shortcomings and the impact of future developments (eg, higher magnetic field strength systems, targeted macromolecular contrast agents) on the visualization of blood vessel growth and function with contrast-enhanced MR imaging.
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Affiliation(s)
- Marlies Oostendorp
- Department of Radiology, Maastricht University Medical Centre, P. Debyelaan 25, 6229 HX Maastricht, the Netherlands
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72
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Beranek-Chiu J, Froehlich JM, Wentz KU, Doert AN, Zollikofer CL, Eckhardt BP. Improved vessel delineation in keyhole time-resolved contrast-enhanced MR angiography using a gadolinium doped flush. J Magn Reson Imaging 2009; 29:1147-53. [PMID: 19388120 DOI: 10.1002/jmri.21761] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To prospectively assess the influence of a gadolinium doped saline flush compared with a pure saline flush on the image quality of the supra-aortic vessels using time-resolved contrast-enhanced MR angiography (4D CE-MRA) in a randomized double blind clinical trial. MATERIALS AND METHODS Twenty-two patients scheduled for contrast-enhanced craniocerebral MRI underwent a supplemental 4D CE-MRA covering the carotids to the superior sinus consisting of 30 dynamics of a T1-weighted 3D gradient-echo sequence (FFE) in sagittal direction. The temporal resolution of 1.1 s per dataset was achieved using the keyhole technique with the reference scan acquired at the end. Immediately after the intravenous (IV) injection of 0.1 mmol Gd/kg body weight of gadoterate, our patients received a 50-mL flush consisting either of a 0.9% saline solution (n = 11) or doped with 50 mM gadolinium (n = 11; total Gd: 0.11 mmol/kg) at a flow-rate of 2 mL/s. Vessel delineation, image quality, signal-to-noise- (SNR) and contrast-to-noise (CNR) ratios over time were compared. RESULTS Both vessel delineation (internal carotid artery [ICA]: slope(saline) = 308.5; slope(Gd) = 528.9; P = 0.006; superior sagittal sinus [SSS]: slope(saline) = 505.3; slope(Gd) = 674.9; P = 0.007) and CNR (ICA: CNR(saline) = 57.3; CNR(Gd) = 80.55; P = 0.0417; SSS: CNR(saline) = 74.15; CNR(Gd) = 117.4; P = 0.0331) of the ICA and SSS were significantly increased using the gadolinium doped flush. CONCLUSION A low concentrated gadolinium flush in comparison to a pure saline flush improves significantly vessel contrast and their delineation in time-resolved CE-MRA using the keyhole technique.
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Affiliation(s)
- Jan Beranek-Chiu
- Cantonal Hospital, Department of Radiology, Winterthur, Switzerland
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73
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Menke J. Carotid MR angiography with traditional bolus timing: clinical observations and Fourier-based modelling of contrast kinetics. Eur Radiol 2009; 19:2654-62. [PMID: 19449013 PMCID: PMC2762047 DOI: 10.1007/s00330-009-1448-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Accepted: 04/04/2009] [Indexed: 11/30/2022]
Abstract
This study analyses the relation between image quality and contrast kinetics in bolus-timed carotid magnetic resonance angiography (MRA) and interprets the findings by Fourier-based numerical modelling. One hundred patients prone to carotid stenosis were studied using contrast-enhanced carotid MRA with bolus timing. The carotid MRAs were timed to start relatively early without accounting for the injection time of the contrast medium. For interpretation different starting times were modelled, utilising the spectral information of the test bolus series. In the test bolus series the arterial time-to-peak showed a large 95% confidence interval of 12-27 s, indicating the need for individual MRA timing. All bolus-timed MRAs were of good diagnostic quality. The mean (+/-SD) arterial contrast-to-noise ratio was 53.0 (+/-12.8) and thus high, and 95% of the MRAs showed a slight venous contamination of 11.8% or less (median 5.6%). According to the Fourier-based modelling the central k-space may be acquired about 2 s before the arterial contrast peak. This results in carotid MRAs with sufficiently high arterial enhancement and little venous contamination. In conclusion, in bolus-timed carotid MRA a relatively short timing provides good arterial contrast with little venous contamination, which can be explained by Fourier-based numerical modelling of the contrast kinetics.
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Affiliation(s)
- Jan Menke
- Department of Diagnostic Radiology, University Hospital, Robert-Koch-Strasse 40, 37075 Goettingen, Germany.
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74
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Haider CR, Hu HH, Campeau NG, Huston J, Riederer SJ. 3D high temporal and spatial resolution contrast-enhanced MR angiography of the whole brain. Magn Reson Med 2009; 60:749-60. [PMID: 18727101 DOI: 10.1002/mrm.21675] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sensitivity encoding (SENSE) and partial Fourier techniques have been shown to reduce the acquisition time and provide high diagnostic quality images. However, for time-resolved acquisitions there is a need for both high temporal and spatial resolution. View sharing can be used to provide an increased frame rate but at the cost of acquiring spatial frequencies over a duration longer than a frame time. In this work we hypothesize that a CArtesian Projection Reconstruction-like (CAPR) technique in combination with 2D SENSE, partial Fourier, and view sharing can provide 1-2 mm isotropic resolution with sufficient temporal resolution to distinguish intracranial arterial and venous phases of contrast passage in whole-brain angiography. In doing so, the parameter of "temporal footprint" is introduced as a descriptor for characterizing and comparing time-resolved view-shared pulse sequences. It is further hypothesized that short temporal footprint sequences have higher temporal fidelity than similar sequences with longer temporal footprints. The tradeoff of temporal footprint and temporal acceleration is presented and characterized in numerical simulations. Results from 11 whole-brain contrast-enhanced MR angiography studies with the new method with SENSE acceleration factors R = 4 and 5.3 are shown to provide images of comparable or higher diagnostic quality than the unaccelerated reference.
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Affiliation(s)
- Clifton R Haider
- MR Research Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
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76
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78
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Knauth Meadows A, Ordovas K, Higgins CB, Reddy GP. Magnetic resonance imaging in the adult with congenital heart disease. Semin Roentgenol 2008; 43:246-58. [PMID: 18486685 DOI: 10.1053/j.ro.2008.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Alison Knauth Meadows
- Department of Radiology, University of California, San Francisco, San Francisco, California 94143-0628, USA
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79
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80
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Magnetic Resonance-Guided Angioplasty With Delivery of Contrast-Media Doped Solutions to the Vessel Wall: An Experimental Study in Swine. Invest Radiol 2008; 43:530-7. [DOI: 10.1097/rli.0b013e31817ee519] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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81
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Ley S, Kauczor HU. MR Imaging/Magnetic Resonance Angiography of the Pulmonary Arteries and Pulmonary Thromboembolic Disease. Magn Reson Imaging Clin N Am 2008; 16:263-73, ix. [PMID: 18474331 DOI: 10.1016/j.mric.2008.02.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Sebastian Ley
- Department of Pediatric Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 153, 69120 Heidelberg, Germany.
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82
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Muhs BE, Verhagen HJM, Huddle MG, Pai VM, Hecht EM, Dardik A. Theory, technique, and practice of magnetic resonance angiography. Vascular 2008; 15:376-83. [PMID: 18053424 DOI: 10.2310/6670.2007.00052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Magnetic resonance angiography (MRA) is now a widely accepted technique used to characterize vascular pathology such as stenosis, dissection, fistula, and aneurysms. Magnetic resonance techniques are increasingly driving clinical decision making by vascular physicians. The physics behind MRA can contribute to the general understanding and interpretation of the anatomic images. We seek to provide a window into how magnetic resonance images are generated, which techniques may be employed, and the potential advantages and limitations of various techniques and to discuss the future role MRA may have for the vascular physician.
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Affiliation(s)
- Bart E Muhs
- Department of Surgery, Section of Vascular Surgery, Yale University School of Medicine, New Haven, CT 06510, USA.
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83
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Abu-Alfa A. The impact of NSF on the care of patients with kidney disease. J Am Coll Radiol 2008; 5:45-52. [PMID: 18180009 DOI: 10.1016/j.jacr.2007.08.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Indexed: 01/08/2023]
Abstract
The association of nephrogenic systemic fibrosis (NSF) with the use of gadolinium-based magnetic resonance contrast agents (GBMCAs) has greatly affected the care of patients with kidney disease. Nephrogenic systemic fibrosis has been reported in patients with end-stage renal disease, chronic kidney disease (CKD) and acute kidney injury. The majority of cases have occurred in patients with end-stage renal disease, but cases of NSF have been reported in CKD patients with glomerular filtration rates less than 30 mL/min/1.73 m(2). Odds ratios have ranged between 8.97 and 32.5 among patients exposed to GBMCAs. Given the significant morbidity, disability, and mortality associated with NSF, it is imperative to properly and preemptively identify those patients at risk. Patients with end-stage renal disease seem to be at highest risk, particularly those maintained on peritoneal dialysis (PD). Although there are no data to support a role for hemodialysis in reducing the risk for NSF after the administration of GBMCAs, hemodialysis is recommended within 2 to 3 hours. Patients maintained on PD and those with CKD present a challenge, as they do not typically have vascular access for hemodialysis, yet the clearance of GBMCAs is very low, and it may be prudent to consider hemodialysis especially for PD patients. Gadolinium-based magnetic resonance contrast agents are removed by dialysis, with estimates that about 99% of a dose is removed after 3 to 4 sessions of hemodialysis. The elimination half-life averaged 9 hours in patients with stage 4 CKD (glomerular filtration rate <30 mL/min/1.73 m(2)) compared with 1.5 hours in those with normal glomerular filtration rates. This prolonged elimination and longer exposure may be important factors in predisposing to NSF.
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Affiliation(s)
- Ali Abu-Alfa
- Department of Internal Medicine, Section of Nephrology, Yale School of Medicine, New Haven, Connecticut 06510-8042, USA.
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84
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Krishnam MS, Tomasian A, Lohan DG, Tran L, Finn JP, Ruehm SG. Low-dose, time-resolved, contrast-enhanced 3D MR angiography in cardiac and vascular diseases: correlation to high spatial resolution 3D contrast-enhanced MRA. Clin Radiol 2008; 63:744-55. [PMID: 18555032 DOI: 10.1016/j.crad.2008.01.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Revised: 12/22/2007] [Accepted: 01/03/2008] [Indexed: 11/20/2022]
Abstract
AIM To evaluate the effectiveness of low-dose, contrast-enhanced, time-resolved, three-dimensional (3D) magnetic resonance (MR) angiography (TR-MRA) in the assessment of various cardiac and vascular diseases, and to compare the results with high-resolution contrast-enhanced MRA (CE-MRA). MATERIALS AND METHODS Thirty consecutive patients underwent contrast-enhanced 3D TR-MRA and high spatial resolution 3D CE-MRA for evaluation of cardiac and thoracic vascular diseases at 1.5 T, and neurovascular, abdominal and peripheral vascular diseases at 3T. Gadolinium-based contrast medium was administered at a constant dose of 5 ml for TR-MRA, and 20 ml (lower extremity 30 ml) for CE-MRA. Two readers evaluated image quality using a four-point scale (from 0=excellent to 3=non-diagnostic), artefacts and findings on both datasets. Interobserver variability was tested with kappa coefficient. RESULTS The overall image quality for TR-MRA was in the diagnostic range (median 0, range 0-1; k=0.74). Readers demonstrated important additional dynamic information on TR-MRA in 28 of 30 patients (k=0.84). Confident evaluation of organ perfusion (n=23), arteriovenous malformation/fistula flow patterns (n=7), exclusion of intra-cardiac shunts (n=6), and assessment of stent and conduit patency (n=5) were performed by both readers using TR-MRA. Readers demonstrated fine vascular details with higher confidence in 10 patients on CE-MRA. Using CE-MRA, Reader 1 and 2 depicted anatomical details in 6 and 5 patients, respectively, only on CE-MRA. CONCLUSION Low-dose TR-MRA yields rapid and important functional and anatomical information in patients with cardiac and vascular diseases. Due to limited spatial resolution, TR-MRA is inferior to CE-MRA in demonstrating fine vascular details.
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Affiliation(s)
- M S Krishnam
- Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, CA 90095-7206, USA.
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85
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Kos S, Huegli R, Bongartz GM, Jacob AL, Bilecen D. MR-guided endovascular interventions: a comprehensive review on techniques and applications. Eur Radiol 2007; 18:645-57. [PMID: 18071710 DOI: 10.1007/s00330-007-0818-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2007] [Revised: 10/01/2007] [Accepted: 10/30/2007] [Indexed: 10/22/2022]
Abstract
The magnetic resonance (MR) guidance of endovascular interventions is probably one of the greatest challenges of clinical MR research. MR angiography is not only an imaging tool for the vasculature but can also simultaneously depict high tissue contrast, including the differentiation of the vascular wall and perivascular tissues, as well as vascular function. Several hurdles had to be overcome to allow MR guidance for endovascular interventions. MR hardware and sequence design had to be developed to achieve acceptable patient access and to allow real-time or near real-time imaging. The development of interventional devices, both applicable and safe for MR imaging (MRI), was also mandatory. The subject of this review is to summarize the latest developments in real-time MRI hardware, MRI, visualization tools, interventional devices, endovascular tracking techniques, actual applications and safety issues.
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Affiliation(s)
- Sebastian Kos
- Institute of Radiology, Division of Interventional Radiology, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
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86
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Hansen T, Ahlström H, Johansson L. Whole-body screening of atherosclerosis with magnetic resonance angiography. Top Magn Reson Imaging 2007; 18:329-337. [PMID: 18025987 DOI: 10.1097/rmr.0b013e318159aaa2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
With whole-body magnetic resonance angiography (WBMRA), it is possible to examine the whole arterial tree except intracranial and coronary vessels in a single examination without the risks involved in ionizing radiation or arterial cannulation. Whole-body magnetic resonance angiography is well suited for repeated clinical examinations in patients with systemic diseases such as vasculitis or atherosclerosis and can also be used for scientific purposes. On the basis of the WBMRA overview, a possible further development of the WBMRA concept can be to perform further acquisitions at sites with atherosclerotic plaques with higher-resolution scans to determine the degree of stenosis more accurately or to achieve plaque characterization. A total validation of WBMRA compared with digital subtraction angiography (DSA) is not possible owing to the hazards of ionizing radiation. Studies have shown a high sensitivity and specificity for the pelvic and lower limb arteries in comparison with DSA. No systematic validation against DSA has been performed for the renal, aortic, and carotid arteries. Various methods have been used, however, for confirmation of vascular abnormalities found on WBMRA such as ultrasonography, dedicated MRA, or DSA, with reasonably high agreement. The WBMRA method has not been studied with regard to prediction of future cardiovascular (CV) events, as have intima media thickness, coronary artery calcium scoring, and the ankle-brachial index. The full usefulness of WBMRA in an epidemiological setting and as a complementary screening tool for assessing CV risk still needs to be validated against future CV events.
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Affiliation(s)
- Tomas Hansen
- Department of Radiology, Uppsala University Hospital, Uppsala, Sweden.
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87
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Pérez-Mayoral E, Soler-Padrós J, Negri V, Cerdán S, Ballesteros P. Synthetic approaches to heterocyclic ligands for Gd-based MRI contrast agents. Molecules 2007; 12:1771-95. [PMID: 17960087 PMCID: PMC6149094 DOI: 10.3390/12081771] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 08/03/2007] [Accepted: 08/03/2007] [Indexed: 11/17/2022] Open
Abstract
Magnetic Resonance Imaging (MRI) methods are currently used in the clinic for the non invasive detection and characterization of a wide variety of pathologies. Increases in the diagnostic efficiency of MRI have been helped by both the design of dedicated MR sequences revealing specific aspects of the pathology and by the development of more sensitive and selective Contrast Agents (CAs), capable of more precisely delineating the borderline regions. In the present review we focus on the synthetic strategies used to obtain MRI CAs containing heterocyclic rings.
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Affiliation(s)
- Elena Pérez-Mayoral
- Laboratorio de Síntesis Orgánica e Imagen Molecular por Resonancia Magnética, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid, Spain
- Departamento de Química Inorgánica y Química Técnica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid, Spain
| | - Jordi Soler-Padrós
- Laboratorio de Síntesis Orgánica e Imagen Molecular por Resonancia Magnética, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid, Spain
| | - Viviana Negri
- Laboratorio de Síntesis Orgánica e Imagen Molecular por Resonancia Magnética, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid, Spain
| | - Sebastián Cerdán
- Laboratorio de Imagen Espectroscópica por Resonancia Magnética (LIERM), Instituto de Investigaciones Biomédicas “Alberto Sols”, CSIC/UAM, C/ Arturo Duperier 4, E-28029 Madrid, Spain
| | - Paloma Ballesteros
- Laboratorio de Síntesis Orgánica e Imagen Molecular por Resonancia Magnética, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid, Spain
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Chang Z, Xiang QS. Simplified skipped phase encoding and edge deghosting (SPEED) for imaging sparse objects with applications to MRA. Med Phys 2007; 34:3173-82. [PMID: 17879780 DOI: 10.1118/1.2750966] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The fast imaging method named skipped phase encoding and edge deghosting (SPEED) has been demonstrated to reduce scan time considerably with typical magnetic resonance imaging data. In this work, SPEED is simplified with improved efficiency to accelerate the scan of sparse objects; we refer to this method as S-SPEED. S-SPEED partially samples k-space into two interleaved data sets, each with the same skip size of N but a different relative shift in phase encoding. The sampled data are then Fourier transformed into two ghosted images with N aliasing ghosts. Given the sparseness of signal distribution, the ghosted images are simply modeled with a single-layer structure, analogous to that used in maximum-intensity projection. With an algorithm based on a least-square-error solution, a deghosted image is solved, and a residual map is output for quality control. S-SPEED can be generalized to include more layers with additional acquisitions for refined results. Without differential filtering and full central k-space sampling, S-SPEED reduces scan time further and achieves more straightforward reconstruction, as compared with SPEED. In this work, S-SPEED is applied to accelerate magnetic resonance angiography (MRA) by taking advantage of the sparse nature of MRA data. With sparse phantom data and in vivo phase contrast MRA data, S-SPEED is demonstrated to achieve satisfactory results with an acceleration factor of 5.5 using a single coil.
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Affiliation(s)
- Zheng Chang
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada.
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89
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Partain CL. On the potential causal relationship between gadolinium-containing MRI agents and nephrogenic systemic fibrosis. J Magn Reson Imaging 2007; 25:879-80. [PMID: 17457806 DOI: 10.1002/jmri.20982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
OBJECTIVE To expatiate on the possible advantages and disadvantages of high magnetic field strengths for magnetic resonance imaging and, in particular, for magnetic resonance angiography. METHODS AND RESULTS A review of the available literature is given, presenting many of the advantages and disadvantages of imaging at higher field strengths. Focus is put on imaging at 3 to 7 T. Early results at 7 T are presented; these results indicate that several of the angiographic techniques commonly used at lower field strengths show promise for improvement by taking advantage of the higher signal and susceptibility sensitivity at 7 T. CONCLUSIONS The drive toward higher field strengths, both for the purpose of fundamental research and for clinical diagnostic imaging, is likely to continue. New applications using the unique properties of high field strength will almost certainly emerge as researchers gain more experience. The ultimate limiting factor is likely to be the physiological effects at high field strengths. However, this limit seems to lie at field strengths higher than 7 T because early experience shows good tolerance of 7 T examinations.
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Affiliation(s)
- Mark E Ladd
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany.
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91
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Kreitner KF, Kunz RP, Herber S, Martenstein S, Dorweiler B, Dueber C. MR angiography of the pedal arteries with gadobenate dimeglumine, a contrast agent with increased relaxivity, and comparison with selective intraarterial DSA. J Magn Reson Imaging 2007; 27:78-85. [DOI: 10.1002/jmri.21226] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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92
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Marzella L, Blank M, Gelperin K, Johann-Liang R. Safety risks with gadolinium-based contrast agents. J Magn Reson Imaging 2007; 26:816; author reply 817. [PMID: 17685423 DOI: 10.1002/jmri.21021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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