Magnetic resonance imaging clinics of North America
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Imaging of the arteries of the lower extremity is most often performed in patients who have known or suspected peripheral artery occlusive disease. Due to the recent advances in imaging modalities, the radiologic approach to the diagnosis of peripheral artery occlusive disease has changed substantially in the last few years. Recent technical developments such as the introduction of new image reconstruction algorithms and dedicated contrast agents have pushed the limits of MR angiography toward higher spatial resolution and image quality and have enabled time-resolved imaging. This article discusses various techniques of peripheral MR angiography, including step-by-step, hybrid, continuous table movement, and non-contrast-enhanced MR angiography.
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There seems to be an association between exposure to intravenous gadolinium-based contrast agents (GBCAs) and nephrogenic systemic fibrosis (NSF), a debilitating and sometimes fatal disease. This article addresses the relationship between GBCAs and NSF and answers some common questions. The policy deployed at Yale-New Haven Hospital for prevention of NSF and screening for patients at risk is delineated and discussed along with recommendations by the Food and Drug Administration.
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Magn Reson Imaging Clin N Am · Feb 2009
Neuroradiologic applications of dynamic MR angiography at 3 T.
Four-dimensional time-resolved MR angiography (4D-MRA) using keyhole imaging techniques is a new method of performing contrastenhanced vascular imaging. Combining parallel imaging and keyhole imaging techniques, it is possible to obtain dynamic MRA scans up to 60 times faster, thereby achieving subsecond sampling of the contrast hemodynamics. Furthermore, imaging at 3 T gives higher signal, thus affording higher spatial resolution and allowing dynamic 3D MRA to approach the diagnostic performance of conventional digital subtraction angiography. This article presents the authors' clinical experience using 4D-MRA to evaluate various vascular abnormalities in the brain, spine, orbits, and neck at 3 T, demonstrates the imaging findings of this novel technique, and discusses its advantages and use in current neuroradiology practice.
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Gadolinium-based contrast agents were for many years considered safe, but this is no longer the case. The least stable agents may trigger the development of nephrogenic systemic fibrosis (NSF), a generalized fibrotic disorder, in renal failure patients. The use of gadodiamide and gadopentetate dimeglumine is now contraindicated in Europe and Japan in patients who have a glomerular filtration rate less than 30 mL/min/1.73 m(2), including those on dialysis. The fear of NSF, however, should not lead to an enhanced MR imaging examination being denied when there is a good clinical indication to give a gadolinium-based contrast agent.
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This article describes the considerable technical achievements that have been made in MR imaging in the evaluation of pediatric patients. The latest techniques in improving signal intensity, resolution, and speed are discussed. The multitude of new options for pediatric MR imaging are illustrated, including higher field strength imaging, multi-channel coil technology coupled with parallel imaging, and new pulse sequence designs. Several future directions in the field of pediatric body and musculoskeletal imaging also are highlighted.