Magnetic resonance imaging clinics of North America
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The primary advantage of high field strength MR imaging over imaging on modern 1.5 Tesla (T) systems is increased signal-to-noise ratio, which can be used to improve image quality or shorten scan acquisition time. In the years since 3.0T scanners were first approved for clinical use, one of the areas which has benefited greatly from its introduction is neurovascular MR angiography (MRA). ⋯ This article discusses the current state of neurovascular MRA at 3.0T, basic physical differences between MR imaging at 1.5T and 3.0T, and their effects on MRA sequences. The literature regarding the efficacy of 3.0T MRA techniques for diagnosing specific neurovascular pathologies and carotid steno occlusive disease is reviewed.
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Vascular pathology in children is commonplace and involves every organ system; however, the powerful, noninvasive, and rapid three-dimensional imaging capability offered by MR angiography is underutilized in children. The success of pediatric MR angiography depends on modifying the MR angiography on the basis of patient size, hemodynamic status, and clinical indications in children, and requires an adequate understanding of pediatric-specific hardware, software, and equipment requirements. This article provides an overview of general pediatric MR angiography techniques, common indications for body MR angiography in children, and the complementary role of MR angiography to other vascular imaging modalities in children, including CT angiography, Doppler ultrasound, and catheter angiography.
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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.