Neuroimaging clinics of North America
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Magnetic resonance (MR) imaging at 3 T has proved superior to 1.5 T in the brain for detecting numerous pathologic entities including hemosiderin, tiny metastases, subtle demyelinating plaques, active demyelinating plaques, and some epileptogenic foci, as well as small aneurysms with MR angiography. 3 T is superior to most advanced imaging techniques including diffusion, diffusion tensor imaging, perfusion, spectroscopy and functional MR imaging. The increased signal/noise ratio at 3 T permits higher spatial resolution. Initially spine imaging at 3 T proved more difficult with less successful results. During the past 7 years, technological advances in magnet and surface coil design as well as improved radio frequency transmitters and pulse sequence design in combination with the large body of knowledge accrued by radiologists and physicists during a nine year experience with clinical imaging of the spine with the doubled B0, has resulted in 3 T MRI of the spine achieving a reputation similar to that for brain imaging.
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Diagnostic modalities for the diagnosis of acute stroke have increased in number and quality. Magnetic resonance imaging has increasingly become a central tool for the management of patients with stroke. ⋯ Recent additional sequences allow perfusion without contrast and susceptibility-weighted imaging can help identify early bleeding. These new techniques should provide more information about the on going ischemic process.
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Epileptogenic lesions are often subtle, do not change during life, and are easily overlooked, if spatial resolution and signal to noise ratio are inappropriate. 2D or more recently 3D-FLAIR sequences are best suited to detect small cortical dysplasias which are often located at the bottom of a sulcus. 3D-T1-weighted gradient echo sequences are used for multiplanar, curved surface reformations, and voxel-based analyses. 3 T MR imaging is currently the state-of-the-art imaging modality for patients with suspected structural epilepsies in which an epileptogenic lesion has not yet been found.
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Manifestations of atherosclerotic plaque in different arterial beds range from perfusion deficits to overt ischemia such as stroke and myocardial infarction. Atherosclerotic plaque composition is associated with its propensity to rupture and cause vascular events. ⋯ Plaque MR imaging at higher field strengths offers both opportunities and challenges to improving the high spatial resolution and contrast required for this type of imaging. This article summarizes the technological requirements required for high-field plaque MR imaging and its application in detecting plaque components.
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Neuroimaging Clin. N. Am. · May 2012
ReviewHead and neck high-field imaging: oncology applications.
Head and neck imaging has benefited from 1.5 T magnetic resonance (MR) imaging, providing faster sequences, better soft tissue evaluation, and 3-axis imaging, with less radiation and iodine-based contrast injection. The US Food and Drug Administration has approved human MR imaging at high-field strength up to 4 T in clinical practice. 3 T MR imaging has become widely available, with the hope of significant advance in the evaluation of the head and neck region. This article reviews the benefits, disadvantages, and challenges of high-field imaging of the head and neck region, focusing on the imaging of head and neck cancer.