Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · May 2012
ReviewDiffusion tensor and perfusion imaging of brain tumors in high-field MR imaging.
Diffusion tensor imaging (DTI) and perfusion-weighted imaging (PWI) are essential tools for diagnosing, differentiating, and monitoring brain tumors. High-field MRI provides higher signal-to-noise ratio, shorter scan time, and better image quality. ⋯ PWI provides reliable biomarkers for glioma grading, therapeutic responses, and differential diagnosis of various brain tumors. With higher field strength, better-quality DTI and PWI can raise the diagnostic accuracy in brain tumors.
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Neuroimaging Clin. N. Am. · May 2012
ReviewCurrent state-of-the-art 1.5 T and 3 T extracranial carotid contrast-enhanced magnetic resonance angiography.
Recent advances in magnetic resonance (MR) hardware and software have improved the resolution and spatial coverage of head and neck first-pass contrast-enhanced (CE) MR angiography. Despite these improvements, high-quality submillimeter-resolution 1.5 T and 3 T carotid CE MR angiography is not consistently available in the general radiology practice. This article reviews the important imaging parameters and potential pitfalls that affect carotid CE MR angiography image quality, and the dose and timing of the gadolinium-based contrast agent, and summarizes vendor-specific protocols for high-quality submillimeter-resolution carotid CE MR angiography at 1.5 and 3 T.
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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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High-field 3 T magnetic resonance (MR) imaging provides greater signal-to-noise ratio (SNR) compared with 1.5 T systems. Various MR imaging clinical applications in children can benefit from improvements resulting from this increased SNR. ⋯ However, challenges inherent to 3 T imaging become more relevant in children. The use of 3 T imaging in children has allowed better diagnostic efficacy in neuroimaging, but certain technique modifications may be required for optimal 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.