Neuroimaging clinics of North America
-
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.
-
Neuroimaging Clin. N. Am. · May 2012
ReviewUltrahigh-field magnetic resonance imaging: the clinical potential for anatomy, pathogenesis, diagnosis and treatment planning in neck and spine disease.
An increase of the magnetic field strength to ultrahigh-field yields advantageous as well as disadvantageous changes in physical effects. The beneficial increase in signal/noise ratio can be leveraged into higher spatiotemporal resolution, and an exacerbation of artifacts can impede ultrahigh-field imaging. With the successful introduction of intracranial and musculoskeletal imaging at 7 T, recent advances in coil design have created opportunities for further applications of ultrahigh-field magnetic resonance (MR) imaging in other parts of the body. Initial studies in 7 T neck and spine MR imaging have revealed promising insights and new challenges, demanding further research and methodological optimization.
-
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.
-
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.
-
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.