Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · Aug 2006
ReviewVasospasm in aneurysmal subarachnoid hemorrhage: diagnosis, prevention, and management.
Cerebral vasospasm is a major cause of morbidity and mortality associated with subarachnoid hemorrhage (SAH). Advances in neuroimaging and development of newer intraparenchymal monitoring devices have improved the prediction and diagnosis of cerebral vasospasm significantly. Recent experimental and clinical trials have increased the armamentarium of preventive and treatment strategies for cerebral vasospasm. ⋯ Although vasospasm usually does not recur after PTA, recurrence is frequent after vasodilator infusion. The development of newer microballoon catheters has led to improvements in treatment of not only proximal but also distal vessel vasospasm with balloon angioplasty. This article reports on current knowledge in the diagnosis, prediction, prevention, and management of cerebral vasospasm.
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Neuroimaging Clin. N. Am. · Aug 2006
ReviewRuptured intracranial aneurysms - clinical aspects of subarachnoid hemorrhage management and the International Subarachnoid Aneurysm Trial.
The last 14 years has seen a revolution in the management of intracranial aneurysms; endovascular coil treatment has moved from a minority marginal treatment applicable to a few patients in a few centers to become the mainstay of treatment of ruptured intracranial aneurysms. This article highlights new information learned from the International Subarachnoid Aneurysm Trial.
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Neuroimaging Clin. N. Am. · May 2006
Review Comparative StudyComparison of 3.0 T versus 1.5 T MR: imaging of the spine.
3 T MR imaging brings with it the possibility of a doubled signal-to-noise ratio compared with 1.5 T systems and the possibility of decreased scan times without reduction in quality. Higher cost and other issues however, also need to be examined.
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Neuroimaging Clin. N. Am. · May 2006
ReviewArterial spin labeling: benefits and pitfalls of high magnetic field.
Arterial spin labeling (ASL) techniques are MR imaging methods designed to measure the endogenous perfusion signal coming from arterial blood by manipulation of its magnetization. These methods are based on the subtraction of two consecutively acquired images: one acquired after preparation of the arterial blood magnetization upstream to the area of interest, and the second without any manipulation of its arterial magnetization. The subtraction of both images provides information on the perfusion of the tissue present in the slice of interest. ⋯ Other effects related to poorer magnetic filed homogeneities and reduced T(2) relaxation times, however, will counterbalance both effects partially. In this article, the pros and cons of the use of ASL at high field are summarized, after a brief description of the major techniques used and their theoretical limitations. Finally, a summary of the few existing dedicated ASL perfusion techniques available are presented.
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Neuroimaging Clin. N. Am. · May 2006
Review Comparative StudyComparison of diffusion tensor imaging measurements at 3.0 T versus 1.5 T with and without parallel imaging.
The diffusion properties of biological tissues are independent of magnetic field strength. Field strength, however, does affect the signal-to-noise ratio (SNR) and artifacts of diffusion-weighted (DW) images, which ultimately will influence the quantitative and spatial accuracy of diffusion tensor imaging (DTI). In this article, the effects of field strength on DTI are reviewed. ⋯ The increased SNR at 3.0 T resulted in smaller variances in the estimated mean diffusivities and fractional anisotropies. As expected, the amount of echo-planar image distortion roughly doubled going from 1.5 T to 3.0 T, but was reduced by 50% when using parallel imaging. In summary, DTI studies at 3.0 T using parallel imaging will provide significantly improved DTI measurements relative to studies at 1.5 T.