Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Residual giant-cystic craniopharyngiomas are amenable to intracavitary bleomycin treatment. Radiologic identification of potential cyst leaks is of paramount for treatment decisions. ⋯ In one case, whose previous water-soluble iodinated contrast-enhanced CT cystography was negative for leaks, intracystic Gd-enhanced MR showed intraventricular Gd enhancement. We conclude that MR imaging after intracystic administration of Gd-based contrast paramagnetic agents is useful in the detection of potential leaks in cases of giant residual craniopharyngiomas.
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Real-time fMRI is especially vulnerable to task-correlated movement artifacts because statistical methods normally available in conventional analyses to remove such signals cannot be used in the context of real-time fMRI. Multi-voxel classifier-based methods, although advantageous in many respects, are particularly sensitive. Here we systematically studied various movements of the head and face to determine to what extent these can "masquerade" as signal in multi-voxel classifiers. ⋯ Movement tasks of many types (including movements of the eyes, face, and body) can lead to false positives in classifier-based real-time fMRI paradigms.
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Case Reports
Angiographic perfusion imaging: real-time assessment of endovascular treatment for cerebral vasospasm.
Cerebral perfusion analysis is useful in the diagnosis and treatment of cerebral vasospasm. A new modality of real-time cerebral perfusion imaging and analysis has been developed using standard 2-dimensional angiography. We report our initial experience with this technique to assess response to therapy during endovascular vasospasm procedures. ⋯ Real-time angiographic perfusion imaging is feasible during endovascular procedures for vasospasm. Perfusion analysis may aid in assessment of efficacy of the intervention. Comparison with traditional perfusion imaging is needed to validate this technique.
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Cerebral autoregulation (CA) enables the brain to maintain stable cerebral blood flow (CBF). CA can be assessed noninvasively by determining correlations between CBF velocity (CBFV) and spontaneous changes in blood pressure. Postrecording signal analysis methods have included both frequency- and time-domain methods. However, the test-retest reliability, cross-validation, and determination of normal values have not been adequately established. ⋯ CA parameters obtained by time- and frequency-domain methods correlate well, and show good interhemispheric and test-retest reliability. Group means from healthy controls may provide adequate norms for determining abnormal CA in cerebrovascular patients.
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Comparative Study
Natural history of acute stroke due to occlusion of the middle cerebral artery and intracranial internal carotid artery.
The natural history of acute ischemic stroke (AIS) due to anterior circulation large artery occlusion is not well established. This information is essential for assessment of clinical benefit derived from recanalization therapies. ⋯ Outcome of AIS patients with anterior circulation large artery occlusion not treated with reperfusion therapies is extremely poor in TICA and proximal MCA occlusions with better outcomes noted in distal MCA occlusions. These findings are relevant for estimation of treatment effect of reperfusion therapies according to occlusion location.