Journal of neuroimaging : official journal of the American Society of Neuroimaging
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To evaluate visualization and signal characteristics of macroscopic changes in patients with ophthalmologically stated papilledema and to find a suitable high-resolution magnetic resonance imaging (MRI) protocol. ⋯ An MRI protocol consisting of a 5-mm transverse T2w TSE sequence; a T2*w, 3D CISS sequence; a T1w, 3D MP-RAGE sequence with and without contrast medium; and a transverse T1w, (2-mm) 2D TSE sequence with fat-suppression technique with intravenous contrast medium is suitable to visualize the macroscopic changes in papilledema. In addition, this combination is an excellent technique for the examination of the orbits and the brain.
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The insonation of the posterior communicating artery (PcomA) is often hampered by the unfavorable insonation angle when the temporal acoustic bone window (TBW) is used. This problem may be ameliorated by a lateral frontal bone window (LFBW). This study evaluated the TBW and LFBW for the assessment of collateral intracranial flow conditions and aimed at defining diagnostic transcranial color-coded duplex sonography (TCCS) criteria that do not need compression maneuvers. ⋯ The LFBW proved useful as a complementary insonation plane to assess intracranial crossflow conditions, especially via the PcomA. We were able to define TCCS criteria for functional relevant collateralization without the need of compression maneuvers.
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Previous studies of transcranial Doppler (TCD) sonography in acute stroke have used the relative difference between the symptomatic and asymptomatic arteries to assess arterial occlusion. However, a simple measure of absolute mean flow velocity might provide a direct assessment of "perfusion reserve" in acute ischemic stroke. ⋯ The findings suggest that in the normal hemisphere (with intact autoregulation on the horizontal portion of the autoregulation curve), flow velocity and transit time are not closely related to each other, but in the symptomatic hemisphere (on the downward slope of the autoregulation curve), flow velocity is directly proportional to the transit time and, therefore, to its inverse, perfusion reserve. The use of absolute mean flow velocity values on TCD should be further explored as a simple way of assessing "perfusion" in acute ischemic stroke.
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Electroencephalography (EEG) is traditionally used to assess the duration of hemispheric anesthetization and to monitor return of function in the anesthetized hemisphere during the intracarotid amobarbital procedure (IAP), but EEG changes are not consistently seen. The authors evaluated the role of continuous transcranial Doppler (TCD) monitoring as an alternative to EEG. ⋯ Continuous TCD monitoring may be a more sensitive method than EEG in determining the duration of hemispheric anesthetization during IAP. Because the items for assessment of memory are presented during the period of hemispheric anesthetization, TCD may be useful in more precisely defining the time window for memory testing.
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Patients with objective evidence of memory impairment have been considered to be at risk for developing Alzheimer's disease (AD). However, little is known about patterns of regional cerebral blood flow abnormalities and their prognostic significance in these patients. ⋯ These results demonstrate that (1) subjects with an earlier onset of memory loss have an increased risk for developing AD, (2) SPECT can be useful for distinguishing subjects with memory loss who will rapidly progress to AD from those who will not, and (3) perfusion impairment typical of AD was evident even in subjects with memory impairment who remained nondemented.