Journal of neuroimaging : official journal of the American Society of Neuroimaging
-
Power motion mode Doppler (PMD) simultaneously displays flow signal intensity and direction over several centimeters of intracranial space. Insonation protocol for PMD and spectral transcranial Doppler (TCD) with typical PMD flow signatures is described in serial patients with acute stroke symptoms examined via conventional windows with a PMD/TCD unit. ⋯ PMD is a window-finding tool and a guide for spectral TCD gate placement. PMD facilitates flow detection in the M2 branches and the distal basilar artery. PMD can demonstrate recanalization of the entire MCA main stem and proximal branches, increase the yield of embolus detection and procedure monitoring, and facilitate abnormal flow pattern recognition.
-
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.
-
Duplex scanning is an accepted method for noninvasive evaluation of carotid stenosis. However, the ultrasound criteria used for the detection of threshold stenoses vary widely between laboratories, and quality assurance measures to allow adjustment of criteria are often lacking. This study was completed using receiver operating characteristic (ROC) analysis to determine Doppler velocity criteria for threshold carotid stenoses, compared to an accepted standard, and to demonstrate methods to allow adjustment of criteria. ⋯ This study showed that duplex scanning is able to detect threshold carotid stenoses. For the best performance, each laboratory should have its own criteria; however, the criteria provided here could be a helpful reference to those laboratories that have not yet established their own criteria. Most important, this study provides an example of how to evaluate the performance criteria, how to modify them, how such changes can affect performance, and how performance can be modified depending on the goals of the laboratory.
-
A persistent trigeminal artery (PTA) has been found in a number of cerebrovascular diseases. A 73-year-old asymptomatic woman was noted to have a left PTA and left subclavian steal by catheter angiography. Carotid duplex revealed a peak systolic flow velocity of 294 cm/s in the internal carotid artery (ICA) and an ICA to common carotid artery ratio > 4, suggestive of a high-grade stenosis. ⋯ Transcranial Doppler found an alternating flow pattern in the basilar artery (mean flow velocity [MFV] = 18 cm/s) and left vertebral artery (MFV = 43 cm/s). During brachial hyperemia, the MFV increased by 178% in the basilar artery and 102% in the left vertebral artery. The data suggest that a PTA may compensate for subclavian steal and may have a protective hemodynamic role in this setting.