Improvements in the Quantitative Assessment of Cerebral Blood Volume and Flow with the Removal of Vessel Voxels from MR Perfusion Images
The postprocessing procedure from a patient with 90% left internal carotid stenosis (patient #1 in Table 2). A ratio image (a) and CSF mask (b) were obtained for CSF removal. Histograms of the rCBV (c) and the rCBF (d) after CSF removal were plotted. The median values of the rCBV and rCBF are marked with green lines. The thresholds for the preliminary vessel voxel removal were set at twice the median (red lines). Preliminary vessel masks were calculated from the rCBV image (e), rCBF image (f), and both rCBV and rCBF images (g). In (g), yellow voxels are from the rCBV mask, cyan voxels are from the rCBF mask, and red voxels are from both. More vessel voxels are identified on the stenotic side (arrows) than the normal side on rCBV mask (e). Vessel voxels on the lesion side (arrows) are not properly demonstrated on rCBF mask (f). The segmented normal perfused brain parenchyma is shown in (h).