MR perfusion studies of brain for patients with unilateral carotid stenosis or occlusion: evaluation of maps of "time to peak" and "percentage of baseline at peak".

Maps of "time to peak" (TTP) and "percentage of baseline at peak" (PBP) were compared with maps of conventional brain perfusion parameters, namely, mean transit time (MTT) and relative cerebral blood volume (rCBV). We performed MR perfusion studies in 11 patients. All of them had occlusion or high-grade stenosis of the unilateral carotid artery. Three areas of old infarct, 4 areas of new infarct, and 10 areas of brain without infarct were evaluated specifically. In all these cases, the TTP maps appeared similar to the MTT maps. They showed increases, normal values, or decreases at the same time in all areas evaluated. Most areas of abnormally decreased CBV had increased signal in PBP maps. In conclusion, the TTP map provided the same qualitative information as MTT. PBP seemed correlated inversely to CBV and was less sensitive in demonstrating abnormality.