Indications for reconstruction after hyper-acute stroke using perfusion CT

We performed perfusion computed tomography (PCT) in patients with hyper-acute stroke to evaluate its usefulness for the indication of percutaneous transluminal revascularization. The subjects were 21 patients with stroke in the carotid system admitted within a few hours of onset when no ischemic change could be detected by the initial CT but was already present as confirmed by PCT parameters of either mean transit time (MTT), cerebral blood flow (CBF) or cerebral blood volume (CBV). Percutaneous transluminal revascularization was performed in all patients at the earliest possible opportunity. The CBF and CBV values were calculated in regions of interest (ROIs) selected in the ischemic lesion, and compared with the same location on the opposite side (ROI ratio). Patients with visual decreases in CBF and CBV as well as delay of MTT suffered severe infarction. Patients with only delay of MTT were saved from extensive infarction by the reperfusion treatment. Some patients with ischemia visually identified by both MTT and CBF suffered severe infarction, but others only had localized infarction. The ROI ratio of the CBV was increased in these patients with localized infarction but decreased in the patients with severe infarction. The mean ROI ratios associated with subsequent infarction were 0.438±0.276 (mean±SD) for CBF and 0.873±0.290 for CBV, and those associated with no subsequent infarction were 0.862±0.429 for CBF and 1.289±0.486 for CBV. Delay of MTT indicates reconstruction whereas decreased CBV carries no indication. The decision-making is difficult in patients in whom visual evaluation cannot confirm decreased CBF. In such cases, the ROI ratio of CBV must be measured if any decrease in CBF is suspected. (author)