Cerebral perfusion in the acute ischemic stroke: clinical and CT-perfusion assessment

Abstract

Assessment of cerebral perfusion in patients with acute ischemic stroke by means of perfusion CT (PCT) allows retrieving quantitative data on the cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Thirty patients at earliest stages (first 24 hrs) of ischemic supratentorial stroke were studied, of whom patients with moderate to severe stroke predominated (median NIHSS score of 11.5). PCT was performed on day 1, 3 and 10, and diffusion-weight ed MRI (DWI) on day 1. It was shown that cerebral ischemia in the acute stage was characterized by the decrease of CBF and CBV (10.0 ml/100g х min and 1.9 ml/100 g, respectively), and the increase of MTT (11.3 s). CBV lesion correlates well with the DWI lesion (r=0.91), i.e. with irreversible ischemic tissue damage, and its size is smaller than the sizes of CBF and MTT lesions. This mismatch reflects the “penumbra” zone. The infarct “core” has decreased CBF and CBV, and elevated MTT, while the “penumbral” tissue has only decreased CBF and elevated MTT when compared to the normal hemisphere. The “penumbra” and the “core” differ by values of CBF and CBV, but this difference is shaded by day 3. Increase of CBV in the infarct “core” in the course of stroke indicates the restoration of blood flow. A prognostic index is elaborated which allows predicting the transformation of ischemia into irreversible tissue damage: it is the decrease of CBV for more than 12% copared with the intact hemisphere.