Tissue at risk is overestimated in perfusion-weighted imaging: MR imaging in acute stroke patients without vessel recanalization.

Background And Purpose: The volume of decreased cerebral blood flow (CBF) in acute stroke perfusion-weighted imaging frequently overestimates final infarct volume. We hypothesized that surviving tissue exists even in patients without recanalization and tried to determine perfusion thresholds from initial MR imaging.

Methods: Stroke MR imaging including MR angiography was carried out at days 0, 1, and 7 after stroke onset in 19 patients without recanalization at least until day 1.

Cerebral perfusion impairment correlates with the decrease of CT density in acute ischaemic stroke.

Within the first 6 h of ischaemic stroke, changes on computed tomography (CT) scans are known as early ischaemic signs. We tested the hypothesis that the severity of perfusion impairment correlates with the degree of CT density decrease. Water uptake in ischaemic brain tissue results in a subtle decrease of CT density, and was quantified by delineation of the corresponding decrease of the apparent diffusion coefficient (ADC).