The presence of a perfusion-diffusion mismatch is a useful indicator for predicting the progression of acute cerebral infarction. However, not all the area of the perfusion-diffusion mismatch progresses to infarction and a large proportion survives with hypoperfusion. The purpose of this study was to assess 1) whether tissue viability can be predicted using quantitative perfusion values and 2) whether there is correlation between the perfusion value and the time that elapsed after the onset of symptoms.

Twenty-two patients with acute infarction in the middle cerebral artery territory within 12 hours after symptom onset were included in this study. We excluded those patients in whom thrombolysis was attempted or the lesion volume was less than 5 mL. Patients without perfusion-diffusion mismatch on the mean transit time (MTT) map were also excluded. We categorized the ischemic lesions into 3 areas: 1) the initial infarction, 2) the area that progressed to infarction, and 3) the hypoperfused but surviving area, based on the initial and follow up diffusion-weighted images and initial mean transit time (MTT) map. We obtained the relative cerebral blood volume (rCBV), the cerebral blood flow (rCBF) and the MTT in each area by comparing to the contralateral normal area. Statistical analysis was performed using one-way ANOVA to test whether there was a difference in perfusion values between each area. The threshold value was calculated between areas 2 and 3 using the receiver operating characteristics curve. We analyzed the correlation between the perfusion values of each area and the time that elapsed after the inset of symptoms.

The perfusion values among each region were significantly different on the rCBV, rCBF and MTT maps. Between regions 2 and 3, the rCBV and rCBF maps showed a significant difference (Bonferroni post hoc analysis), but in case of rCBV, the mean perfusion values in each region approached to the normal level and it was difficult to differentiate between the two regions on the rCBV map. The rCBF in the regions 1, 2 and 3 was 0.40, 0.64, and 0.84, respectively. The difference of the threshold values of the rCBF between regions 2 and 3 was 0.75. There was no significant correlation between the time that elapsed after symptom onset and the perfusion values of each region on the rCBV, rCBF and MTT map.

The perfusion values between the area of the initial infarction, the area that progressed to infarction and the hypoperfused but surviving area showed significant differences. The rCBF was the most useful parameter in differentiating between areas that progressed to infarction and the surviving areas. Quantitative measurement of the perfusion values may have a role in selecting the candidates for thrombolysis after they have suffered hyperacute stroke.