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Abstract

Objectives: Vessel size imaging is a novel technique to evaluate pathological changes of the microvessel density quantity Q and the mean vessel size index (VSI). As a follow-up study, we assessed these parameters for microscopic description of ischemic penumbra and their potentials in predicting lesion growth. Methods: Seventy-five patients with a perfusion-diffusion mismatch were examined within 24 h from symptom onset. We defined three regions of interest: the initial infarct (INF), the ischemic penumbra (IPE), and the healthy region (HEA) symmetric to the IPE. For 23 patients with a 6th-day follow-up, IPE regions were divided into areas of infarct growth and areas of oligemia. Result: The median values of Q and VSI were: for INF 0.29 s-1/3 and 15.8 µm, for IPE 0.33 s-1/3 and 20.6 µm and for HEA 0.36 s-1/3 and 17.4 µm. The Q in the IPE was significantly smaller than in HEA, and VSI was significantly larger. The Q with a threshold of 0.32 s-1/3 predicted the final infarction with a sensitivity of 69% and a specificity of 64%. Conclusions: The reduced Q and increased VSI in the IPE confirmed our previous pilot results. Although Q showed a trend to identify the severity of ischemia in an overall voxel population, its potential in predicting infarct growth needs to be further tested in a larger cohort including a clear status of reperfusion and recanalization.