Sensitivity Comparison of Follow-up MRI Between Acute Cerebral and Cerebellar Cortical Microinfarctions ( CMI )Microinfarctions

Cerebral cortical microinfarctions (CMI) are frequently observed on MRI and histology studies, especially in elderly patients and in patients with cognitive dysfunction. The majority of these studies analysed chronic cerebral CMI lesions. The few studies reporting on temporal dynamics of MRI signal of acute cerebral CMI showed very low sensibility for persisting signal changes on follow-up MRI on standard MRI sequences. A retrospective study, analysing follow-up 3T MRI in 25 patients with acute cerebral CMI (defined as ≤10 mm on DWI), showed a chronic cerebral CMI detection rate of only 16% on T2-weighted and 5% on FLAIR imaging after a mean follow-up period of 33 months (with a very wide range of 0.5-142 months). Another 3T MRI study including seven patients showed disappearance of all acute cerebral very small-sized CMI (defined as \<5 mm size on initial DWI) on all follow-up MRI sequences (T1- and T2-weighted and FLAIR imaging, performed after one month). Recently, it has been shown that chronic relatively small (\<20 mm) cerebellar cortical infarctions (based on diffusion-weighted imaging) were frequently observed in acute stroke patients, especially in case of cardioembolic stroke (with chronic small cerebellar cortical infarctions observed in 32% of cases). The high prevalence of these chronic small cerebellar cortical infarctions suggest a possible higher detection rate of chronic small-sized infarction in the cerebellum compared to the supratentorial brain.