To quantitatively characterize the radiologic presentation of ICH-Mediated Encephalomalacia on Day 180 CTs and assess its’ relationship to clinical variables and Day 180 functional outcomes following hemorrhagic stroke in patients enrolled in the MISTIE-II trial.

MISTIE-II patients with Day 180 CTs were included (n=46). Volume segmentation was performed by 1 expert reader (HA) using a free-handed technique within the image-processing software OsiriXMD (Pixmeo). Imaging-based measurements included volume and average HU values for IME (lesion site CSF-like hypointensity), and ‘Effected’ Region' (lesion site and adjacent hypoattenuated tissue). ICH/IVH volumes were obtained with a semi-automated planimetry approach. Regression analysis defined “good” functional outcome at D180 as an mRS 0-3.

Patients with poor Day 180 functional outcomes had larger Relative IME Volumes [(IME Vol)/(Stability ICH Vol)]; 0.52-0.32 cc p=0.02), lower average IME HU values (13.3-15.8 HU p=0.02), and marginally larger IME volumes (19.4-14.3 cc, p=0.12). Univariate and multivariate logistic regression predicted a 4% and 6% decrease in the odds of good functional outcome for each unit increase in Relative IME Volume, respectively (p=0.013; p=0.025).Patients with lobar hemorrhages displayed larger ER volumes (30.0-18.9 cc, p=0.05) and near larger IME volumes (21.2-14.0 cc, p=0.06) than deep hemorrhages. Random sampling for reproducibility yielded no significant difference between expert and comparator (AG) IME/ER volumes (p=0.41).

Our results suggest Relative IME Volume to be a potentially meaningful and novel predictor of poor functional outcome after stroke. There exist clinical correlates to IME volume and further research regarding mechanisms driving accelerated or attenuated IME growth after stroke is needed.