Evolution of cerebral microbleeds after cranial irradiation in medulloblastoma patients

OBJECTIVE:To characterize the temporal and spatial pattern of cerebral microbleeds (CMBs) after cranial irradiation in patients with medulloblastoma. METHODS:We retrospectively identified patients with medulloblastoma treated with craniospinal irradiation at the Massachusetts General Hospital between 1999 and 2015. Longitudinal MRI including T2*-weighted gradient-recalled echo (GRE) sequences were reviewed, and the prevalence, spatial pattern, and risk factors associated with CMBs were characterized. RESULTS:We identified a total of 27 patients; 5 patients were children (median age 6.3 years) and 22 patients were adults (median age 28.8 years). CMBs were found in 67% (18/27) of patients, who were followed for a median of 4.1 years. Patients with CMBs had longer GRE follow-up time compared to those without CMBs (4.9 vs 1.7 years, p = 0.035). The median latency of the appearance of CMBs was 2.79 years (interquartile range 1.76–4.26). The prevalence of CMBs increased with each year from time of radiation therapy, and the cumulative prevalence was highest in patients age