Longitudinal radiological follow-up of individual level non-ischemic cerebral enhancing lesions following endovascular aneurysm treatment

Background Non-ischemic cerebral enhancing (NICE) lesions following aneurysm endovascular therapy are exceptionally rare, with unknown longitudinal evolution. Objective To evaluate the radiological behavior of individual NICE lesions over time. Methods Patients included in a retrospective national multicentric inception cohort were analyzed. NICE lesions were defined, using MRI, as delayed onset punctate, nodular, or annular foci enhancements with peri-lesion edema, distributed in the vascular territory of the aneurysm treatment, with no other confounding disease. Lesion burden and the longitudinal behavior of individual lesions were assessed. Results Twenty-two patients were included, with a median initial lesion burden of 36 (IQR 17–54) on the first MRI scan. Of the 22 patients with at least one follow-up MRI scan, 16 (73%) had new lesions occurring mainly within the first 200 weeks after the date of the procedure. The median number of new lesions per MRI was 6 (IQR 2–16). Among the same 22 patients, 7 (32%) had recurrent lesions. The median persistent enhancement of a NICE lesion was 13 weeks (IQR 6–30). No factor was predictive of early regression of enhancement activity with lesion regression kinetics mainly being patient-dependent. Conclusions The behavior of individual NICE lesions was found to be highly variable with an overall patient-dependent regression velocity.