Brain V12 Predicts Radiation-Induced Adverse Events and Late Complications After Stereotactic Radiosurgery for Brain...

Stereotactic radiosurgery (SRS) is an effective treatment for brain arteriovenous malformations (AVMs), though radiation-induced adverse events (RAEs)-including peri-nidal T2 signal changes and late radiation-induced complications (LRICs)-remain concerns. We evaluated whether brain V12 (volume of surrounding brain receiving ≥12 Gy) predicts RAEs, including chronic encapsulated hematoma and cyst formation.

We retrospectively reviewed 317 patients who underwent SRS at a single institution between 1998 and 2020. Large AVMs with a nidus volume ≥10 mL were excluded. The primary outcome was the incidence of RAEs. Predictors of RAEs were identified using Cox proportional hazards models. Secondary outcomes included AVM obliteration and post-SRS hemorrhage. The optimal brain V12 cutoff for predicting symptomatic RAEs at 60 months post-SRS was identified using receiver operating characteristic analysis.

The cohort included 176 males (56%), and 137 patients (43%) had prior hemorrhage. Median follow-up was 68 months (interquartile range [IQR], 30-133). Peri-nidal T2 signal changes occurred in 149 patients (47%), including 129 (41%) transient and 20 (6%) permanent. Brain V12 was significantly associated with both transient (hazard ratio [HR], 1.09; 95% confidence interval [CI], 1.04-1.13; P < .01) and permanent (HR, 1.15; 95% CI, 1.07-1.24; P < .01) T2 changes. LRICs occurred in 15 patients (5%) at a median of 92 months (IQR, 59-140) and were more common in those with permanent T2 changes (40% vs 5%, P < .01) and higher brain V12 (median 3.44 vs 2.78 mL, P = .04). Brain V12 was an independent predictor of symptomatic RAEs (HR, 1.21; 95% CI, 1.14-1.28, P < .01), with an interpretable reference of 4.5 mL. Five-year cumulative AVM obliteration rate was 89%, and post-SRS hemorrhage rate was 4 per 1000 patient-years.

Brain V12 is a strong predictor of peri-nidal T2 signal changes, LRICs, and symptomatic RAEs. Limiting brain V12 may reduce complications while maintaining treatment efficacy.