In‐Room Direct Nidal Flow Measurement by Digital Subtraction Angiography to Estimate Hemorrhage Risk in Brain Arteriovenous Malformations: A Pilot Study

BACKGROUND Noninvasive direct flow measurement from digital subtraction angiography (DSA) is challenging in brain arteriovenous malformations (BAVMs). We devised a method to estimate the blood volume flow rate of BAVM nidus using DSA, and assessed its association with angioarchitecture features in hemorrhagic presentation. METHODS A total of 24 patients with BAVMs (10 controls and 14 with hemorrhage) who underwent DSA and magnetic resonance (MR) were retrospectively recruited. Fifteen patients underwent additional phase contrast MR imaging. The nidus volume was contoured on the MR time‐of‐flight data set. From DSA, flow velocities and volume flow rate were estimated along calibrated vascular center lines. The BAVM nidus volume flow rate was computed by adding feeding volume flow rate of arteries confirmed on DSA and then normalizing them with nidus volume to yield the nidus flow index. The correspondent phase‐contrast MR‐estimated nidus flow index was evaluated in each BAVM for comparison. Comparisons of hemodynamic parameters of the control and hemorrhage groups were conducted using the Wilcoxon rank sum test. A support vector machine was used for classifying BAVM patients using angioarchitectures and the nidus flow index. RESULTS For the DSA results, the nidus flow index was higher in the hemorrhagic group than in the control group ( P =0.0272). The flow index determined using phase‐contrast MR and nidus volume were not significant. The classification accuracy was higher when the DSA nidus flow index was added into angioarchitecture. CONCLUSION The BAVM nidus flow index can be directly estimated from DSA and may be associated with hemorrhagic BAVM. Peritherapeutic hemodynamic assessment of BAVMs inside the angio‐suite is feasible.