Brief Reports Quantification of Cerebral Volumes on MRI 6 Months After Aneurysmal Subarachnoid Hemorrhage

Background and Purpose—MRI can be used to assess structural damage to the brain after aneurysmal subarachnoid hemorrhage. We tuned, validated, and applied k-Nearest Neighbor-based segmentation to quantify cerebral volumes on MRI 6 months after aneurysmal subarachnoid hemorrhage. Methods—After tuning, the accuracy of k-Nearest Neighbor-based segmentation was assessed with manual segmentations. Next, supratentorial cerebral parenchymal, peripheral cerebrospinal fluid, and lateral ventricular volumes of 55 patients were compared with those of 25 ageand sex-matched control subjects and related to clinical outcome (modified Rankin Scale). Results—k-Nearest Neighbor-based segmentation showed good agreement with manual segmentations. Compared with control subjects, patients had a larger lateral ventricular volume (difference: log-transformed values 0.54; 95% CI,0.33–0.75), smaller peripheral cerebrospinal fluid volume ( 26 mL; 95% CI, 40 to 11), and similar cerebral parenchymal volume (2 mL; 95% CI, 10 to 15). In patients, parenchymal (median split; OR, 38.8; 95% CI, 4.6–329.0) and ventricular volumes (7.4; 95% CI, 1.6–33.5) correlated with functional outcome. Conclusions—k-Nearest Neighbor-based segmentation provides accurate cerebral volume measurements after aneurysmal subarachnoid hemorrhage. In this proof-of-principle study of this volumetric technique, we demonstrated volume changes relative to controls, which correlated with functional outcome. (Stroke. 2012;43:2782-2784.)