Background: Intracerebral hemorrhage (ICH) volumes are frequently used for prognostication and inclusion of patients in clinical trials. There are three commonly used methods for volume estimation: the original ABC/2 method a simplified version (sABC/2), and the planimetric method. We sought to compare the ABC/2 and sABC/2 methods with the planimetric method.
Methods: We retrospectively reviewed admission CT scans of consecutive ICH patients admitted to a single academic center from July 2012 to April 2013. Only patients with spontaneous ICH were included. We assessed ICH volume on the admission CT. In the ABC/2 method, C is the number of approximate cuts the hemorrhage is seen on (weighted by area as 75%), while in the sABC/2 method, C is the total number of cuts in which the ICH is seen. Planimetric analysis was performed with the Analyze software. Band-Altman plots were generated for both the ABC/2 and sABC/2 methods in comparison to the planimetric method; all units were log transformed.
Results: 135 patients with spontaneous ICH were included in the final analysis. Band-Altman analysis illustrated that both ABC/2 and sABC/2 were concordant with the planimetric method. ABC/2 had more bias than sABC/2 (47% vs 5%, respectively) with no evidence of a linear trend. At a lower volume threshold of 30 mL, ABC/2 was less sensitive but more specific than sABC/2 (sensitivity 77.9% and specificity 98.9% vs sensitivity 93.3% and specificity 91.1%, respectively, p<.0001). Overall, sABC/2 performed better than ABC/2 (c-stat 0.92 vs 0.88, respectively).
Conclusion: Simplified ABC/2 (sABC/2) method performs better than ABC/2 in differentiating volumes greater than 30 ml. Both ABC/2 and sABC/2 methods accurately measure hematoma volumes in spontaneous ICH patients, in comparison with the planimetric method. These findings may have implications for outcomes prediction and clinical trials inclusion.