Reliability of ABC/2 Method in Measuring of Infarct Volume in Magnetic Resonance Diffusion-Weighted Image

AIMS: Manual planimetry is the current method defining infarct volume on magnetic resonance (MR) diffusion-weighted image. ABC/2 method is an ellipsoid geometric formula with advantage estimation of intraparenchymal hemorrhage volume. Our study aimed to find the reliability and reproducibility of ABC/2 method compared to manual planimetric segmentation method. SETTINGS AND DESIGN: This was a cross-sectional analytical study with retrospective and prospective data collection. SUBJECTS AND METHODS: A total of 109 patients with acute ischemic stroke and underwent MR images at Ramathibodi Hospital were retrospectively reviewed. Relationship between manual planimetric segmentation and ABC/2 methods (nonadjusted ABC/2 method and adjusted ABC*/2 method) was determined using Wilcoxon signed-rank test, linear regression analysis, and Bland–Altman plot. Subgroup analysis by location, onset, shape, and size of infarct volume was performed. Interobserver reliability was established using intraclass correlation coefficient and Bland–Altman plot. STATISTICAL ANALYSIS USED: Wilcoxon signed-rank test, linear regression analysis, and Bland–Altman plot were used for statistical analysis. RESULTS: Infarct volume measured with nonadjusted ABC/2 method (23.56, 48.81, 4.25, 0.11, 318.94) (mean, standard deviation, median, minimum, maximum) and adjusted ABC*/2 method (13.37, 28.3, 2.08, 0.06, 170.10) was smaller than manual planimetric method (28.50, 58.64, 5.56, 0.27, 335.49) (P < 0.001). Linear regression's slope confirmed underestimation of volume infarct. In round-to-ellipsoid shape and white matter group, the differences found between nonadjusted ABC/2 and manual planimetric methods are not statistically significant. CONCLUSIONS: ABC/2 method is a simple, rapid, and reproducible method with an excellent positive correlation of both adjusted and nonadjusted ABC/2 methods to manual planimetric segmentation method but tendency to underestimated infarct volume. High interobserver reliability and good agreement between two observers have been established. The utilization of nonadjusted ABC/2 method should be used with caution due to its tendency to underestimate the infarct volume.