Intracerebral hemorrhage volume estimation: Is modification of the ABC/2 formula necessary according to the hematoma shape?

Objective: We studied the proposal to modify the ABC/2 formula to ABC/3 for irregular-shaped intracerebral hematoma (ICH) volume estimation. Patients and methods: The volume of 133 ICHs were estimated with Kwak's (simplified C; all slices with hemorrhage are considered equal), Kothari's (weighted C) and coronal (reformatted C; measuring C directly on coronal reformatted images) ABC/2 methods, and compared with computer-assisted planimetric measurements. The accuracy, precision and correlation of three ABC/2 methods and their ABC/3 modifications were determined in smooth (Barras' group 1 or 2) and irregular (Barras' group 3-5) shaped ICHs. Results: As the hematoma size increases, the shape becomes irregular. In all hematomas, both smooth (n = 81) and irregular (n = 52) shaped, Kothari's ABC/2 formula provided the closest result to the planimetric measurement, with an underestimation of 1.77 mL, and 10.2% difference on average. Kothari's ABC/2 disclosed the best correlation (Lin's coefficient = 0.9622) regardless of ICH shape. When simplified-ABC/2 method was modified as ABC/3, volume estimation accuracy increased (Correlation coefficient increased from 0.838 to 0.915) for irregular hematomas; however, despite this improvement the accuracy remained below the Kothari's ABC/2 (not ABC/3) method. Neither reformatted coronal ABC/2 nor its ABC/3 modification provided any advantage over ABC/x formulas with slice counting. Conclusion: Kothari's ABC/2 method is a valid method for estimation of ICH volume for both regular and irregular shaped hematomas. Simplified (Kwak's) ABC/2 or coronal ABC/2, or their /3 counterparts do not provide additional advantage.