ABC/XYZ Estimates Intracerebral Hemorrhage Volume as a Percent of Total Brain Volume in Children

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Abstract
Background and Purpose— Intracerebral hemorrhage volume (ICHV) as a percentage of total brain volume (TBV) is a strong predictor of outcome in childhood intracerebral hemorrhage with ICHV/TBV >2% associated with functional impairment. We aimed to determine whether easily performed approximations of intracerebral hemorrhage and brain volume can accurately and reliably stratify intracerebral hemorrhage by size. Methods— CT scans of 18 children with spontaneous intracerebral hemorrhage were independently reviewed by 4 neurologists. ICHV as a proportion of TBV was estimated as ABC/XYZ expressed as a percentage: A= largest axial hemorrhage diameter; B=largest axial diameter perpendicular to A on the same slice; and C=hemorrhage vertical diameter. Similarly, X=largest midline axial diameter of supratentorial brain; Y=largest axial diameter perpendicular to X; and Z=brain vertical diameter. Interrater reliability was measured with intraclass correlation coefficients. ICHV and TBV were measured using computer-assisted manual segmentation tracings to establish criterion validity. Each intracerebral hemorrhage was classified as small (≤2% TBV) or large (>2% TBV). Results— Estimates of ICHV, TBV, and ICHV/TBV using the ABC/XYZ method had outstanding interrater reliability (intraclass correlation coefficient, 0.95 to 0.99). These estimates were highly correlated with volumetric measures ( R 2 =0.77 to 0.96). Sensitivity of the ABC/XYZ method for identifying an ICHV >2% TBV was 100% (95% CI, 89% to 100%). Specificity was 95% (95% CI, 83% to 99%). Conclusions— The ABC/XYZ method accurately and reliably estimates ICHV and TBV in children. These values can be used to approximate quickly and easily ICHV as a percentage of TBV, which has important prognostic implications.

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