Magnitude of Hematoma Volume Measurement Error in Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE Limiting intracerebral hemorrhage (ICH) and intraventricular hemorrhage (IVH) expansion is a common target for acute ICH studies and, therefore, accurate measurement of hematoma volumes is required. We investigated the amount of hematoma volume difference between computed tomography scans that can be considered as measurement error. METHODS Five raters performed baseline (<6 hours) and 24-hour total hematoma (ICH+IVH) computer-assisted volumetric analysis from 40 selected ICH patients from the Predicting Hematoma Growth and Outcome in Intracerebral Hemorrhage Using Contrast Bolus CT (PREDICT) study cohort twice. Estimates of intrarater and interrater reliability are expressed as intraclass correlation coefficients and minimum detectable difference (MDD). RESULTS Total hematoma volumetric analyses had excellent intra- and interrater agreements (intraclass correlation coefficients 0.994 and 0.992, respectively). MDD for intra- and interrater volumes was 6.68 and 7.72 mL, respectively, and were higher the larger total hematoma volume was and in patients with subarachnoid hemorrhage or IVH. MDD for total hematoma volume measurement of 10.4 mL was found in patients with largest hematoma volumes. In patients with subarachnoid hemorrhage or IVH, MDD for total hematoma volume was 10.3 and 10.4 mL, respectively. In patients without IVH, MDD for intra- and interrater pure ICH volumes were 3.82 and 5.83 mL, respectively. CONCLUSIONS A threshold higher than 10.4 mL seems to be reliable to avoid error of total hematoma volume measurement in a broad range of patients. An absolute ICH volume increase of >6 mL, commonly used as outcome in ICH studies, seems well above MDD and, therefore, could be used to reliably detect ICH expansion.