Estimation of Chronic Subdural Hematoma Size Using CT Imaging; a Comparison of In-Plane Thickness to 3D Volumetry

Backgrounds: Preand postoperative chronic subdural hematoma (CSDH) sizes have been used in clinical trials to predict the risk of postoperative recurrence. Commonly, dimensions of the preand postoperative lesions have been assessed by computerized tomography (CT) scans using maximum thickness as a linear measurement. Our goal was to characterize this common method for quantification of preand postoperative lesion sizes and to assess its estimation validity compared to estimation by hematoma volumetry. Methods: We prospectively investigated preand 1 postoperative day CT scans of 107 adult surgical patients with unior bilateral CSDH. Preand postoperative thickness of CSDH was determined and then compared to preand postoperative lesion volume measured with 3D hematoma volumetry. Results: Pearson correlation coefficients between mean preand postoperative lesion thickness and mean preand postoperative lesion volume in the unilateral subgroup were 0.491 and 0.498, respectively; in the bilateral subgroup 0.505 and 0.579, respectively; and in the whole series 0.653 and 0.472, respectively. Conclusions: Preand postoperative thickness of CSDH does not offer reasonable approximations of the preand postoperative lesion size when compared with results from 3D volumetry in the unilateral subgroup, bilateral subgroup or overall.