Three-dimensional cluster spread of post-CTA delayed hyperdensity predicts hematoma expansion in spontaneous intracerebral hemorrhage

Background and purpose Hematoma expansion (HE) after spontaneous intracerebral hemorrhage (ICH) worsens clinical outcomes. Post-computed tomography angiography (post-CTA) delayed hyperdensity within the hematoma (Hu_pcCT98) reflects contrast pooling, but whether the spatial dispersion of hyperdense clusters provides additional prognostic information beyond positivity alone is unclear. Methods This single-center retrospective cohort study (Chongqing University Three Gorges Hospital, 2021–2023) included 403 patients with acute primary ICH and evaluable post-CTA delayed axial imaging. Hu_pcCT98 positivity was defined as at least one voxel with Hounsfield units (HUs) ≥ 98 within the baseline ICH region of interest. Among the 128 Hu_pcCT98-positive patients, 13 prespecified spatial metrics and clinical covariates were evaluated for their association with HE (>6 mL or >33% ICH growth on follow-up non-contrast CT within 36 h). A prespecified screening pipeline with collinearity control selected cluster_spread_3d (maximum normalized inter-centroid distance among Hu_pcCT98 clusters) for multivariable logistic regression models. Results HE occurred in 52 of the 128 Hu_pcCT98-positive patients (40.6%) compared with 12 of the 275 Hu_pcCT98-negative patients (4.4%; odds ratio [OR], 15.0; 95% confidence interval (CI), 7.6–29.5; p < 0.001). After adjusting for clinical and imaging covariates, higher cluster_spread_3d was independently associated with HE (adjusted odds ratio per 1-unit increase, 7.27; 95% confidence interval, 1.79–29.45; p = 0.005). The cross-validated area under the receiver operating characteristic curve was 0.69, indicating moderate discrimination. Conclusion Among Hu_pcCT98-positive patients, greater three-dimensional (3D) spread of hyperdense clusters was independently associated with HE. Automated spatial quantification of post-CTA contrast pooling may complement existing markers and warrants external validation.