Objective:To investigate the predictive values of baseline hematoma mean CT value and shape regularity (SR) for hematoma enlargement (HE) in patients with spontaneous intracerebral hemorrhage (ICH).Methods:Patients with ICH admitted to Yulin First Hospital from June 2018 to December 2021 were retrospectively included. The first head CT scan was performed within 24 h of onset, and the second head CT scan was performed within 72 h of the first scan. HE was defined as an increase in hematoma volume of at least 6 ml or 33% from the first CT. 3D Slicer software was used to reconstruct 3D images and SR was calculated. Multivariate logistic regression analysis was used to determine the independent factor for HE. Receiver operator characteristic (ROC) curve was used to evaluate the predictive value of baseline hematoma mean CT value for HE. Results:A total of 249 patients with ICH were enrolled, including 134 males (53.8%), and aged 62.2±12.1 years. The median baseline Glasgow Coma Scale score was 12, and the median time from onset to first CT scan was 3.1 h. The median baseline hematoma volume was 10.9 ml, and 58 patients (23.3%) showed HE. The baseline hematoma mean CT value in the HE group (58.5±3.2 HU vs. 60.3±3.3 HU; P<0.01) and baseline SR (0.615±0.146 vs. 0.688±0.100; P<0.001) were significantly lower in the non-HE group. Multivariate logistic regression analysis showed that the time from onset to first CT scan (odds ratio [ OR] 0.867, 95% confidence interval [ CI] 0.786-0.957; P=0.004), the baseline hematoma volume ( OR 1.050, 95% CI 1.028-1.073; P<0.001), and the baseline hematoma mean CT value ( OR 0.809, 95% CI 0.725-0.902; P<0.001) were the independent predictors of HE, while the baseline SR had no significant independent correlation with HE. ROC curve analysis showed that the area under the curve of baseline hematoma mean CT value for predicting HE was 0.652 (95% CI 0.573-0.731; P<0.001), with an optimal cutoff value of 57.97 HU. The sensitivity and specificity for predicting HE were 50% and 75.9%, respectively. Conclusion:The baseline hematoma mean CT value is an independent factor for HE in patients with ICH and has certain predictive value for HE.