Indeterminate nodule-like arterial phase hyperenhancement in the liver on CT: differentiation of hepatocellular carcinomas from vascular pseudolesions using a CT radiomics approach.

Background: Accurate diagnosis of nodule-like arterial phase hyperenhancement (NAPH) on computed tomography (CT) is challenging but important for guiding the next steps in patient management. This study aimed to investigate the feasibility of CT radiomics for distinguishing hepatocellular carcinomas (HCCs) from vascular pseudolesions in indeterminate NAPH observations detected in HCC high-risk patients. Methods: In this retrospective study, 259 CT-detected NAPHs [<20 mm, eventually diagnosed as HCCs (n=51) or vascular pseudolesions (n=208)] from 181 patients were divided into a training set (204 NAPHs with 35 HCCs) and a validation set (55 NAPHs with 16 HCCs). A generalized estimating equation (GEE) model for differential diagnosis of HCC was built using CT arterial phase two-dimensional (2D) radiomics features of NAPHs, then a combined model was constructed by adding significant conventional imaging features. Model performances were assessed by receiver operating characteristic (ROC) curve analysis. Results: Out of 1,226 extracted radiomics features, four second-order features were chosen for building the radiomics model, which resulted in areas under the ROC curve (AUCs) of 0.794 [95% confidence interval (CI): 0.710-0.874] in the training set and 0.688 (95% CI: 0.528-0.842) in the validation set. Incorporating lesion location (subcapsular Conclusions: For indeterminate NAPHs, CT radiomics analysis on arterial phase imaging may help differentiate HCC from vascular pseudolesions, which can impact the subsequent diagnostic work-up and management strategy.