Diagnostic Utility of Triple‐Phase CT: Differentiating Benign Liver Lesions from Hepatocellular Carcinoma in Dogs

ABSTRACT This study aimed to identify triple‐phase computed tomographic features that can predict the histotype of focal liver lesions in dogs. The analysis included dogs with histopathologically diagnosed nodular hyperplasia (NH, n = 3), hepatocellular adenoma (HCA, n = 32), or hepatocellular carcinoma (HCC, n = 59). Consistent with previous studies (Kutara et al. 2014; Burti et al. 2021), significant differences were observed in maximum transverse diameter ( p = .008) and enhancement patterns ( p = .0031) among the lesion types. HCCs were significantly larger and exhibited heterogeneous enhancement compared with benign lesions. In the portal venous phase, benign lesions were significantly hyperattenuating ( p < .001) with a mean HU of 175.3 (±38.8), while HCCs were significantly hypoattenuating ( p < .001) with a mean HU of 123.9 (±28.8), relative to the surrounding liver parenchyma (mean HU 151.6 ± 17.7). In the delayed phase, benign lesions became isoattenuating (mean HU 117.2 ± 10.7) to the liver parenchyma (mean HU 122.6 ± 8.4), whereas HCCs remained hypoattenuating (mean HU 100.3 ± 12.7). A maximal transverse diameter greater than 9.8 cm (AUC = 0.73), a heterogeneous enhancement pattern in all three phases (AUC = 0.7), and a portal venous phase HU below 136 (AUC = 0.87) were significantly associated with HCC, achieving an accuracy of 89% and a positive predictive value of 91%. The study suggests that lesion HU in the portal venous phase, alongside lesion size and enhancement pattern, are strong predictors of HCC in dogs, with specific cutoff values serving as reliable indicators.