Determining the anatomical origin of canine hepatic masses by CT.

OBJECTIVES: To identify CT features of canine hepatic masses that could be used to determine their divisional or lobar origin.

MATERIALS AND METHODS: Preoperative, postcontrast CT images of 57 surgically resected hepatic masses were reviewed with respect to their size, position relative to the midline, gallbladder and portal vein, nearest recognisable hepatic lobar vein or portal vein and point of contact with the diaphragm and displacement of adjacent organs.

RESULTS: The most prevalent histological diagnoses were hepatocellular carcinoma (n=26; 46%) and adenoma (n=10; 18%). Based on surgical assessment, it was observed that masses originated in the left hepatic division in 30 (53%) instances, central division in seven (12%) and right division in 20 (35%). All masses to the left of midline were left divisional, but only 18/30 (60%) masses to the right of midline were right divisional. Most (26/31; 84%) masses to the left of the gallbladder were left divisional and 84% (16/19) masses to the right of the gallbladder were right divisional. Half (10/20; 50%) of the right-divisional masses were medial, lateral or dorsal to the portal vein, but all other hepatic masses were ventral to the portal vein. A hepatic lobar vein or portal vein branch adjacent to the mass was observed in 53 (93%) instances; this feature correlated with surgical assessment of the affected division in 53 (93%) hepatic masses and the affected lobe in 32 (56%).

CLINICAL SIGNIFICANCE: Combining CT features of hepatic masses appears to be an accurate method for determining their divisional or lobar origin.