CT evaluation of small polypoid lesions of the gallbladder.

Objective: The ability of CT to differentiate small polypoid lesions of the gallbladder was evaluated.

Methods: CT followed by cholecystectomy was performed in 20 patients with small polypoid lesions (< or = 20mm) of the gallbladder measured by preoperative ultrasonography. Detectability of the lesions on both unenhanced and enhanced CT, and the configuration and density of the polypoid lesions on enhanced CT were evaluated in comparison with histopathology.

Results: Unenhanced CT detected 8 of 20 polypoid lesions (40%), whereas enhanced CT detected all lesions. All the cholesterol polyp (n = 9) and hyperplastic polyp (n = 2) were not detected on unenhanced CT. Configurations of the polypoid lesions were classified into three types; pedunculated, sessile, and mass forming type. All of cholesterol polyp and hyperplastic polyp were demonstrated as pedunculated type, and adenomyomatosis (n = 2) as mass forming type in all lesions, respectively. Two of adenoma were seen as pedunculated type in one and as mass forming type in the other. Adenocarcinoma (n = 5) was depicted as sessile type in four lesions and as pedunculated type in one. The density of the lesions compared with the liver parenchyma on enhanced CT was not specific.

Conclusions: The configuration of polypoid lesions depicted on enhanced CT and visualization of them on unenhanced CT are helpful in differentiating neoplastic lesions which should be resected from other benign lesions.