CT differentiation of 1–2-cm gallbladder polyps: benign vs malignant

To evaluate MDCT findings of 1–2-cm sized gallbladder (GB) polyps for differentiation between benign and malignant polyps.

Institutional review board approval was obtained, and informed consent was waived. Portal venous phase CT scans of 1–2-cm sized GB polyps caused by various pathologic conditions were retrospectively reviewed by two blinded observers. Among the 36 patients identified, 21 had benign polyps with the remaining 15 having malignant polyps. Size, margin, and shape of GB polyps were evaluated. Attenuation values of the polyps, including mean attenuation, maximum attenuation, and standard deviation, were recorded. As determined by visual inspection, the degree of polyp enhancement was evaluated. Using these CT findings, each of the two radiologists assessed and recorded individual diagnostic confidence for differentiating benign versus malignant polyps on a 5-point scale. The diagnostic performance of CT was evaluated using a receiver operating characteristic curve analysis.

There was no significant difference in size between benign and malignant GB polyps. Ill-defined margin and sessile morphology were significantly associated with malignant polyp. There was a significant difference in mean and maximum attenuation values between benign and malignant GB polyps. Mean standard deviation value of malignant polyps was significantly higher than that of benign polyps. All malignant polyps showed either hyperenhancement or marked hyperenhancement. A _z value for the diagnosis of malignant GB polyps was 0.905.

Margin, shape, and enhancement degree are helpful in differentiating between benign and malignant polyps of 1–2-cm sizes.