Triphasic dynamic enhanced computed tomography for differentiating cholesterol and adenomatous gallbladder polyps

Background Triphasic dynamic enhanced computed tomography (CT) scans were acquired to identify cholesterol and adenomatous gallbladder (GB) polyps that were inaccurately diagnosed before surgery. Purpose To evaluate the CT findings of 1.0- to 2.0-cm GB polyps for differentiating between cholesterol and adenomatous polyps. Methods Fifty-two patients with GB polyps were treated surgically from December 2017 to July 2020 and were retrospectively divided into 2 groups according to the postoperative pathologic results: a cholesterol group with 30 patients and an adenomatous group with 22 patients. Unenhanced and triphasic dynamic enhanced CT scans were performed for all the patients within 2 weeks before surgery. The CT image parameters were measured and analyzed by 2 senior radiologists blinded to the pathological diagnoses. Results Of the 22 patients in the adenomatous group, 77.3% were female and 22.7% were male, with a mean age of 53.5 years; among the 30 patients in the cholesterol group, 66.7% were female and 33.3% were male, with a median age of 50.1 years. The CT image parameters of all 52 patients with GB polyps were analyzed. Significant differences were found in the arterial phase CT values, portal venous phase CT values, delayed phase CT values, ∆CT1 values (portal venous phase CT minus delayed phase CT values), and ∆CT2 values (arterial phase CT minus delayed phase CT values) between the cholesterol and adenomatous polyp groups ( p < 0.05). In differentiating the two groups, the ∆CT1 and ∆CT2 values were superior to the arterial, portal venous and delayed phase CT values regarding both sensitivity and specificity. Conclusion The arterial phase CT values, portal venous phase CT values, delayed phase CT values, and ∆CT values (including ∆CT1 and ∆CT2) from triphasic dynamic enhanced CT scans can differentiate the nature of gallbladder polypoid lesions, with the ∆CT values having the highest sensitivity and specificity.