Differential Diagnosis of Gallbladder Wall Thickening: The Usefulness of Contrast-Enhanced Ultrasound

The purpose of this study was to evaluate the usefulness of contrast-enhanced ultrasound (CEUS) in the differential diagnosis of gallbladder wall (GBW) thickening and determine the predictors of malignant GBW thickening. One hundred fifty-nine patients with GBW thickening, including 76 men and 83 women, from eight institutions were enrolled. CEUS was performed after injection of a sulfur hexafluoride microbubble-based ultrasound contrast agent. Multiple logistic regression analysis was used to reveal independent predictors associated with malignant GBW thickening. The final diagnoses were 48 gallbladder carcinomas and 111 benign gallbladder diseases. Maximal thicknesses of the GBW in malignant and benign GBW thickening were 17.3 ± 5.2 (6-30) mm and 8.6 ± 5.1 (4-26) mm respectively (p < 0.001). CEUS revealed significant differences in intra-lesional vessels, enhancement homogeneity, time to hypo-enhancement, inner layer discontinuity, outer layer discontinuity and adjacent liver involvement (all p-values < 0.05) between malignant and benign GBW thickening. Patient age > 46.5 y, focal GBW thickening, inner layer discontinuity and outer layer discontinuity were found to be associated with malignancy by multiple logistic regression analysis (all p-values < 0.05). Receiver operating characteristic curve analysis revealed Az values for patient age, focal GBW thickening, inner wall discontinuity and outer wall discontinuity of 0.709 (95% confidence interval [CI]: 0.627-0.790), 0.714 (95% CI: 0.630-0.798), 0.860 (95% CI: 0.791-0.928) and 0.858 (95% CI: 0.783-0.933), respectively. CEUS is useful in the differential diagnosis between malignant and benign GBW thickening. Focal GBW thickening, inner wall discontinuity and outer wall discontinuity observed on CEUS are diagnostic clues for malignant GBW thickening.