Diagnostic nomogram for gallbladder wall thickening mimicking malignancy: using contrast-enhanced ultrasonography or multi-detector computed tomography?

OBJECTIVES: To establish a diagnostic nomogram using contrast-enhanced ultrasonography (CEUS) in gallbladder wall thickening mimicking malignancy and compare with multi-detector computed tomography (MDCT).

METHODS: Seventy-two patients with gallbladder wall thickening on B-mode ultrasonography (BUS) were examined by CEUS to develop independent predictors for diagnosing gallbladder carcinoma. Among the 72 cases, 48 patients underwent both CEUS and MDCT. The diagnostic performances of different sets of CEUS criteria and MDCT were compared. A prediction model of malignancy using CEUS was developed. The performance of the nomogram was assessed with respect to its calibration, discrimination, and clinical usefulness.

RESULTS: Multivariate logistic regression indicated that inhomogeneous enhancement in the arterial phase was the strongest independent predictor of malignancy (odds ratio, OR 51.162), followed by interrupted inner layer (OR 19.788), washout time ≤40 s (OR 16.686), and wall thickness >1.6 cm (OR 3.019), which were all selected into the nomogram. Combined with the above significant features, the diagnostic performance of CEUS (AUC = 0.917) was higher than that of MDCT (AUC = 0.788, P = 0.070). The predictive model using CEUS showed good discrimination, with a concordance index of 0.974 (0.950 through internal validation), and good calibration. Decision curve analysis demonstrated that the nomogram was clinically useful.

CONCLUSIONS: CEUS could accurately differentiate between malignant and benign gallbladder wall thickening with equivalent efficacy compared to MDCT. The proposed nomogram could be conveniently used to facilitate the preoperative individualized prediction of malignancy in patients with gallbladder wall thickening.