The value of diffusion-weighted imaging in diagnosing gallbladder malignancy: performance of a new parameter

Abstract

To assess the value of the ratio of signal intensities at high and low b-values (b800/b0 ratio) during diffusion-weighted imaging (DWI) for gallbladder cancer diagnosis. All patients presenting with suspicious gallbladder lesions between January 2011 and December 2016 who underwent DWI and histopathological diagnoses of the lesions were assessed. Thirty-two patients (24 men, eight women) were identified. Eighteen patients had benign gallbladder lesions while 14 had malignant lesions. The mean apparent diffusion coefficient (ADC) value was 1.62 (±0.57)×10-3 mm2/s for benign cases and 1.27 (±0.39)×10-3 mm2/s for malignant cases; this difference was not significant (p=0.0773). The mean b800/b0 ratio was 0.31 (±0.19) for benign cases and 0.48 (±0.13) for malignant cases; this difference was significant (p=0.007). The ROC curve for b800/b0 had an AUC of 0.782 (95% confidence interval [CI]: 0.616-0.947) with a sensitivity and specificity of 85.7% and 72.2%, respectively, at a cut-off point of 0.33. The b800/b0 ratio can help differentiate benign and malignant gallbladder lesions and may be more reliable than ADC values in quantitative DWI assessments.