RESUMO
AIM: 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. MATERIALS AND METHODS: All patients presenting with suspicious gallbladder lesions between January 2011 and December 2016 who underwent DWI and histopathological diagnoses of the lesions were assessed. RESULTS: 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. CONCLUSION: The b800/b0 ratio can help differentiate benign and malignant gallbladder lesions and may be more reliable than ADC values in quantitative DWI assessments.