Value of diffusion-weighted MRI in differentiation between benign and malignant polypoid gallbladder lesions

Objective: To evaluate the efficiency of diffusion-weighted MRI in differentiating between benign and malignant polypoid gallbladder lesions.

Methods: The study population consisted of 10 benign (5 polyps, 3 adenomyomatosis and 2 adenomas) and 13 malignant (all adenocarcinomas) polypoid gallbladder lesions treated in hospital from November 2007 to May 2014. DWI was evaluated by two observers. Qualitatively, the signal intensity of the lesions on DWI was visually evaluated and categorized as iso, high, or very high signal.Quantitatively, the ADC values of the lesions were measured from ADC maps. Statistical analysis was performed using a two-tailed Fisher's exact test and the Mann-Whitney test, respectively. The cut-off values were determined by receiver operating characteristic analysis.

Results: Qualitative analysis revealed a statistical difference (P=0.036). In the 10 benign lesions, three were categorized as iso, 5 as high, and 2 as very high signal.Four of the 13 malignant lesions were categorized as high, and the remaining 9 were categorized as very high signal. The mean ADC value of the malignant lesions [(1.13±0.28)×10(-3) mm2/s] was significantly lower than that of benign lesions [(2.22±0.42)×10(-3) mm2/s, P<0.01]. The cut-off value between cancer and the benign lesions was 1.5×10(-3) mm2/s, the sensitivity, specificity, and accuracy were 92%, 100% and 96%, respectively.

Conclusions: Diffusion-weighted MRI may be useful in differentiating between benign and malignant polypoid gallbladder lesions.