High b-value diffusion-weighted magnetic resonance imaging for gallbladder lesions: differentiation between benignity and malignancy.

BACKGROUND: Recently, the clinical application of diffusion-weighted magnetic resonance imaging (DWI) has been expanding to abdominal organs. However, only a few studies on gallbladder diseases have been published. The aim of this study was to evaluate the usefulness and limitations of high b-value DWI for gallbladder diseases.

METHODS: A total of 153 patients (mean age 60 ± 15 years, 78 males) who had undergone DWI for evaluating gallbladder wall thickening or polypoid lesions were included in this study. Of these 153 patients, 36 had gallbladder cancer and 117 had benign gallbladder diseases (67 chronic cholecystitis, 44 adenomyomatosis, four cholesterol polyp, one gallbladder adenoma, and one xanthogranulomatous cholecystitis). We evaluated the positive signal rate with DWI and the apparent diffusion coefficient (ADC) value of each disease.

RESULTS: The positive signal rate with DWI was significantly higher in gallbladder cancer (78 %) than in benign gallbladder diseases (22 %) (p < 0.001). The mean ADC value of gallbladder cancer was (1.83 ± 0.69) × 10(-3) mm(2)/s and that of benign gallbladder diseases was (2.60 ± 0.54) × 10(-3) mm(2)/s (p < 0.001). Benign gallbladder diseases with acute cholecystitis or a history of that had a higher positive signal rate with DWI (p < 0.001) and a lower ADC value (p = 0.018) than those without such conditions.

CONCLUSION: DWI can contribute to the improvement of the diagnostic capability for gallbladder wall thickening or polypoid lesions by compensating for weaknesses of other modalities by its many advantages, although cases with acute cholecystitis or such history sometimes show false-positive on DWI.