Apparent diffusion coefficient in pancreatic cancer: characterization and histopathological correlations

PURPOSE: To clarify the components primarily responsible for diffusion abnormalities in pancreatic cancerous tissue. MATERIALS AND METHODS: Subjects comprised 10 patients with surgically confirmed pancreatic cancer. Diffusion-weighted (DW) echo-planar imaging (b value = 0, 500 s/mm(2)) was employed to calculate the apparent diffusion coefficient (ADC). ADC values of cancer and noncancerous tissue were calculated. Furthermore, ADC values of the cancer were compared with histopathological results. RESULTS: The mean (+/-standard deviation) ADC value was significantly lower for tumor (1.27 +/- 0.52 x 10(-3) mm(2)/s) than for noncancerous tissue (1.90 +/- 0.41 x 10(-3) mm(2)/s, P < 0.05). Histopathological examination showed similar proportions of fibrotic area, cellular component, necrosis, and mucin in each case. Regarding the density of fibrosis in cancer, three cases were classified in the loose fibrosis group and the remaining seven cases were classified in the dense fibrosis group. The mean ADC value was significantly higher in the loose fibrosis group (1.88 +/- 0.39 x 10(-3) mm(2)/s) than in the dense fibrosis group (1.01 +/- 0.29 x 10(-3) mm(2)/s, P < 0.05). In quantitative analysis, ADC correlated well with the proportion of collagenous fibers (r = -0.87, P < 0.05). CONCLUSION: Collagenous fibers may be responsible for diffusion abnormalities in pancreatic cancer.