Differentiation of pancreas carcinoma from healthy pancreas using diffusion-weighted MR imaging: comparison of apparent diffusion coefficient and intravoxel incoherent motion-derived parameters

Objective: To evaluate the diagnostic performance of multi-b value DWI to differentiate pancreatic adenocarcinoma from healthy pancreas using the apparent diffusion coefficient (ADC) and parameters derived from the intravoxel incoherent motion (IVIM) theory. Methods: Forty-eight patients with histopathologically proven pancreatic adenocarcinoma and fifty patients with healthy pancreas were examined at 3.0 Tesla using a single-shot echo-planar imaging DWI pulse sequence. Eight b-values ranging from 0 to 1000 s/mm² were used. ADC, diffusion coefficient (D), perfusion-related diffusion (D) and perfusion fraction (f) were compared between pancreatic adenocarcinoma and healthy pancreas, t test or Mann-Whitney U test was used to compare the MRI parameters, ROC was used to evaluate the diagnostic efficiency. Results: In comparison to healthy pancreatic tissue, a significant reduction of the ADC, D^* and f was found in pancreatic adenocarcinoma [healthy pancreatic tissue:(1.68 ± 0.31) × 10^-3 mm²/s, 27.10 × 10^-3 mm²/s, (36.92 ± 12.47)%; pancreatic adenocarcinoma: (1.51 ± 0.37) × 10^-3 mm²/s, 13.90 × 10^-3 mm²/s, (30.06 ± 19.84)%] (P < 0.05). No significant difference in the diffusion coefficient D was observed between the two groups (1.06 × 10^-3 and 1.26 × 10^-3 mm²/s; P > 0.05). In the ROC-analyses, the area under curve for D^* was the largest (0.727), followed by f and ADC in order (0.680 and 0.669). Conclusion: Using the IVIM DWI approach, the D^*, f and ADC value are useful for differentiating pancreatic adenocarcinoma from healthy pancreatic tissue. (authors)