Quantitative analysis of diffusion‐weighted magnetic resonance imaging of the pancreas: Usefulness in characterizing solid pancreatic masses

Purpose To evaluate whether measurement of apparent diffusion coefficient (ADC) and pure diffusion coefficient ( D ) can help to characterize solid pancreatic masses. Materials and Methods Diffusion‐weighted MR imaging was performed in both a patient group ( n = 71; pancreatic cancer [ n = 47], mass‐forming pancreatitis [ n = 13], solid pseudopapillary neoplasm [ n = 6], and neuroendocrine tumor [ n = 5]) and a normal control group ( n = 11) by applying three b‐factors of 0, 500, and 1000 sec/mm 2 . ADC 500 , ADC 1000 , D (ADC using b = 500 and 1000 sec/mm 2 ), and perfusion fraction ( f , 1‐ exp [‐500 sec/mm 2 × (ADC 500 – D )]) of normal pancreas, pancreatic cancer, and mass‐forming pancreatitis were compared using the Kruskal–Wallis test. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance and optimal cutoff value of these parameters in differentiating pancreatic cancer from mass‐forming pancreatitis. Results Normal pancreas had significantly higher mean ADC 500 , ADC 1000 , and f than either pancreatic cancer ( P < 0.001, < 0.001, and 0.004, respectively) or mass‐forming pancreatitis ( P < 0.001, < 0.001, and 0.002, respectively). ADC 500 , ADC 1000 , and D of mass‐forming pancreatitis were significantly lower than those of pancreatic cancer ( P = 0.002, 0.004, and 0.014, respectively). Sensitivities and specificities in the diagnosis of pancreatic cancer were 72.3% and 76.9% for ADC 500 , 87.2% and 69.2% for ADC 1000 , 87.2% and 61.5% for D , and 42.6% and 92.3% for f , respectively. Conclusion Measurement of ADC and D may be helpful in differentiating pancreatic cancers from mass‐forming pancreatitis. J. Magn. Reson. Imaging 2008;28:928–936. © 2008 Wiley‐Liss, Inc.