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 ϭ 71; pancreatic cancer [n ϭ 47], mass-forming pancreatitis [n ϭ 13], solid pseudopapillary neoplasm [n ϭ 6], and neuroendocrine tumor [n ϭ 5]) and a normal control group (n ϭ 11) by applying three b-factors of 0, 500, and 1000 sec/mm 2 . ADC 500 , ADC 1000 , D (ADC using b ϭ 500 and 1000 sec/mm 2 ), and perfusion fraction (f, 1-exp [-500 sec/mm 2 ϫ (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 Ͻ 0.001, Ͻ 0.001, and 0.004, respectively) or mass-forming pancreatitis (P Ͻ 0.001, Ͻ 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 ϭ 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.
