Pancreatic ductal adenocarcinoma and chronic mass-forming pancreatitis: Differentiation with dual-energy MDCT in spectral imaging mode

Abstract Objective To investigate the value of dual-energy MDCT in spectral imaging in the differential diagnosis of chronic mass-forming chronic pancreatitis (CMFP) and pancreatic ductal adenocarcinoma (PDAC) during the arterial phase (AP) and the pancreatic parenchymal phase (PP). Materials and methods Thirty five consecutive patients with CMFP ( n  = 15) or PDAC ( n  = 20) underwent dual-energy MDCT in spectral imaging during AP and PP. Iodine concentrations were derived from iodine-based material-decomposition CT images and normalized to the iodine concentration in the aorta. The difference in iodine concentration between the AP and PP, contrast-to-noise ratio (CNR) and the slope K of the spectrum curve were calculated. Results Normalized iodine concentrations (NICs) in patients with CMFP differed significantly from those in patients with PDAC during two double phases (mean NIC, 0.26 ± 0.04 mg/mL vs. 0.53 ± 0.02 mg/mL, p  = 0.0001; 0.07 ± 0.02 mg/mL vs. 0.28 ± 0.04 mg/mL, p  = 0.0002, respectively). There were significant differences in the value of the slope K of the spectrum curve in two groups during AP and PP ( K CMFP  = 3.27 ± 0.70 vs. K PDAC  = 1.35 ± 0.41, P  = 0.001, and K CMFP  = 3.70 ± 0.17 vs. K PDAC  = 2.16 ± 0.70, p  = 0.003, respectively). CNRs at low energy levels (40–70 keV) were higher than those at high energy levels (80–40 keV). Conclusion Individual patient CNR-optimized energy level images and the NIC can be used to improve the sensitivity and the specificity for differentiating CMFP from PDAC by use of dual-energy MDCT in spectral imaging with fast tube voltage switching.