The characteristics of pancreatic ductal adenocarcinoma with single-source dual energy spectral CT imaging

Abstract

Objective To explore the quantitative characteristics of pancreatic ductal adenocarcinoma (PDAC) in single-source dual energy spectral CT imaging. Methods From January 2013 to December 2014, 113 patients underwent dual phase contrast-enhanced gemstone spectral imaging (GSI) on Discovery CT 750 HD. All diagnoses were pathologically confirmed by surgery or biopsy. The spectral HU curves of PDAC were observed, the monochromatic CT values, the effective atomic number (Zeff), the iodine concentration (IC), water concentration (WC), and the corresponding normalized values (normalized monochromatic CT values, normalized Zeff, normalized IC, normalized WC) of the lesion and the pancreatic parenchyma in late arterial phase (AP) and portal venous phase (PP) were recorded. The measurements were performed three times repeatedly. Paired t test (normal distribution) or Wilcoxon test (non-normal distribution) were used for analyzing the differences between the two phases and between PDAC and pancreatic parenchyma. Results The monochromatic CT values of PDAC in AP were lower than in PP at each energy level and the difference was more marked at lower energy. The normalized monochromatic CT values increased with the increase of energy level in both AP and PP and the difference was more distinct at lower energy. The Zeff, IC and normalized IC of PDAC all had significant differences (P<0.05), while the WC, normalized Zeff, and normalized WC had no difference between AP and PP. The Zeff and IC of pancreatic parenchyma had significant differences (P<0.05), while the WC had no difference between AP and PP. The differences of Zeff, IC, and WC between PDAC and pancreatic parenchyma were significant in both two phases (P<0.05). Conclusions Dual phase CT spectral imaging showed characteristic quantitative parameters of pancreatic ductal adenocarcinoma. The monochromatic CT values, Zeff, and iodine concentration of PDAC were lower than those of pancreatic parenchyma in both AP and PP. The monochromatic CT values, Zeff, and iodine concentration of PDAC in late arterial phase were lower than those in portal venous phase. The differences were all more distinct at lower energy. Key words: Pancreatic neoplasms; Tomography, X-ray computed; Comparative study