Enhancement parameters of contrast-enhanced computed tomography for pancreatic ductal adenocarcinoma: Correlation with pathologic grading

BACKGROUND: Pancreatic ductal adenocarcinoma (PDA) is a malignancy with a high mortality rate and short survival time. The conventional computed tomography (CT) has been worldwide used as a modality for diagnosis of PDA, as CT enhancement pattern has been thought to be related to tumor angiogenesis and pathologic grade of PDA. AIM: To evaluate the relationship between the pathologic grade of pancreatic ductal adenocarcinoma and the enhancement parameters of contrast-enhanced CT. METHODS: In this retrospective study, 42 patients (Age, mean ± SD: 62.43 ± 11.42 years) with PDA who underwent surgery after preoperative CT were selected. Two radiologists evaluated the CT images and calculated the value of attenuation at the aorta in the arterial phase and the pancreatic phase (VA(arterial) and VA(pancreatic)) and of the tumor (VT(arterial) and VT(pancreatic)) by finding out four regions of interest. Ratio between the tumor and the aorta enhancement on the arterial phase and the pancreatic phase (TAR(arterial) and TAR(pancreatic)) was figured out through dividing VT(arterial) by VA(arterial) and VT(pancreatic) by VA(pancreatic). Tumor-to-aortic enhancement fraction (TAF) was expressed as the ratio of the difference between attenuation of the tumor on arterial and parenchymal images to that between attenuation of the aorta on arterial and pancreatic images. The Kruskal-Wallis analysis of variance and Mann-Whitney U test for statistical analysis were used. RESULTS: Forty-two PDAs (23 men and 19 women) were divided into three groups: Well-differentiated (n = 13), moderately differentiated (n = 21), and poorly differentiated (n = 8). TAF differed significantly between the three groups (P = 0.034) but TAR(arterial) (P = 0.164) and TAR(pancreatic) (P = 0.339) did not. The median value of TAF for poorly differentiated PDAs (0.1011; 95%CI: 0.01100-0.1796) was significantly higher than that for well-differentiated PDAs (0.1941; 95%CI: 0.1463-0.3194). CONCLUSION: Calculation of TAF might be useful in predicting the pathologic grade of PDA.