| Objective: To determine the optimal delay times for multiphase contrast-enhanced MDCT of pancreas, and to evaluate the display rate of peripancreatic vessels using this scanning technique.Materials and methods: (1). 20 patients with normal pancreas were selected randomly, and all of them underwent single-level contrast-enhanced MDCT examinations of pancreas. The contrast media was injected with a dosage of 100 ml and at a rate of 4 ml/s. The peak value (HU) and the time to peak value of ROI (including peripancreatic aorta, portal vein, pancreatic and hepatic parenchyma) were obtained. (2). 40 patients with normal pancreas were selected at random for 3-phasic contrast-enhanced MDCT of pancreas, and the display rates of peripancreatic vessels were analyzed.Results: (1). The average time to peak value of the peripancreatic aorta, portal vein, pancreatic and hepatic parenchyma were about 30s, 45s, 40s, and 55s, respectively. The average CT value of peripancreatic aorta was 316HU at 20s, the platform stage for hepatic parenchyma ranged from 55 to 75s. (2). The display rate of main peripanceatic arteries was 100%, the display rate of the other peripancreatic arteries except AIPDA was 75-100%. The display rate of main peripanceatic veins was 100%, the display rate of the other peripancreatic veins except AIPDV was also 75-100%.Conclusion: With the contrast dosage of 100ml and the injection rate of 4ml/s, the optimal delay times for 3-phasic contrast-enhanced MDCT of pancreas were suggested as follows: 20s for arterial phase, 45s for pancreatic parenchyma phase, and 70s for hepatic phase. Objective: To evaluate the effects of MDCT scans with different contrast-enhanced phases in preoperative surgical resectability assessment of pancreatic carcinoma.Materials and Methods: (1). 257 patients suspected of having pancreatic cancer were divided into 3 groups, and MDCT scans were obtained with different scanning techniques for these groups: group 1, with arterial phase and portal venous phase; group 2, with pancreatic parenchyma phase and portal venous phase; group 3, with arterial phase, pancreatic parenchyma phase and portal venous phase. (2). For patients with pancreatic carcinomas, their locations and sizes, peripancreatic organic involvement, peripancreatic vascular invasions, and metastases to liver or to peritoneum pancreatic, if there was any, were included in the imaging analyses. The tumor resectability was also evaluated and eventually correlated with surgical and histopathologic results. (3). The positive predictive value, negative predictive value, sensitivity, specificity and accuracy were calculated in the end.Results: (1). The positive predictive value, negative predictive value, sensitivity, specificity and accuracy of these three groups were as follows respectively: 93.5%, 66.7%, 87.9%, 80.0%, 86.0% for group 1; 100%, 80.0%, 93.8%, 100%, 95.0% for group 2; and 100%, 87.5%, 97.1%, 100%, 97.6% for group 3. (2). The accuracy in evaluation of peripancreatic organic involvement in 3 groups were 96.1%, 98.1%, and 98.5%, respectively. (3). The accuracy in prediction of peripancreatic vascular invasion in 3 groups were 96.8%, 97.8%, and 98.2%, respectively.Conclusion: (1). For patients suspected of having pancreatic cancer, the pancreatic parenchymal phase and the portal venous phase should be obtained as the basic MDCT scan phases. The arterial phase could be added, in order to evaluate the peripancreatic vasculature and blood supply to the tumor. (2). The original axial MDCT scans, together with the advanced postprocessing techniques such as MPR, MIP, VR and CPR, are of great help in preoperative tumor resectability assessment of pancreatic cancer.
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