Optimization of Scan Delay in Contrast Enhanced Computed Tomography of Pancreas Using Bolus Tracking Category

Abstract

Introduction: Pancreatic pathologies present a challenge for the medical imaging professionals for detection, classification and staging. Multiphasic multidetector computed tomography provides detailed visualization and definition of deeper and smaller structures and enhancement pattern of tumors during different phases. The objective of this study was to optimize the scan delay time for contrast enhanced computed tomography of pancreas after the use of bolus tracking technique. Materials and methods: Triphasic MDCT of the pancreas was performed on 109 patients after administration of 300-350 mgI/mL contrast medium injected at 3.5 mL/s. Patients were prospectively randomized into three groups with different scanning delays for the three phases (arterial, pancreatic, and venous) after bolus tracking was triggered at 100 HU of aortic contrast enhancement. Mean attenuation values of the abdominal aorta, superior mesenteric artery, pancreatic parenchyma, splenic vein, portal vein, and hepatic parenchyma were measured. Increases in attenuation values after contrast administration were assessed. Results: Mean contrast enhancement in the aorta (change in attenuation, 313–320 HU) and the superior mesenteric artery (change in attenuation, 291–302 HU) approached peak enhancement 4-7 seconds after bolus tracking was triggered. Pancreatic parenchyma became most intensely enhanced (change in attenuation, 107–110 HU) 20-25 seconds after triggering, and then the enhancement gradually decreased. Enhancement of the splenic vein and portal vein peaked at 22 seconds. Liver parenchyma reached 71 HU, 25 seconds after triggering and reached a plateau (change in attenuation, 81-76 HU) at a further scanning delay of 45–50 seconds. Conclusion: Based on the protocol used in this study, the optimum scan delay were 4-7 seconds for arterial phase, 10-22 seconds for pancreatic parenchymal phase and 40-50 seconds for the hepatic parenchymal phase; after bolus tracking triggered at 100 HU in the abdominal aorta.