Pancreas: Patient Body Weight–tailored Contrast Material Injection Protocol versus Fixed Dose Protocol at Dynamic CT

Abstract

To prospectively compare the effect of a protocol with a fixed contrast material injection dose and one with a dose tailored to patient body weight on pancreatic enhancement at dynamic computed tomography (CT) of the pancreas. This study was approved by the institutional review board, and patients gave informed consent. Seventy-eight patients suspected of having pancreatic tumor were randomly assigned to one of two protocols (39 patients in each protocol). In protocol 1, a fixed contrast material dose (120 mL of iohexol 300) was delivered at an injection rate of 4.0 mL/sec; in protocol 2, a dose tailored to the patient's body weight (2.0 mL/kg) was injected over the course of 30 seconds. Scans were started 25, 45 (pancreatic parenchymal phase [PPP]), and 70 (portal venous phase [PVP]) seconds after the initiation of contrast material injection. Pancreatic enhancement during the PPP and hepatic enhancement during the PVP were compared by using the Student t test in patients whose body weight was less than 60 kg (group A) or 60 kg or greater (group B). A radiologist who was blinded to the injection protocol used measured the CT number of each organ. With protocol 1, mean pancreatic enhancement during the PPP was 94.1 HU in group A and 76.1 HU in group B; the difference was statistically significant (P = .02). With protocol 2, mean pancreatic enhancement was 89.5 HU in group A and 84.7 HU in group B; there was no significant difference (P = .45). Mean hepatic enhancement with protocol 1 during the PVP was 59.6 HU in group A and 48.5 HU in group B (P < .01); with protocol 2, it was 55.4 HU in group A and 58.3 HU in group B. The difference was not statistically significant (P = .34). The dose protocol tailored to the patient's body weight yielded satisfactory pancreatic and hepatic enhancement irrespective of patient weight.