Determination of the least amount of iodine load required for the detection of pancreatic adenocarcinoma at 80-kVp CT

Abstract

Purpose To determine the iodine load per body weight (ILPBW) that is minimally required for the detection of pancreatic adenocarcinoma for 80 kVp CT imaging. Material and methods Institutional review board approval and written informed consent were obtained. Fifty-seven consecutive patients with histopathologically-proven pancreatic adenocarcinoma were assigned to three groups at random according to iodine load (0.5, 0.4, and 0.3 gI/kg) and underwent CT at 80 kVp. Enhancement of the pancreas and visualization of the tumor were assessed during the pancreatic parenchymal-phase and compared among the three groups. The relationship between the iodine load and tumor conspicuity was also analyzed. Results The mean CT number of the pancreas (HUpancreas) was higher in the 0.5 gI/kg group (158.8HU) than in the 0.4 (121.7HU) and 0.3 (106.6HU) gI/kg groups (P < 0.05). Tumor-to-pancreas contrast (HUtumor-to-pancreas) was also higher in 0.5 gI/kg group (88.9HU) than in 0.4 (62.2HU) and 0.3 (54.5HU) gI/kg groups (P < 0.05). Linear regression between HUpancreas or HUtumor-to-pancreas and ILPBW were expressed as HUpancreas = 23.3 + 263.9 × ILPBW (r = 0.74, P < 0.0001) and HUtumor-to-pancreas = -1.24 + 174.3 × ILPBW (r = 0.56, P < 0.0001), respectively. The iodine load estimated to achieve an acceptable HUpancreas (>100HU) and HUtumor-to-pancreas (>50HU) were 0.29 and 0.30 gI/kg, respectively. Conclusion An iodine load of 0.3 gI/kg was the least amount required for the detection of pancreatic adenocarcinoma at 80 kVp CT.