Evaluation of two injection protocols by time-density curves for possible application to hepatic dynamic and upper abdominal CT angiography in MDCT: high concentration (350 mgI/ml) with conventional volume (100 ml) vs. conventional concentration (300 mgI/ml) with larger volume (150 ml) and higher injection rate]

The purpose of this study was to compare two different injection protocols for possible application to hepatic dynamic CT and CT angiography of the upper abdomen. Single-level dynamic CT scans through the level of the porta heapatis were performed with an MDCT unit every 3 sec in 32 patients using protocol A (350 mgI/ml iodine contrast medium, total volume 100 ml, injection rate 3.0 ml/sec), and in 39 patients using protocol B (300 mgI/ml, 150 ml, 4.5 ml/sec). Injection duration was kept the same in the two protocols. Time-density curves of the abdominal aorta (Ao), liver (L), and portal vein (PV) were created and compared. Peak enhancements were significantly higher in protocol B than in protocol A, in all of Ao, L, and PV. Time to peak enhancement was shorter in protocol B than in protocol A, reaching statistical significance in Ao and PV, but not in L. The duration of the arterial phase was shorter in protocol B than in protocol A, but the difference was not statistically significant. Our data suggest the superiority of protocol B over protocol A, for possible application to hepatic dynamic CT and CT angiography of the upper abdomen in MDCT.