Comparison between one-route and two-route injection for liver and aortic enhancement using MDCT

The purpose of our study was to evaluate whether simultaneous injection into cubital veins bilaterally at one half of the standard injection rate achieves similar hepatic and aortic enhancement on MDCT as the conventional injection rate into a single cubital vein.

Thirty-two patients underwent multiphase MDCT because they were suspected of having a hepatic tumor. Patients were assigned to one of the following two groups: group A, 100 mL of 370 mg I/mL of contrast medium injected into a unilateral cubital vein (one-route) via a 20-gauge cannula at a rate of 4 mL/s; or group B, 50 mL of contrast medium injected into the cubital veins bilaterally (two-route) via 24-gauge cannulas at 2 mL/s. Peak contrast enhancement of the liver and abdominal aorta for groups A and B was measured using regions of interest and compared; arrival time of the contrast media was also compared using a bolus-tracking system. Analysis was performed using Wilcoxon's signed rank test.

Peak aortic enhancement of groups A and B was 367 +/- 67 H and 361 +/- 113 H (p = 0.61, not significant), respectively, and peak hepatic enhancement of groups A and B was 56 +/- 11 H and 56 +/- 16 H (p = 0.88, not significant), respectively. Mean arrival time to the aorta of group B (19.4 +/- 3.4 seconds) was significantly later compared with that of group A (15.5 +/- 3.5 seconds) (p = 0.005).

The slower two-route injection produced the same aortic and hepatic enhancement as the faster one-route method with faster injection, but the arrival time of the contrast medium was later using the two-route method.