HELICAL CT OF THE LIVER - EVALUATION OF INJECTION FLOW-RATE, MODE, AND SCAN DELAY WITH A REDUCED-VOLUME CONTRAST-MEDIUM BOLUS

Objective: The impact of injection flow rates, mono- or biphasic injection mode, and scan delay on liver and portal vein enhancement with helical CT was evaluated. Materials and Methods: The liver of 75 consecutive patients was examined with helical CT before and after injection of 100 ml iopromide (30 g of iodine). Patients were randomly assigned to three protocols: (1) injection flow: 2 ml/s; (2) injection flow: 4 ml/s (60 ml) + 2 ml/s (40 ml); and (3) injection flow: 4 ml/s. Scanning started 40 s after the beginning of contrast material injection. A second scan was performed 70 s after contrast agent injection in Protocol 1. Results: Mean parenchymal contrast enhancement was highest with Protocol 3 (48.5 HU) followed by Protocols 2 (38.9 HU) and 1 (early: 21 HU; late: 30.7 HU), with all differences being significant (p < 0.01). Enhancement of the portal vein was significantly higher with Protocols 3 and 2 (121 and 118 HU) than with Protocol 1 (early: 64 HU; late: 75 HU). Conclusion: Good enhancement of the liver parenchyma and the portal vessels can be obtained with 30 g of iodine if a monophasic injection with a flow rate of 4 ml/s is used.