Impact of CT injector technology and contrast media viscosity on vascular enhancement: Evaluation in a circulation phantom.

Objective: To assess the impact of piston-based vs peristaltic injection system technology and contrast media viscosity on achievable iodine delivery rates (IDRs) and vascular enhancement in a pre-clinical study. Methods: Four injectors were tested: MEDRAD (R) Centargo, MEDRAD (R) Stellant, CT Expres (R), and CT motionT using five contrast media [iopromide (300 and 370 mgI ml(-1)), iodixanol 320 mgI ml(-1), iohexol 350 mgI ml(-1), iomeprol 400mgI ml(-1)]. Three experiments were performed evaluating achievable IDR and corresponding enhancement in a circulation phantom. Results: Experiment I: Centargo provided the highest achievable IDRs with all tested contrast media (p < 0.05). Iopromide 370 yielded the highest IDR with an 18G catheter (3.15 gI/s); iopromide 300 yielded the highest IDR with 20G (2.70 gI/s) and 22G (1.65 gI/s) catheters (p < 0.05). Experiment II: with higher achievable IDRs, piston-based injectors provided significantly higher peak vascular enhancement (up to 48% increase) than the peristaltic injectors with programmed IDRs from 1.8 to 2.4 gI/s (p < 0.05). Experiment III: with programmed IDRs (e.g. 1.5 gI/s) achievable by all injection systems, Centargo, with sharper measured bolus shape, provided significant increases in enhancement of 34-73 HU in the pulmonary artery with iopromide 370 (p < 0.05). Conclusion: The tested piston-based injection systems combined with low viscosity contrast media provide higher achievable IDRs and higher peak vascular enhancement than the tested peristaltic-based injectors. With equivalent IDRs, Centargo provides higher peak vascular enhancement due to improved bolus shape. Advances in knowledge: This paper introduces a new parameter to compare expected performance among contrast media: the concentration/viscosity ratio. Additionally, it demonstrates previously unexplored impacts of bolus shape on vascular enhancement.