Injection pressure in contrast-enhanced computed tomography is influenced by catheter size, contrast medium type, and injection rate.

Maintaining stable injection pressure is essential for safe and effective contrast-enhanced computed tomography (CE-CT), but the combined effects of procedural factors on maximum injection pressure remain unclear. This retrospective study analyzed 4223 CE-CT examinations performed between April 2022 and March 2025 using data automatically recorded by an integrated CE-evidence system. A general linear model was used to evaluate the effects of IV catheter size (20G or 22G), injection rate (2.5, 3.0, or 3.5 mL/s), and contrast medium (CM) type on maximum injection pressure after adjustment for age, sex, and body mass index. IV catheter size had the greatest effect on maximum injection pressure (partial η² = 0.247, p < 0.001), with significantly higher pressures for 22G than for 20G catheters. CM type (partial η² = 0.159, p < 0.001) and injection rate (partial η² = 0.075, p < 0.001) were also significant independent factors. Significant two-way interactions were observed between IV catheter size and injection rate, IV catheter size and CM type, and injection rate and CM type (all p < 0.001), whereas the three-way interaction was not significant (p = 0.129). Adjusted estimated marginal means showed that the increase in maximum injection pressure with higher injection rates was greater for 22G than for 20G catheters. These findings indicate that maximum injection pressure is determined by both individual procedural factors and their interactions, and that optimizing combinations of IV catheter size, CM type, and injection rate may help reduce excessive injection pressure in clinical practice.