Contrast-enhanced CT with saline flush technique using two automated injectors: How much contrast medium does it save?

Purpose: The purpose of this work was to investigate the volume of contrast medium saved by the saline flush technique. Method: Thoracic helical CT was performed by injecting 75 ml of contrast material (loversol 320) only (n = 25; Group A) or 75 ml of contrast medium pushed with 6 ml (n = 25; Group B), 12 ml (n = 25 Group C), 25 ml (n = 25, Group D), or 50 ml (n = 25; Group E) of saline at a rate of 2 ml/s. The aortic CT numbers were measured from 30 to 55 s after the beginning of injection. We compared the time to peak aortic enhancement (TPAE) among Groups A-E. Results: The TPAEs of the Groups A-E were 42.6, 45.2, 48.6, 48,4, and 48.3 s. respectively, and there was a statistically significant difference among them (p < 0.0001, analysis of variance). Post hoc test revealed statistically significant differences in TPAE between Groups A and B, C, D, and E and between Groups B and C, D, and E but no differences among Groups C, D, and E. Conclusion: The saline flush technique prolongs TPAE by 6 s and saves 12 ml of contrast medium.