64-section multidetector CT of the upper abdomen: optimization of a saline chaser injection protocol for improved vascular and parenchymal contrast enhancement
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 (Ioversol 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.