64-section multidetector CT of the upper abdomen: optimization of a saline chaser injection protocol for improved vascular and parenchymal contrast enhancement
Objectives To prospectively investigate the effect of varying the injection flow rates of a saline chaser on vascular and parenchymal
contrast enhancement during abdominal MDCT.
Methods 100 consecutive patients were randomly assigned to four injection protocols. A fixed dose of contrast medium was administered
followed by no saline (Protocol A) or 50 mL of saline at 2, 4, or 8 mL/s (Protocols B, C, and D). Peak, time-to-peak, and
duration of 90% peak enhancement were determined for aorta, pancreas, and liver.
Results Aortic peak enhancement was significantly higher for Protocol D (369.5 HU) compared with Protocols A and B (332.9 HU and 326.0 HU,
respectively; P < 0.05). Pancreatic peak enhancement was significantly higher for Protocols C and D (110.6 HU and 110.9 HU, respectively)
compared to Protocol A (92.5 HU; P < 0.05). Aortic and pancreatic time-to-peak enhancement occurred significantly later for Protocol D compared with Protocol
A (42.8 s vs. 36.1 s [P P = 0.003]).
Conclusions Injecting a saline chaser at high flow rates yields significantly higher peak aortic and pancreatic enhancement, with a slight
longer time-to-peak enhancement.