Piston-Based vs Peristaltic Pump-Based CT Injector Systems

Purpose To compare the fluid delivery performance of 2 different technologies for administration of iodinated contrast media in computed tomography (CT). Methods The maximum achievable flow rate and the steady-state flow rate variance of a piston-based contrast media injector system (Stellant MP, MEDRAD) was compared with peristaltic pump-based injector systems (CT motion, Ulrich Medical; CT Expres, Bracco). The contrast media iopromide (Ultravist) and iopamidol (Isovue) were used at 2 concentrations each (300 and 370 mg I/mL) and 3 catheter sizes (18, 20, and 22 G) to test the injector performance. Results Average maximum achievable flow rates for room temperature iopromide (370 mg I/mL) using a 20 G catheter were 7.6, 7.1, and 4.8 mL per second for the Stellant MP injector, CT motion injector, and CT Expres injector, respectively. The Stellant MP injector achieved significantly higher flow rates compared to the CT Expres injector for all catheter sizes tested (P < .001). Higher flow rates also were observed for the Stellant MP injector compared to the CT motion injector, with 20 G and 22 G catheters (P < .001). The Stellant MP injector featured a constant steady-state flow rate (variance, 0.04 mL/s), whereas the other systems injected in a pulsatile fashion, with significantly greater variance (P < .001). Discussion To the authors' knowledge, this is the first reported laboratory study providing preliminary evidence of differences between the fluid delivery performance of CT injection systems. Additional investigations using a dedicated flow phantom simulating human physiological flow parameters should be conducted, and depending on the results, a clinical study could assess the effect on image quality. Conclusion The piston-based injector demonstrated higher maximum achievable flow rates and more consistent steady-state flow when compared to peristaltic pump-based injectors.