Technical note: 3D-printed MRI-compatible syringe pump.

Abstract

A power injector is typically employed to deliver a contrast agent to a subject (e.g., humans, animals, phantoms) during MRI, but it is costly and cannot inject more than one subject at a time. Conventional syringe pumps housing multiple syringes are typically non-MRI compatible and, thus, should be placed outside the MRI room. To develop the prototype of a cost-effective, easy-to-use, reliable syringe pump that could be deployed inside a clinical MRI bore and operated on during a scan. The MRI-compatible syringe pump (MSP) was designed using Solidworks 3D modeling software and fabricated using a Raise3D Pro2 Printer. The MSP was designed to infuse up to three syringes simultaneously. The injection speed was mainly controlled with different gear sets in the escapement unit and further adjusted by changing the effective hairspring length via a pinch pin. The MSP was evaluated with three gear sets (gear ratios: 0.20:1, 0.56:1, and 1.09:1) and 10 different effective hairspring lengths at each gear ratio. A video was recorded while operating MSP at each injection speed to calculate the volume injection rate of a 5-mL syringe (mL/s). The MSP was operated five times repeatedly at each injection speed, and the mean and standard deviation of the volume injection rate were calculated. The volume injection rates produced by three gear ratios (0.20:1, 0.56:1, and 1.09:1) were 0.209±0.003mL/s, 0.411±0.002mL/s, and 0.625±0.006mL/s, respectively, at the full hairspring length. The injection rates of gear set 1 (gear ratio: 0.20:1) decreased from 0.273±0.001mL/s to 0.245±0.001mL/s with a decrement of 0.003mL/s for 10 different effective hairspring lengths (r=0.997, p<0.001). The injection rates of gear set 2 (gear ratio: 0.56:1) decreased from 0.519±0.003mL/s to 0.469±0.003mL/s with a decrement of 0.006mL/s (r=0.987, p<0.001), and that of gear set 3 (gear ratio: 1.09:1) decreased from 0.779±0.012mL/s to 0.709±0.005mL/s with a decrement of 0.007mL/s (r=0.963, p<0.001). The coefficient of variation in the injection rate measurement was 0.727±0.346%. The MSP is a portable device that can reliably deliver a liquid agent to multiple subjects inside a clinical MRI bore during a scan.