A dedicated automated injection system for dynamic contrast‐enhanced MRI experiments in mice

Abstract

Purpose To develop a reproducible small-animal dynamic contrast-enhanced (DCE) MRI set-up for mice through which volumes <100μL can be accurately and safely injected and to test this set-up via DCE measurements in resting muscle and tumor tissue. Materials and Methods The contrast agent (CA) injection system comprised 2 MR-compatible syringe pumps placed 50cm from the 7T magnet bore where the fringe field is about 40mT. Microbore tubing and T-connector, close to the injection site, minimized dead volume (<10μL). For DCE-MRI measurements in 8 CB-17 SCID mice with 1500–2500mm3 large orthotopic neuroblastoma, a bolus of 10-fold-diluted Gd-DTPA CA solution (0.1mmol/kg) was delivered (5μL/s), followed by a 50μL saline flush. Retro-orbital injections were given instead of tail vein injections, since the peripheral vasculature was reduced because of large tumor burden. Results The CA injection was successful in 19 of 24 experiments. Optical assessment showed minimal dispersion of ink-colored CA bolus. Mean (±SD) pharmacokinetic parameters retrieved from DCE-MRI examinations in resting muscle (Ktrans=0.038±0.025min−1, kep=0.66±0.48min−1, ve=0.060±0.014, vp=0.033±0.021) and tumor (Ktrans=0.082±0.071min−1, kep=0.82±0.80min−1, ve=0.121±0.075, vp=0.093±0.051) agreed with those reported previously. Conclusion We successfully designed and implemented a DCE-MRI set-up system with short injection lines and low dead volume. The system can be used at any field strength with the syringe pumps placed at a sufficiently low fringe field (<40mT).

Flushing effect of micro-bolus pulse injection and its potential impact on peripheral veins under hemostasis

“…[ 9 ] To further improve the flushing efficiency, some studies have tried and demonstrated that the flushing efficiency can be improved by shortening the pause time. [ 11 , 13 ] However, the purpose of pulse flushing is to remove solid deposits or biofilms in the pipeline. This study attempts to apply pulse flushing to pipeline-based small-volume radiopharmaceuticals bolus injection to increase the initial concentration of the drug when it enters the vein.…”

“…Sedlacik et al’s research reflected the change of injection concentration by applying a blue ink dye contrast agent, injecting the same volume onto several blotting papers, and obtaining and converting the color intensity value of blue ink on the blotting paper . [ 13 ] This method converts color information into concentration information. In this study, the programmable pulse injection device was used as the power source.…”

Non-Invasive Evaluation of Cerebral Microvasculature Using Pre-Clinical MRI: Principles, Advantages and Limitations

“…Additional problems can arise due to the difficulty and lack of standardization of the contrast agent injection in rodents [ 65 ]. The administration of the contrast agent is typically performed through injection in the jugular vein or tail vein, which is often challenging.…”