Reynolds, S., et al., Fully MR-Compatible Syringe Pump for the Controllable Injection of Hyperpolarized Substrate in Animals. Appl. Magn. Reson., 2012. 43(1): p. 263-273.
A major application of dynamic nuclear polarization has been in the study of the conversion of hyperpolarized 13 C 1 -pyruvate to lactate in various disease models. In a typical experimental protocol, hyperpolarized pyruvate is converted from solid to liquid state with superheated fluid and collected in a receiving vessel. The hyperpolarized solution is then rapidly transferred by hand from the polarizer to the imaging magnet, where it is manually injected through an intravenous cannula into the test subject by an experienced operator. Such a procedure leads to inconsistencies in timing, injection rate and volume, all of which can influence the time resolved signal as the pyruvate is metabolized. We have developed a fully magnetic-resonance-compatible withdraw/infuse syringe pump made entirely of plastic so that it can be operated within the bore of an unshielded 7 T (310 mm) magnet. The injector can be programed for variable injection volumes and rates to permit the rapid and reproducible injection of hyperpolarized material without human intervention. The injector was designed for use with 1 ml or 3 ml syringes with a maximum delivery volume of 2.4 ml. The standard deviation of delivered volume from the desired volume was found to be 0.7 % across a volume range of 0.6–2.4 ml.