Helium3 polarization using spin exchange technique: application to simultaneous pulmonary ventilation/perfusion imaging in small animals.
RATIONALE AND OBJECTIVES: To develop a simple and robust helium3 polarization system dedicated to small animal imaging. To demonstrate the potential of helium3 imaging for pulmonary ventilation and perfusion studies. METHODS: A home-built polarization system based on spin-exchange technique was used. This system was applied for magnetic resonance imaging ventilation studies on rats using a 2-T magnet. Projection-reconstruction sequences combined with the sliding-window technique were used for acquisition of high temporal resolution ventilation images. RESULTS: Helium3 polarization levels up to 25% were obtained. Simultaneous ventilation and lung perfusion images were acquired with intravenous injection of superparamagnetic contrast agents. Dose effects were investigated using several contrast agent concentration values. CONCLUSIONS: A tabletop helium3 polarization system was realized. This equipment, which is easy to operate, allows the production of polarized gas appropriate to the requirements of small animal studies. This polarization system was used successfully on a ventilation/perfusion imaging study using intravascular contrast agent.