19 F MRI of human lungs at 0.5 Tesla using octafluorocyclobutane.

Abstract

The aim of this study was to demonstrate the feasibility of fluorine-19 (19 F) MRI of the human lungs using octafluorocyclobutane (OFCB, C4 F8 ). This gas has 8 magnetically equivalent fluorine nuclei and relatively long T1 and T2 (˜50 ms), which render it suitable as an MRI contrast agent. Previous experiments in small laboratory animals showed that OFCB could be successfully used as an alternative to the gases often used for 19 F MRI (sulfur hexafluoride and perfluoropropane). One male volunteer participated in this study. Immediately before an MRI scan, the volunteer inhaled the gas mixture-80% OFCB with 20% oxygen-and held his breath. Experiments were performed on a 0.5T whole-body MR scanner with a customized transmit-receive coil tuned at 19 F frequency. Fast spin echo in 2D and 3D modes was used for image acquisition. 2D images were obtained with in-plane resolution of 10 × 10 mm2 without slice selection. 3D images were obtained with the voxel size of 10 × 10 × 30 mm2 . Breath-hold duration was 20 s for 2D and 40 s for 3D imaging, respectively. Anatomically consistent 19 F MR images of the human lungs were obtained with SNR around 50 in 2D mode and 20 in 3D mode. 3D volumetric images of the lungs were reconstructed and provided physiologically reasonable volume estimates. The application of OFCB enables informative 19 F lung imaging even at low magnetic field strengths. The OFCB gas shows promise as an inhalable contrast agent for fluorine lung MRI and has a potential for clinical translation.