Pulmonary Ultrashort Echo Time19F MR Imaging with Inhaled Fluorinated Gas Mixtures in Healthy Volunteers: Feasibility

To perform static breath-hold fluorine 19 ((19)F) three-dimensional (3D) ultrashort echo time (UTE) magnetic resonance (MR) imaging of the lungs in healthy volunteers by using a mixture of 79% perfluoropropane (PFP) and 21% O2.This study protocol was approved by the local research ethics board and by Health Canada. All volunteers provided written informed consent. Ten healthy volunteers underwent MR imaging at 3.0 T. Fluorine 19 3D UTE MR images were acquired during a 15-second breath hold according to one of two breathing protocols: protocol A, a 1-L inhalation of a mixture of 79% PFP and 21% O2, and protocol B, continuous breathing from a 5-L bag of a mixture of 79% PFP and 21% O2 followed by a 1-L inhalation of the same PFP-O2 mixture from a separate bag and a subsequent breath hold. The signal-to-noise ratio (SNR) was measured in the three most central image sections and was compared between breathing protocols by using an unpaired t test.Overall, the SNR was significantly greater for breathing protocol B (continuous breathing) than for breathing protocol A (single breath) (P = .018). The mean SNRs were 18 ± 6 (standard deviation) and 32 ± 6 for images acquired by using breathing protocols A and B, respectively. Breathing protocol B improves SNR by "washing out" the air from the lungs and increasing the PFP concentration prior to (19)F imaging.This study demonstrates the feasibility of (19)F 3D UTE static breath-hold MR imaging of human lungs with inert fluorinated gases.