MR properties of 19F C3F8 gas in the lungs of healthy volunteers: T2∗ and apparent diffusion coefficient at 1.5T and T2∗ at 3T

Abstract

Purpose: To measure the transverse relaxation time ((Formula presented.)) and apparent diffusion coefficient (ADC) of 19F-C3F8 gas in vivo in human lungs at 1.5T and 3T, and to determine the representative distribution of values of these parameters in a cohort of healthy volunteers. Methods: Mapping of ADC at lung inflation levels of functional residual capacity (FRC) and total lung capacity (TLC) was performed with inhaled 19F-C3F8 (eight subjects) and 129Xe (six subjects) at 1.5T. (Formula presented.) mapping with 19F-C3F8 was performed at 1.5T (at FRC and TLC) for 8 subjects and at 3T (at TLC for seven subjects). Results: At both FRC and TLC, the 19F-C3F8 ADC was smaller than the free diffusion coefficient demonstrating airway microstructural diffusion restriction. From FRC to TLC, the mean ADC significantly increased from 1.56 mm2/s to 1.83 mm2/s (P =.0017) for 19F-C3F8, and from 2.49 mm2/s to 3.38 mm2/s (P =.0015) for 129Xe. The posterior-to-anterior gradient in ADC for FRC versus TLC in the superior half of the lungs was measured as 0.0308 mm2/s per cm versus 0.0168 mm2/s per cm for 19F-C3F8 and 0.0871 mm2/s per cm versus 0.0326 mm2/s per cm for 129Xe. A consistent distribution of 19F-C3F8 (Formula presented.) values was observed in the lungs, with low values observed near the diaphragm and large pulmonary vessels. The mean (Formula presented.) across volunteers was 4.48 ms at FRC and 5.33 ms at TLC for 1.5T, and 3.78 ms at TLC for 3T. Conclusion: In this feasibility study, values of physiologically relevant parameters of lung microstructure measurable by MRI ((Formula presented.), and ADC) were established for C3F8 in vivo lung imaging in healthy volunteers.