MR properties of F-19 C3F8 gas in the lungs of healthy volunteers: T-2* and apparent diffusion coefficient at 1.5T and T*(2) at 3T

Purpose: To measure the transverse relaxation time (T-2*) and apparent diffusion co-efficient (ADC) of F-19 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 F-19 C3F8 (eight subjects) and Xe-129 (six subjects) at 1.5T. T-2* mapping with F-19 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 F-19 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 mm(2)/s to 1.83 mm(2)/s (P = .0017) for F-19 C3F8 , and from 2.49 mm(2)/s to 3.38 mm(2)/s (P = .0015) for Xe-129. The posterior-to-anterior gradient in ADC for FRC versus TLC in the superior half of the lungs was measured as 0.0308 mm(2)/s per cm versus 0.0168 mm(2)/s per cm for F-19 C3F8 and 0.0871 mm(2)/s per cm versus 0.0326 mm(2)/s per cm for Xe-129. A consistent distribution of F-19 C3F8 T-2* values was observed in the lungs, with low values observed near the diaphragm and large pulmonary vessels. The mean T-2* 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 (T-2* and ADC) were established for C3F8 in vivo lung imaging in healthy volunteers.

Automated summary

The study measured the transverse relaxation time (T-2*) and apparent diffusion coefficient (ADC) of F-19 C3F8 gas in human lungs at 1.5T and 3T, showing a significant increase in ADC from functional residual capacity (FRC) to total lung capacity (TLC). The T-2* values of F-19 C3F8 exhibited a consistent distribution pattern in the lungs of healthy volunteers, with lower values near the diaphragm and larger pulmonary vessels.