Comparison of in-vivo lung morphometry models from multiple b-value diffusion-weighted MRI in healthy controls, IPF and COPD patients

Introduction: Two models of gas diffusion MRI, namely the cylinder model (CM) [Yablonskiy, D. A., et al. (2002). PNAS 99(5)] and the stretched exponential model (SEM) [Parra-Robles, J., et al. (2014). Proc ISMRM:3529], have been proposed for quantitative measurement of alveolar microstructural length scales (L­m for CM and LmD for SEM) from multiple b-value hyperpolarised gas diffusion-weighted (DW) MRI.

Aims: Evaluate and compare estimates of lung morphometry from two models of 3He gas diffusion in healthy controls, idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) patients.

Methods: 46 subjects underwent multiple b-value 3He DW-MRI: 19 healthy controls, 13 IPF and 14 COPD patients. Maps of Lm and LmD values were generated using the CM and SEM respectively, and mean values for each subject were derived.

Results: A statistically significant difference (p<0.001) was obtained between healthy controls and patient groups for both mean Lm and LmD values. LmD and Lm were significantly correlated (p<0.001) in a power relationship regression fit model (R2=0.957) (Figure 1).