Free-breathing Pulmonary 1H and Hyperpolarized 3He MRI: Comparison in COPD and Bronchiectasis

Abstract

In this proof-of-concept demonstration, we aimed to quantitatively and qualitatively compare pulmonary ventilation abnormalities derived from Fourier decomposition of free-breathing (1)H magnetic resonance imaging (FDMRI) to hyperpolarized (3)He MRI in subjects with chronic obstructive pulmonary disease (COPD) and bronchiectasis. All subjects provided written informed consent to a protocol approved by a local research ethics board and Health, Canada, and they underwent MRI, computed tomography (CT), spirometry, and plethysmography during a single 2-hour visit. Semiautomated segmentation was used to generate ventilation defect measurements derived from FDMRI and (3)He MRI, and these were compared using analysis of variance and Pearson correlations. Twenty-six subjects were evaluated including 12 COPD subjects (67 ± 9years) and 14 bronchiectasis subjects (70±11years). For COPD subjects, FDMRI and (3)He MRI ventilation defect percent (VDP) was 7±6% and 24±14%, respectively (P<.001; bias=-16±9%). In COPD subjects, FDMRI was significantly correlated with (3)He MRI VDP (r=.88; P=.0001), (3)He MRI apparent diffusion coefficient (r=.71; P<.05), airways resistance (r=.60; P<.05), and RA950 (r=.80; P<.01). In subjects with bronchiectasis, FDMRI VDP (5±3%) and (3)He MRI VDP (18±9%) were significantly different (P<.001) and not correlated (P>.05). The Dice similarity coefficient (DSC) for FDMRI and (3)He MRI ventilation was 86±7% for COPD and 86±4% for bronchiectasis subjects (P>.05); the DSC for FDMRI ventilation defects and CT RA950 was 19±20% in COPD and 2±3% in bronchiectasis subjects (P<.01). FDMRI and (3)He MRI VDP were strongly related in COPD but not in bronchiectasis subjects. In COPD only, FDMRI ventilation defects were spatially related with (3)He ventilation defects and emphysema.