Quantifying abnormal alveolar microstructure in cystic fibrosis lung disease via hyperpolarized 129 Xe diffusion MRI

• Published in: Journal of cystic fibrosis 2024-09, Vol.23 (5), p.926
• Main Authors: Bdaiwi, Abdullah S, Svoboda, Alexandra M, Murdock, Kyle E, Hendricks, Alexandra, Hossain, Md M, Kramer, Elizabeth L, Brewington, John J, Willmering, Matthew M, Woods, Jason C, Walkup, Laura L, Cleveland, Zackary I
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Child; Cystic Fibrosis - complications; Cystic Fibrosis - diagnostic imaging; Cystic Fibrosis - physiopathology; Diffusion Magnetic Resonance Imaging - methods; Female; Humans; Male; Pulmonary Alveoli - diagnostic imaging; Pulmonary Alveoli - pathology; Respiratory Function Tests - methods; Xenon Isotopes
• ISSN: 1873-5010

Cystic Fibrosis (CF) progresses through recurrent infection and inflammation, causing permanent lung function loss and airway remodeling. CT scans reveal abnormally low-density lung parenchyma in CF, but its microstructural nature remains insufficiently explored due to clinical CT limitations. To this end, diffusion-weighted Xe MRI is a non-invasive and validated measure of lung microstructure. In this work, we investigate microstructural changes in people with CF (pwCF) relative to age-matched, healthy subjects using comprehensive imaging and analysis involving pulmonary-function tests (PFTs), and Xe MRI. 38 healthy subjects (age 6-40; 17.2 ± 9.5 years) and 39 pwCF (age 6-40; 15.6 ± 8.0 years) underwent Xe-diffusion MRI and PFTs. The distribution of diffusion measurements (i.e., apparent diffusion coefficients (ADC) and morphometric parameters) was assessed via linear binning (LB). The resulting volume percentages of bins were compared between controls and pwCF. Mean ADC and morphometric parameters were also correlated with PFTs. Mean whole-lung ADC correlated significantly with age (P < 0.001) for both controls and CF, and with PFTs (P < 0.05) specifically for pwCF. Although there was no significant difference in mean ADC between controls and pwCF (P = 0.334), age-adjusted LB indicated significant voxel-level diffusion (i.e., ADC and morphometric parameters) differences in pwCF compared to controls (P < 0.05). Xe diffusion MRI revealed microstructural abnormalities in CF lung disease. Smaller microstructural size may reflect compression from overall higher lung density due to interstitial inflammation, fibrosis, or other pathological changes. While elevated microstructural size may indicate emphysema-like remodeling due to chronic inflammation and infection.