S75 Hyperpolarised 129-xenon MRI in differentiating between fibrotic and inflammatory interstitial lung disease and assessing longitudinal change

Introduction and ObjectivesApparent diffusion coefficient (ADC) and mean diffusive length scale (LmD) are diffusion-weighted (DW) MRI measurements of alveolar gas diffusion, providing novel lung microstructure information. Hyperpolarised 129-xenon (129Xe) MR spectroscopy is a quantitative marker of gas exchange, using the ratio of uptake of 129Xe in red blood cells to tissue/plasma (RBC:TP).The objective was to evaluate hyperpolarised 129Xe MRI in differentiating between fibrotic and inflammatory ILD and assessing longitudinal change.MethodsA prospective, multicentre study of ILD patients including connective tissue disease ILD (CTD-ILD), drug induced ILD (DI-ILD), hypersensitivity pneumonitis (HP), idiopathic non-specific interstitial pneumonia (iNSIP) and idiopathic pulmonary fibrosis (IPF). Hyperpolarised 129Xe MRI was performed on a 1.5T scanner. Baseline HRCT scan was performed within a year prior to the MRI scan. Semi-quantitative visual CT analysis was performed by two consultant chest radiologists. In the non-IPF subtypes, a ground glass opacity score