Bronchial Wall T2-Weighted MRI Signal: An Emerging Investigational Non-Ionizing Imaging Biomarker in Severe Asthma.

Severe asthma represents a major clinical challenge, accounting for disproportionate healthcare costs and morbidity despite affecting only 3-5% of patients with asthma. Traditional computed tomography (CT) can quantify bronchial wall thickening and mucus plugging, but concerns about cumulative radiation exposure limit its use for longitudinal monitoring, particularly in patients requiring frequent assessment. Recent advances in magnetic resonance imaging (MRI), specifically T2-weighted sequences combined with ultrashort echo time (UTE) imaging, have enabled quantitative assessment of bronchial wall signal intensity without ionizing radiation. Pilot studies demonstrate that bronchial wall T2-weighted MRI signal intensity (BrWall_T2-MIS) is significantly elevated in severe versus non-severe asthma, correlates with airflow obstruction and type-2 inflammatory markers, and has shown preliminary ability to predict exacerbation risk. Importantly, this biomarker may capture different pathophysiological information than CT-derived wall thickness measurements, potentially reflecting active inflammation rather than fixed remodelling. Although evidence remains preliminary and limited to single-centre studies with small sample sizes, BrWall_T2-MIS represents a promising investigational tool that could enhance phenotyping and therapeutic monitoring in the era of targeted biological therapies for severe asthma.