Abstract Rationale Ventilation heterogeneity (V˙H), or non-uniform airflow distribution, is a hallmark of asthma that reflects airway inflammation, remodeling, and disease severity. Although biologic therapies targeting type 2 (T2) inflammation improve outcomes, treatment response remains variable, and current biomarkers (i.e., circulating eosinophils, FeNO) often fail to detect residual disease. Physiological testing and imaging could offer a more direct assessment of disease activity and help guide biologic therapy selection or class switching. However, conventional measures of global V˙H, such as lung clearance index and impulse oscillometry (IOS), cannot localize dysfunction or capture regional changes with treatment. X-ray velocimetry (XV) is a novel, FDA-approved, low-dose fluoroscopic imaging technique that quantifies regional ventilation by tracking lung tissue motion during tidal breathing. We hypothesized that by reflecting airway disease severity, XV-derived V˙H correlates with asthma control. Methods In this cross-sectional pilot study, 18 adults with physician-diagnosed asthma and no spirometric obstruction at the time of exam, underwent pulmonary function testing, fluoroscopic XV imaging, and completed the Asthma Control Test (ACT). XV-derived mean specific ventilation (MSV) was calculated as the volume change of a lung region since the start of inspiration, and segmental analysis was performed. MSV/Percentage Volume was calculated for each segment and normalized as the average percentile distance from the median. Results Participants had a mean age of 38 ± 17 years and mean FEV₁ of 3.0 ± 0.8 L. The mean ACT score was 18.3 ± 4.4. Average V˙H was 0.22 ± 0.06 by MSV/Percentage Volume. Greater V˙H was significantly associated with lower ACT scores (p 0.05), indicating worse asthma control Figure 1. Conclusions XV detected regional V˙H in adults with asthma. V˙H correlated with asthma control and reflected evidence of small airways dysfunction. These findings support XV as a non-invasive functional imaging biomarker of persistent regional airflow abnormalities. Future studies will assess whether treatment-driven reductions in XV-derived V˙H correspond to improved asthma control. This abstract is funded by: None
Persaud et al. (Fri,) studied this question.