QCT analysis of emphysema and air trapping in coil-based lung volume reduction treatment

Abstract

Background: Degree of emphysema is believed to be associated with response to coil-based lung volume reduction (LVR) treatment. However, little is known about the impact of air trapping (AT). Objectives: To assess association of AT with reduction in residual volume (RV) Methods: 42 severe emphysema patients were treated with PneumRx coils. ΔRV%≤-10% defined positive response(18 responders). Registration-based disease probability measures (DPMs) of emphysema (DPM_EMPH) and air trapping only (DPM_AT) have shown to better discriminate these subtypes of COPD when compared to threshold-based, single scan measures of emphysema (LAA-950) and AT (LAA-856). DPM and LAA measures were computed for treated lobe using Apollo (VIDA Diagnostics, IA). Results: DPM measures yield higher correlations (r/p-value) against ΔRV% than LAA measures: DPM_EMPH(-0.31/0.046) vs. LAA-950(-0.29/0.062), DPM_AT(0.35/0.024) vs. LAA-856(-0.11/0.50). DPM_EMPH (p=0.03) is a significant predictor of ΔRV% with higher value for responders. Non-responders tend to have more DPM_AT(p=0.06) than responders. LAAs are not predictive. Figure shows DPM maps in two subjects with LUL treatment. Responder is associated with greater emphysema and limited to low AT-only tissue. Conclusions: Registration-based DPM measures are able to separate AT-only and emphysema subtypes. QCT has promise for greater prediction of response for patients undergoing coil-based LVR therapy.