Abstract
Whether COPD is generally known as a small airway disease, recent investigations suggest that vascular remodeling could play a key role in disease progression. This paper develops a specific investigation framework in order to evaluate the remodeling of the intrapulmonary vascular network and its correlation with other image or clinical parameters (emphysema score or FEV1) in patients with smoking- or genetic- (alpha-1 antitrypsin deficiency - AATD) related COPD. The developed approach evaluates the vessel caliber distribution per lung or lung region (upper, lower, 10%- and 20%- periphery) in relation with the severity of the disease and computes a remodeling marker given by the area under the caliber distribution curve for radii less than 1.6mm, AUC16. It exploits a medial axis analysis in relation with local caliber information computed in the segmented vascular network, with values normalized with respect to the lung volume (for which a robust segmentation is developed). The first results obtained on a 34-patient database (13 COPD, 13 AATD and 8 controls) showed significant vascular remodeling for COPD and AATD versus controls, with a negative correlation with the emphysema degree for COPD, but not for AATD. Significant vascular remodeling at 20% lung periphery was found both for the severe COPD and AATD patients, but not for the moderate groups. Also the vascular remodeling in AATD did not correlate with the FEV1, nor with DLCO, which might suggest independent mechanisms for bronchial and vascular remodeling in the lung.
