Axial and multiplanar CT Analysis of Pulmonary Vasculature in COPD: Correlation with Exacerbation

초록

We hypothesized that multiplanar CT measurements of PA enlargement would be more strongly associated with exacerbation of COPD than axial CT measurements. We evaluated data from 662 subjects enrolled in the COPDGene study that were divided into three groups. We measured MPA and AA both on axial images and on multiplanar reconstructions created from the volumetric dataset, and evaluated the relationship between PA parameters and exacerbations of COPD. The MPA was measured both in its tubular portion and at the bifurcation. Univariate analysis was used to evaluate the relationship between PA diameters and exacerbation group. On axial imaging, MPA diameters for bifurcation and tubular segments and PA: AA ratios at both sites were significantly different among the exacerbation groups. On multiplanar reconstruction, the minor diameter of the MPA and PA: AA ratio at the tubular site were significantly different among the exacerbation groups. The strongest association with exacerbation was found with the axial PA:AA ratio at the tubular segment: for this measurement, the mean ratio for non-exacerbators was 0.79, compared with 0.82 for those with non-severe exacerbations, and 0.83 for those with severe exacerbations. Axial MPA diameter at the tubular site and PA: AA ratios at the tubular and bifurcation sites were significantly different between non-exacerbation and any exacerbation. Multiplanar MPA minor diameter and PA: AA ratios at the tubular site were also significantly different. Evaluation of PA: AA ratio cutoff values showed that a cutoff value of 0.8 for axial PA: AA ratio at the tubular site appeared to provide optimal separation between exacerbators and non-exacerbators. Axial measurements of the MPA diameter and PA: AA ratio are significantly different among exacerbation groups. Multiplanar measurements in general were less significant.