Computed tomography quantification of pulmonary vessels in chronic obstructive pulmonary disease as identified by 3D automated approach

Abstract

The aim of this study was to investigate the vascular alteration of the whole lung and individual lobes in patients with COPD, and assess the association between pulmonary vessels and the extent and distribution of emphysema as well as pulmonary function by a 3-dimensional automated approach.A total of 83 computed tomography images from COPD patients were analyzed. Automated computerized approach was used to measure the total number of vessels at the fifth generation. The extent of emphysema (%LAA-950) in the whole lung and individual lobes were also calculated automatically. The association between the vascular number and the extent and distribution of emphysema, as well as the pulmonary function were assessed.Both the vascular number of fifth generation in the upper lobe and in the lower lobe were significantly negatively correlated with %LAA-950 (P < 0.05). Furthermore, there were significant, yet weak correlations between the vascular number and FEV1% predicted (R = 0.556, P = 0.039) and FEV1/FVC (R = 0.538, P = 0.047). In contrast, the vascular numbers were strongly correlated with DLco (R = 0.770, P = 0.003). Finally, the vascular number correlated closer with %LAA-950 of upper lobes than with %LAA-950 of lower lobes.Pulmonary vessel alteration can be measured; it is related to the extent of emphysema rather than the distribution of emphysema.

Figure 1

Flow diagram of study population selection.

Figure 2

An example of the small vessels segmentation and measurement as well as its 3-D surface model. The original chest CT scan was shown (A); lung volume segmentation is performed before the vascular tree segmentation, and individual lobes were shown in different color (B); vessels tree (shown in different color in each lobe) and airway tree (red) were segmented and represented as 3-D surface model (C); the cross-section was located around the airway, and with the right angle to the airway center line (right upper lobe (D); the vessels in the cross-section were labeled in blue (E); the number of vessels in the cross-section were measured automatically (red star, F).

Figure 3

Schematic flowchart of the vascular segmentation algorithm.

Figure 4

A 3-D surface model of the extent and distribution of emphysema: original CT image in transverse view (A); original CT image in coronal view (B); the LAA area is highlighted in different color in each lobe (C, D). CT = computed tomography, LAA = low attenuation area.

Figure 5

The Correlation between value of TNV and pulmonary function test measurements. TNV = total number of vessels.

Figure 6

The correlation between value of TNV and the extent of emphysema. LLL = left lower lobe, LUL = left upper lobe, RLL = right lower lobe, RML = right middle lobe, RUL = right upper lobe, TNV = total number of vessels, Whole = whole lung.