Ratio of the Bronchial Lumen to Pulmonary Artery Diameter in Rhesus Macaques (Macaca mulatta) without Clinical Pulmonary Disease

Abstract

In human medicine, CT is widely used to detect changes in bronchial luminal diameter. The diameter of the artery that runs adjacent to the bronchus does not change dramatically along the airway path, such that this artery can be used as a reference to detect changes in the bronchial luminal diameter. The bronchoarterial ratio is increasingly used in veterinary medicine for the detection of lower airway diseases in animals. The purpose of this study was to establish the bronchoarterial ratio in rhesus macaques. We used CT to evaluate 12 rhesus macaques (Macaca mulatta) without clinical signs of pulmonary diseases and measured the bronchoarterial ratio in the right and left superior, middle, inferior and cardiac lung lobes. The overall bronchoarterial ratio (mean ± 1 SD) at all 7 locations in the 12 macaques was 0.59 ± 0.05. Moreover, there was no correlation between the BA ratio and age or sex in the study population. However, the BA ratio and weight of animals showed positive linear correlation. In this study, we established the reference range for the bronchoarterial ratio in clinically healthy rhesus macaques. This ratio is consistent among lung lobes and between animals.

Figure 1.

Cross-sectional immediate post-contrast CT image (pulmonary window) of a rhesus macaque lung at the level of the T8 vertebra, demonstrating the method for measuriing the bronchoarterial ratio in the right inferior lung lobe in cross-sectional orientation. The internal diameter of the bronchus is indicated by the white arrows, and the total diameter of the artery is indicated by the black arrows. This ratio is 0.59.

Figure 2.

Cross-sectional immediate post-contrast CT image (pulmonary window) of a rhesus macaque lung at the level of the T6 vertebra, demonstrating the method for measuring the bronchoarterial ratio in the right middle lung lobe in longitudinal orientation. The internal diameter of the bronchus is indicated by the white arrows, and the total diameter of the artery is indicated by the black arrows. This ratio is 0.61.

Figure 3.

Box-and-whisker plot of the bronchoarterial ratio for each lung lobe (7 locations) in 12 rhesus macaques without clinical respiratory disease. red *, maximum outlier; purple *, minimum outlier.