Sex‐related differences in pulmonary vascular volume distribution

Abstract Pulmonary arterial hypertension affects females more frequently than males, and there are known sex‐related differences in the lungs. However, normal sex‐related differences in pulmonary vascular structure remain incompletely described. We aimed to contrast computed tomography‐derived pulmonary vascular volume and its distribution within the lungs of healthy adult females and males. From the CanCOLD Study, we retrospectively identified healthy never‐smokers. We analyzed full‐inspiration computed tomography images, using vessel and airway segmentation to generate pulmonary vessel volume, vessel counts, and airway counts. Vessels were classified by cross‐sectional area >10, 5–10, and <5 mm 2 into bins, with volume summed within each area bin and in total. We included 46 females and 36 males (62 ± 9 years old). Females had lower total lung volume, total airway counts, total vessel counts, and total vessel volume (117 ± 31 vs. 164 ± 28 mL) versus males (all p < 0.001). Females also had lower vessel volume >10 mm 2 (14 ± 8 vs. 27 ± 9 mL), vessel volume 5–10 mm 2 (35 ± 11 vs. 55 ± 10 mL), and vessel volume <5 mm 2 (68 ± 18 vs. 82 ± 19 mL) (all p < 0.001). Normalized to total vessel volume, vessel volume >10 mm 2 (11 ± 4 vs. 16 ± 4%, p < 0.001) and 5–10 mm 2 (30 ± 6 vs. 34 ± 5%, p = 0.001) remained lower in females but vessel volume <5 mm 2 relative to total volume was 18% higher (59 ± 8 vs. 50 ± 7%, p < 0.001). Among healthy older adults, pulmonary vessel volume is distributed into smaller vessels in females versus males.