Upright CT reveals 18.8% drop in total pulmonary vascular volume versus supine, mainly from veins

Upright CT shows total pulmonary vascular volume falls 18.8% (99.8 vs 81.0 mL) vs supine, with a 25.4% venous decrease—double the 11.1% arterial loss—and a craniocaudal gradient.

• Standing reduced total pulmonary vascular volume by 18.8% compared with supine position (mean 99.8 ± 18.2 mL vs 81.0 ± 14.3 mL; P < .001).
• The decrease was predominantly venous: pulmonary venous volume fell 25.4% (50.7 vs 37.5 mL) versus a 11.1% arterial decrease (49.1 vs 43.6 mL; P < .001).
• Volume reductions followed a craniocaudal gradient, with even dependent lower lung regions showing a 12.0% TPVV decrease (40.4 vs 35.4 mL; P < .001).

Automated summary

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