RATIONALE AND OBJECTIVES: Pulmonary vascular control mechanisms are complex and
likely to differ between species. We wish to quantify regional perfusion and the effects of
gravity using computed tomography. MATERIALS AND METHODS: Sequential density
measurements following the administration of a bolus of iodinated contrast medium were
acquired from four healthy human subjects and four dogs. RESULTS: In humans, perfusion
(Q) was linear throughout most of the range of vertical height, with an overall gradient of …