Recently, dynamic chest radiography (DCR) was developed to evaluate pulmonary function using a flat-panel detector (FPD), which can evaluate blood flow in the pulmonary artery without injection of contrast agents. This study investigated the ability of a FPD to measure physiological changes in blood flow and to detect pulmonary embolism (PE) in monkeys.Methods and Results:DCR was performed in 5 monkeys using a FPD. Regions of interest (ROI) were placed in both lung fields of the image, and

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... um changes in pixel value (∆pixel value) in the ROI were measured during 1 electrocardiogram cardiac cycle. Next, a PE model was induced using a Swan-Ganz catheter and additional images were taken. The ∆pixel value of the lungs in normal and PE models were compared in both supine and standing positions. The lung ∆pixel value followed the same cycle as the monkey electrocardiogram. ∆pixel values in the upper lung field decreased in the standing as compared to the supine position. In the PE model, the ∆pixel value decreased in the area of pulmonary blood flow occlusion and increased in the contralateral lung as compared to the normal model (normal model 1.287±0.385, PE model occluded side 0.428±0.128, PE model non-occluded side 1.900±0.431). A FPD could detect postural changes in pulmonary blood flow and its reduction caused by pulmonary artery occlusion in a monkey model.