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Correlation of a Scintigraphic Pulmonary Perfusion Index With Hemodynamic Parameters in Patients With Pulmonary Arterial Hypertension

Purpose To determine whether the perfusion index (PI) can be used as a noninvasive measure to diagnose and predict the severity of disease in patients with pulmonary arterial hypertension (PAH). Materials and Methods Twenty-two patients were included in this retrospective investigation: 9 controls and 13 patients with PAH. Controls had no evidence of PAH [mean pulmonary arterial pressure (MPAP) ⩽25 mm Hg and pulmonary capillary wedge pressure ⩽18 mm Hg]. The study patients had PAH (MPAP ≥25 mm Hg and pulmonary capillary wedge pressure ⩽18 mm Hg) and no diagnosis of pulmonary embolism. Due to the retrospective nature of the study, the PI was calculated from the posterior perfusion image of a ventilation perfusion scan. The PI was computed as the sum of differences versus control for the 9 deciles above background. Receiver operating characteristic curve analysis was used to compare PI with other parameters for predicting PAH. Results Linear correlations of PI were found to be significant with the following parameters: pulmonary vascular resistance (r=0.81, P=0.00009), total pulmonary vascular resistance (MPAP/cardiac output) (r=0.80, P=0.00013), pulmonary artery systolic pressure (r=0.73, P=0.00018), MPAP (r=0.72, P=0.00022), pulmonary diastolic pressure (r=0.53, P=0.01), and right atrial pressure (r=0.50, P=0.03). Using logistic regression, the PI was significant in separating patients with PAH from controls (&khgr;2=5.6, P=0.02). Conclusion The data suggest that PI can be used for the noninvasive diagnosis and measurement of severity of PAH.