Purpose: To test the reliability of potentially new computed tomographic (CT) indicators of pulmonary hypertension (PH) and to establish whether a combination of CT and echocardiographic measurements was more predictive of PH than either test alone.
Materials and methods: The institutional review board approved this retrospective study; patient consent was not required. Seventy-seven patients undergoing right-sided heart catheterization were examined. CT diameters of the main pulmonary artery, ascending aorta, and thoracic vertebra and cross-sectional area of the main pulmonary artery were measured. Segmental and subsegmental arterial diameters were recorded, and segmental artery size was compared with adjacent bronchus size by using a semiquantitative scoring system. The relationship between CT measurements and mean pulmonary arterial pressure (mPAP) was tested with linear regression. Multivariate regression was used to establish a composite index of mPAP by using CT markers of PH with echocardiography-derived right ventricular systolic pressure (RVSP). Post hoc logistic regression and receiver operating characteristic curve analysis were performed to test the diagnostic ability of the CT-echocardiography composite.
Results: The ratios of the diameter of the main pulmonary artery to the diameter of the ascending aorta (R(2) = 0.45; P < .001) and of the cross-sectional area of the pulmonary artery to the diameter of the ascending aorta (R(2) = 0.45; P < .001) correlated equally with mPAP. The ratio of the diameter of the main pulmonary artery to the diameter of the thoracic vertebra, the segmental arterial diameter, and the segmental artery-to-bronchus ratio were related to mPAP but did not strengthen correlations compared with the ratio of the diameter of the main pulmonary artery to the diameter of the ascending aorta alone. A composite index of the ratio of the diameter of the main pulmonary artery to the diameter of the ascending aorta and echocardiography-derived RVSP was more strongly related (R(2) = 0.55) to mPAP and was more significantly predictive of PH than either measure alone.
Conclusion: A combination of CT and echocardiographic markers of PH is more closely related to mPAP than either test in isolation.