METHODS: 85 patients who had taken chest CT and right heart catheterization (RHC) were recruited. The pulmonary arterial systolic pressure (PASP), pulmonary arterial diastolic pressure (PADP) and MPAP of each subject were measured and recorded by right heart catheterization (RHC). The diameters of the ascending aorta (dAA), descending aorta (dDA) and main pulmonary artery (dMPA), Cobb angle, diameters of right ventricle (dRV), diameters of left ventricle (dLV) were measured by means of chest CT scans. Systolic blood pressure (SBP) was measured using electronic sphygmomanometer. A linear regression equation was generated in 56 patients to estimate PAP based on chest CT values, 29 patients were used to test the accuracy of the formula.