Computed tomographic pulmonary angiography in the assessment of severity of chronic thromboembolic pulmonary hypertension and right ventricular dysfunction

Purpose: The aim was to investigate the role of computed tomographic pulmonary angiography (CTPA) in the assessment of severity and right ventricular function in chronic thromboembolic pulmonary hypertension (CTEPH).

Materials and methods: Clinical and radiological data of 56 patients with CTEPH January 2006-October 2009 were retrospectively reviewed in the present study. All patients received CTPA with a 64-row CT using the retrospective ECG-Gated mode before digital subtraction pulmonary angiography and right-heart catheterization. CTPA findings including Right Ventricular diameter (RVd) and left ventricular diameter (LVd) were measured at the end diastole. CT Pulmonary Artery Obstruction Indexes including Qanadli Index and Mastora Index were used in the assessment of severity of pulmonary arterial obstruction. Hemodynamic parameters and pulmonary hypertension classification were evaluated by right-heart catheterization in all patients. Right ventricular function was measured with echocardiography in 49 patients.

Results: Qanadli Index and Mastora Index respectively were (37.93±14.74)% and (30.92±16.91)%, which showed a significant difference (Z=-5.983, P=0.000) and a good correlation (r=0.881, P=0.000). Neither Qanadli nor Mastora Index correlated with pulmonary hypertension classification (r=-0.009, P=0.920) or New York Heart Association heart function classification (r=-0.031, P=0.756). Neither Qanadli nor Mastora Index correlated with any echocardiographic right ventricular parameters (P>0.05), while RVd/LVd by CTPA correlated with echocardiographic right ventricular functional parameters (P<0.05). Both Qanadli (r=-0.288, P=0.006) and Mastora Index (r=-0.203, P=0.032) demonstrated a weakly negative correlation with SPO2. CTPA findings correlated with hemodynamic variables. Backward linear regression analysis revealed that the RVd/LVd, Right Ventricular Anterior Wall Thickness (RVAWT), Main Pulmonary Artery trunk diameter (MPAd) were shown to be independently associated with mean Pulmonary Artery Pressure (mPAP) levels (model: r2=0.351, P=0.025; RVd/LVd: beta=11.812, P=0.000; RVAWT: beta=2.426, P=0.000; MPAd: beta=0.677, P=0.003).

Conclusion: Computed tomographic pulmonary angiography is a valuable tool to evaluate hemodynamics, right ventricular function of CTEPH, but neither Qanadli Index nor Mastora Index can reflect pulmonary arterial obstruction in CTEPH accurately.