Comparison of the Diagnostic Utility of Cardiac Magnetic Resonance Imaging, Computed Tomography, and Echocardiography in Assessment of Suspected Pulmonary Arterial Hypertension in Patients with Connective Tissue Disease
The Journal of Rheumatology, 05/16/2012
Clinical Article
Rajaram S et al. – In patients with connective tissue diseases (CTD) and suspected Pulmonary arterial hypertension (PAH), cardiac magnetic resonance imaging (MRI) and echocardiography have greater diagnostic utility than computed tomography (CT) in the assessment of patients with suspected PAH, and MRI has prognostic value.
Methods- In total, 81 consecutive patients with CTD and suspected PH underwent cardiac MRI, CT, and right heart catheterization (RHC) within 48 hours.
- Functional cardiac MRI variables [ventricle areas and ratios, delayed myocardial enhancement, position of the interventricular septum, right ventricular mass, ventricular mass index (VMI), and pulmonary artery distensibility] were all evaluated.
- The pulmonary artery size, pulmonary artery/aortic ratio (PA/Ao), left and right ventricular (RV) diameter ratio, RV wall thickness, and grade of tricuspid regurgitation were measured on CT.
- Tricuspid gradient (TG) and size of the RV were assessed using echocardiography.
- In the study of 81 patients with CTD, 55 had PAH, 22 had no PH, and 4 had PH owing to left heart disease.
- There was good correlation between mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) measured by RHC and VMI derived from MRI (mPAP, r = 0.69, p < 0.001; PVR, r = 0.78, p < 0.001) and systolic area ratio (mPAP, r = 0.69, p < 0.001; PVR, r = 0.68, p < 0.001) and TG derived from echocardiography (mPAP, r = 0.84, p < 0.001; PVR, r = 0.76, p < 0.001).
- In contrast, CT measures showed only moderate correlation. MRI and echocardiography each performed better as a diagnostic test for PAH than CT–derived measures: VMI ≥ 0.45 had a sensitivity of 85% and specificity 82%; and TG ≥ 40 mm Hg had a sensitivity of 86% and specificity 82%.
- Univariate Cox regression analysis showed the MRI measurements were better at predicting mortality.
- Patients with RV end diastolic volume < 135 ml had a better prognosis than those with a value > 135 ml, with a 1–year survival of 95% versus 66%, respectively.
