Cardiac MRI in Pulmonary Hypertension

1 BACKGROUND Currently the gold standard for evaluation of pulmonary hypertension is right heart pressure as measured by cardiac catheterization. Thus the method for stratifying patients with pulmonary hypertension in terms of risk and response to treatment is suboptimal, requiring multiple invasive procedures.

A number of studies have suggested that cardiac MR imaging is useful in the diagnosis of myocardial disease and may be related to patient prognosis in both ischemic and non-ischemic cardiomyopathy. Patients with pulmonary hypertension demonstrate post gadolinium delayed enhancement at the points of insertion of the right ventricle onto the inter-ventricular septum, and the presence of this finding has been shown to be inversely correlated with right ventricular function.

Quantitative evaluation of extracellular volume by post-gadolinium T1 relaxation time mapping (T1 mapping) and extracellular volume (ECV) mapping is used to quantify the extent of myocardial fibrosis, can detect fibrosis earlier than delayed enhancement imaging, and is particularly useful in non-ischemic or diffuse myocardial diseases. In addition, Displacement Encoding with Stimulated Echoes (DENSE) is a technique that allows quantification of tissue motion and myocardial strain, which can identify early myocardial dysfunction in patients with preserved ejection fraction, and therefore may be useful in the evaluation of myocardial function in pulmonary hypertension.

Utilization of novel cardiac MR techniques for quantitative assessment of the extent of subclinical myocardial disease in patients with pulmonary hypertension may therefore serve as a non-invasive tool to inform prognosis and surrogate biomarker to evaluate effectiveness of treatment strategies, with the potential to replace serial cardiac catheterization in these patients.

Our hypothesis is that utilization of novel cardiac MR techniques for quantitative assessment of the extent of subclinical myocardial disease in patients with pulmonary hypertension may serve as a non-invasive tool to inform prognosis and surrogate biomarker to evaluate effectiveness of treatment strategies, with the potential to replace serial cardiac catheterization in these patients.