Cardiac magnetic resonance imaging has emerged as a potential valuable test for the early detection of Pulmonary Arterial Hypertension. A number of reports have provided some preliminary evidence that Pulmonary Artery (PA) stiffness may be accurately detected by imaging of the pulmonary artery in order to measure PA stiffness. In addition, cardiac MRI could play provide early and effective treatment for Pulmonary Arterial Hypertension (PAH).

Inclusion Criteria:

Consecutive patients aged ≥ 18 years with PAH as dictated by a comprehensive examination and echocardiography will be included for enrollment.

Exclusion Criteria:

• Age < 18 years
• Pregnancy
• Mechanical ventilation
• Acute or chronic renal failure (creatinine clearance < 30 ml/min or requiring renal replacement therapy)
• Inability to perform MRI (i.e. claustrophobia, severe obesity (> 150 kg), device incompatible with MRI)
• Significant arrhythmia that precludes adequate ECG-gating for the MRI (i.e. atrial fibrillation with highly variable cycle lengths)
• Prior heart or lung transplantation
• Left ventricular systolic (ejection fraction < 50%) or diastolic failure (based on Framingham criteria for heart failure with preserved ejection fraction)
• Significant left-sided valvular disease (≥ moderate aortic stenosis, mitral stenosis, aortic regurgitation, mitral regurgitation) or prior valve surgery

The population will consist of a total of 90 subjects separated evenly into the following subgroups: 1) Mild PAH, 2) Moderate or Severe PAH, and 3) Normal Controls.