Middle-aged female patient with a history of systemic sclerosis presents to her cardiologist's office with complaints of increasing fatigue, shortness of breath, and chest discomfort during physical activity. The physician suspects pulmonary hypertension and needs to accurately measure the pulmonary arterial pressure. What is the most appropriate diagnostic method for assessing pulmonary arterial pressure in this patient?
• Echocardiography
• Magnetic resonance imaging (MRI)
• Pulmonary function tests
• Right heart catheterization