Improving the Diagnostic Pathway of Pulmonary Hypertension using Cardio-Pulmonary Magnetic Resonance Imaging

Whilst pulmonary hypertension is a relatively uncommon condition, it is associated with a poor quality of life and poor survival. It is therefore important that we correctly identify patients who suffer from pulmonary hypertension, assess the underlying cause (an essential step for treatment) and seek those who are at risk of death. Current guidelines centre on right heart catheterisation as the recommended tool to answer these important clinical questions. Since it was first described in the mid-1950s, there have been significant improvements in the survival of patients with pulmonary hypertension, mainly due to the introduction of vasodilator therapies and surgical procedures. There have been parallel improvements in imaging technologies, the most tangible of which is cardiac MRI, allowing time resolved assessment of cardiac structure and function. Despite these improvements in non-invasive methodologies, there remains heavy reliance upon invasively measured pressures and flow for the diagnosis, phenotyping and assessment of risk in patients with pulmonary hypertension. The aim of this PhD thesis is to evaluate, and hopefully increase, the role of cardio pulmonary vascular MRI in the non-invasive assessment of pulmonary hypertension. I show that cardiac MRI metrics, particularly when combined in a regression model, are able to predict mean pulmonary arterial pressure. Such models are able to identify with reasonable accuracy the presence of pulmonary hypertension in patients referred to a tertiary referral centre. The role of cardio-pulmonary MRI in the assessment of the underlying group of pulmonary hypertension, such as chronic thrombo-embolic pulmonary hypertension and PH-left heart disease, is then explored as identification of patients who may respond to PH specific therapy is an important step. Finally, the role of MRI in the assessment of prognosis, concentrating specifically on patients with PH left heart disease and PH in patients with chronic obstructive pulmonary disease is assessed.