Imaging in pulmonary hypertension: the role of MR and CT

Pulmonary hypertension (PH) is a debilitating disease with many causes that has a significant impact on quality of life and results in premature death. Until recently imaging has only played an adjunctive role to primary diagnostic modalities such as echocardiography and right heart catheterization in identifying these patients. The advent of newer imaging techniques and developments in hardware has opened up a new scope for imaging. CT offers excellent structural detail while MRI provides superb functional information without the risk of radiation. These modalities now offer a robust and in-depth diagnostic approach for the investigation of patients with suspected pulmonary hypertension. This document explores the role of MR and CT imaging methods in investigating patients with pulmonary vascular disease and different aspect of lung disease. In particular, subgroups of pulmonary hypertension associated with unique morphological changes have been closely scrutinized. In this work the value of MR angiography in patients suspected with chronic thromboembolic pulmonary hypertension or unexplained PH has been explored and in the same subgroup of patients, the role of 3D MR lung perfusion as a diagnostic tool has also been demonstrated. This research has also shown that the thoracic CT offers valuable prognostic information and imaging characteristics in patients with each of the major subcategories of pulmonary arterial hypertension. Furthermore, the diagnostic accuracy and prognostic significance of MR and CT indices for the detection of PH in patients with connective tissue disease associated with PH has been highlighted. Finally, the feasibility and diagnostic quality of MRI to identify structural parenchymal lung changes have also been analysed and this study demonstrates the potential clinical utility of imaging high risk patients with MRI in longitudinal studies thereby avoiding the hazards of radiation exposure.