Imaging in chronic thromboembolic pulmonary disease: Current practice and advances

Chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) occurs when thromboemboli in pulmonary arteries fail to resolve completely. Pulmonary artery obstructions due to chronic thrombi and secondary microvasculopathy can increase pulmonary arterial pressure and resistance leading to chronic thromboembolic PH (CTEPH). Mechanical interventions and/or PH medications can improve cardiopulmonary haemodynamic, alleviate symptoms, and decrease mortality risk. Imaging is pivotal throughout the CTEPD management journey, spanning diagnosis, treatment planning, and assessing treatment outcome. With just computed tomography (CT) pulmonary angiogram and right heart catheterisation, an experienced multidisciplinary team can determine surgical candidacy in most cases. Dual energy CT, lung subtraction iodine mapping CT, and dynamic contrast-enhanced magnetic resonance imaging (MRI) offer comparable sensitivities with ventilation-perfusion scintigraphy in diagnosing CTEPD. Pulmonary angiogram with digital subtraction angiography although considered the gold standard for assessing thrombi extent and vasculature morphology is now mostly used to assess targets for balloon pulmonary angioplasty. Advancements in CT modalities and innovative MRI metrics offer better insight into CTEPD management but are limited by the availability of technology and expertise. Learning from current artificial intelligence application in medical imaging, there is promise in tapping the wealth of data provided by CTEPD imaging through automating cardiopulmonary and vascular morphology analysis.