[Imaging tests in chronic thromboembolic pulmonary hypertension]

Imaging tests are the cornerstone of the diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH). A series of imaging tests of unquestionable utility is currently available: ventilation-perfusion scintigraphy, echocardiography, multislice computed tomography (CT), magnetic resonance imaging, and pulmonary arteriography. However, not all of these techniques are routinely indicated in all patients. Scintigraphy and echography are used to screen for CTEPH after an acute pulmonary thromboembolism. Multidetector CT is effective in the study of CTEPH since this procedure reveals the localization, extension and characteristics of the central and peripheral arterial thrombi as well as providing data on the vessel distal to the obstruction. Other findings that can affect medical or surgical treatment can be assessed with this technique, such as collateral systemic circulation, concurrent parenchymatous abnormalities, and coronary or cardiac disease. Multidetector CT is a non-invasive method that is well tolerated by patients and consequently can be used in the follow-up of the disease or to evaluate postsurgical results. Pulmonary arteriography predated other imaging techniques and was the technique of choice for the diagnosis of CTEPH for many years. Because of limited access to this procedure, a low but nevertheless present risk, and the development of non-invasive diagnostic techniques, mainly multidetector CT, the main indication of pulmonary arteriography is currently assessment of surgical accessibility in candidates for pulmonary thromboendarterectomy. When performed by expert hemodynamists using a standardized technique in the hemodynamic laboratory, this procedure is safe even in patients with severe pulmonary hypertension.