List the key technical points of iodine map examinations obtained by subtraction technique. Describe radiologic features of chronic pulmonary thromboembolism at iodine maps. Evaluate the diagnostic performance of iodine maps for assessment of chronic pulmonary thromboembolism.

INTRODUCTION Chronic pulmonary thromboembolism (cPE) is a consequence of incomplete resolution of acute emboli in pulmonary arteries. Physiopathology of pulmonary thromboembolism is complex and involves beyond pulmonary arteries. Nowadays, it is considered to be a manifestation of an extensive disease which encompasses deep venous system of the extremities and local mechanisms in pulmonary vasculature. Therefore, the term Venous Thromboembolic Disease (VTD) has been suggested to be more adequate. The term Venous Thromboembolic Disease includes different manifestations of the thromboembolic disease: Deep vein thrombosis (acute and...

IODINE MAPS OF THE LUNG: TECHNICAL ASPECTS There are two ways to obtain iodine maps: dual-energy and subtraction. We will focus on subtraction technique. To get perfusion maps based on subtraction technique two scans of the lungs are consecutively obtained. The first non-contrasted scan is followed by a contrast-enhanced scan. The contrast-enhanced scan is acquired using bolus tracking in the pulmonary trunk; therefore, it will be equivalent to conventional CTA. Both scans use the same scanner settings except for a lower dose in the pre-contrast...

Chronic pulmonary thromboembolism is still not well understood. The physiopathology of this disease is complex, usually beginning in lower extremities with venous blood clot formation. On final stages, after obstruction and remodeling of pulmonary arteries, pulmonary hypertension might develop. Computed tomography angiography is the “standard” diagnostic method in cPE. However, limited evaluation of small-size arteries may decrease its diagnostic capability. Iodine maps allow proper evaluation of peripheral territories, and it is outlined as a suitable technique to study pulmonary microcirculation. Combination of CT angiography and...

Pengo, V., Lensing, A. W. A., Prins, M. H., Marchiori, A., Davidson, B. L., Tiozzo, F., … Prandoni, P. (2004). Incidence of Chronic Thromboembolic Pulmonary Hypertension after Pulmonary Embolism. New England Journal of Medicine, 350(22), 2257–2264. Brink, M., Verschoor, A., Heijdra, Y., Schaefer, C., & Prokop, M. (2014). Subtraction techniques enable single-energy iodine mapping of pulmonary perfusion: An educational exhibit, 15. Ende-Verhaar YM, Cannegieter SC, Vonk Noordegraaf A, Delcroix M, Pruszczyk P, Mairuhu AT, Huisman MV, Klok FA (2017). Incidence of chronic thromboembolic pulmonary hypertension...