The field of interventional radiology in the thorax is broad and includes both percutaneous and endovascular interventions. Measurements are primarily dedicated to endovascular intervention. Endovascular interventional radiology involves the right (superior vena cava (SVC) and pulmonary arteries) or left (bronchial and non-bronchial systemic arteries) circulation. A major purpose of this chapter is to clarify the normal and abnormal size of these vascular structures from the perspective of the interventional radiologist. The aorta will be treated in a separate chapter (see Chapter by Sara Boccallini).