Introduction
This topic covers how imaging detects and characterises diseases of the aorta and the peripheral arteries and veins: atherosclerosis and aneurysm, congenital coarctation, inflammatory aortitis, peripheral arterial occlusive disease, and venous thrombosis and varicose veins. Acute emergencies such as aortic rupture, dissection and pulmonary embolism are covered in topic 19.
Imaging methods of the vascular system
Plain radiography shows only indirect signs of vascular disease, such as wall calcification. Definitive assessment depends on duplex ultrasound, cross-sectional angiography or catheter angiography.
Atherosclerosis and aneurysm of the aorta
An aortic aneurysm is a localised dilatation of the vessel, usually defined for the infrarenal abdominal aorta as an anteroposterior diameter of 3 cm or more, or a dilatation of more than 50 percent compared with the expected normal diameter. Most are degenerative and atherosclerotic, and risk factors include male sex, age over 65, smoking and hypertension.
- Plain film: curvilinear calcification of the aortic wall, sometimes seen as a rim outlining the aorta.
- Ultrasound: screening test for the abdominal aorta; measures the anteroposterior and transverse diameters and shows mural thrombus.
- CT angiography: the key study before repair; it defines diameter, length, neck anatomy, iliac involvement, calcification and thrombus.
- Follow-up: growth of more than about 1 cm per year, or a diameter approaching the surgical threshold of roughly 5.5 cm, prompts intervention. Rupture is discussed in topic 19.