Magnetic Resonance Imaging of Peripheral Vascular Disease

Peripheral vascular disease is a term often used to describe the manifestation of atherosclerosis below the bifurcation of the abdominal aorta. Peripheral atherosclerosis is a major cause of morbidity in the developed countries and 2% of adults in late middle age have intermittent claudication, which is severe enough in some patients to warrant hospital admission. The disease produces problems either by reducing blood flow or by the release of emboli from ulcerated plaques. The morphology and composition of arterial segments containing atheroma is of considerable importance. Plaques of different morphology have different effects on the arterial wall, such as the potential for thrombosis and the effect of arterial spasm. The lipid content may also affect the propensity for fissuring, ulceration, and thrombosis. In addition to discrete atherotic lesions, a localized and generalized sclerosis occurs. Sclerosis, or stiffness, can be demonstrated in experimental disease in animals and in man, and regression leads to reduced stiffness. Magnetic resonance imaging promises a comprehensive assessment of peripheral atherosclerosis noninvasively and without the use of ionizing radiation. Atheroma can be imaged directly, its size can be measured, its shape can be described, its lipid content can be assessed, and its effects upon vascular hemodynamics can be studied. In addition, arterial compliance, pulse wave velocity, and the pattern of flow within the vessel can be studied. It is thus a potential tool not only for the detection of disease but also for studying its natural history, risk factors, and the effects of pharmacological or surgical interventions.