Generally, in discussions of cardiovascular magnetic resonance (CMR) most authors limit their discussions to supradiaphragmatic anatomic and pathologic vascular perturbations. We, however, believe that nonthoracic aortic vasculature should also be included. The purpose of this chapter is to emphasize to the clinician that the “C” in CMR stands for cardiovascular, and therefore includes the broader vasculature and is not limited to that adjacent to, or associated with, the small beating muscle in the center of the chest. The following will be a general discussion on the utility of CMR, with and without the use of magnetic resonance angiography (MRA), to understand peripheral angiography. Over the last decade, extensive research and investigations have demonstrated the utility, applicability, and reproducibility of noninvasive imaging of the peripheral vasculature using CMR. Many specialized textbooks are dedicated to that subject alone, and this single chapter will serve to summarize the capabilities of CMR. Specifically, it is not meant to be an exhaustive compendium of all that is known. In this chapter we will not focus on specific aortic disease as an individual entity, but only as related to conduits of the branches derived from the aorta with the exception of the carotid vessels, which are not included.

Many noninvasive assessments of peripheral vascular disease exist, including ultrasound which incorporates continuous wave, pulse wave Doppler, and two-dimensional imaging; exercise testing; impedance plethsmography; and magnetic resonance imaging (MRI)/MRA. Each of these noninvasive modalities has its own advantages and disadvantages. Before the development of MRA, the only suitable method to evaluate the peripheral vasculature was contrast arteriography. Now, virtually all vascular territories can be visualized by the use of, either in combination or individually, CMR and MRA. Although this chapter will be limited to arterial structure it should be noted that there is also a role for venous and lymphatic characterization by both anatomic and flow-related techniques.

As the population continues to age, the role atherosclerosis plays cannot be overstated. Beyond affecting the coronary bed, the aorta and the carotids, there is increasing recognition that impairment of the renal arteries and peripheral runoff vessels are major sources of morbidity and mortality. Unexplained hypertension affects a significant number of patients because of occlusion of one or more renal arteries. Claudication has been recently recognized by the National Institutes of Health (NIH) as one of the major morbidities facing our aging population, and strategies aimed at detecting its presence are in general under utilized by the internist, cardiologist, and the general surgeon. Historically, a major difficulty in this assessment was a lack of a suitable imaging strategy, placing the vascular surgeon, cardiologist, and interventionalist at a disadvantage when addressing this major disabling entity. With the recognition that diabetes plays a growing role in disease presentation, either due to its increase prevalence or better recognition, the search for occult atherosclerotic disease in this population has been recognized as being critically important by leading medical societies. Peripheral arterial disease is the most common cause of systematic obstruction in the major extracoronary arteries. For the most part, the pathophysiologic understanding of this disease process is identical to that of the coronary artery tree. The risk factors for atherosclerosis of the noncoronary arteries are identical to those of coronary artery disease patients. Detection by CMR follows a similar pathway to that utilized in invasive strategies, aiming to detect pathology that exceeds 50% obstruction. In general, as the disease process progresses, luminal encroachment graded as >70% is likely to be responsible for symptomotology. Claudication, whether it is of the lower extremity or upper extremity through effort related activity, is almost always the universal presenting symptom. Intermittent claudication can be mild, progressive, and debilitating and can wax and wane.

Because the therapies for peripheral arterial disease, while still in their infancy, have generally improved over the last decade, the CMR capability to detect disease has progressed rapidly. Despite these improved imaging strategies, detection of the disease does not always lead to optimized therapy for all vascular territories. For instance, the external iliac arteries, a source of substantial debilitating buttocks claudication, are rarely intervened upon. A chief therapeutic option remains adopting conservative measures, strongly focusing on preventing progression of disease, improving exercise capability with walking, conditioning exercises, and cessation of smoking. Several pharmocologic therapies are available but have not generally resulted in dramatic improvements in symptoms. The fall-back position for patients who have failed conservative therapy is interventional vascular or surgical therapies, which have shown great promise in reducing certain morbidities and mortalities. The characteristics of CMR are ideal in detecting atherosclerosis within the peripheral vascular bed; early experimental research suggesting this may be an important modality to risk-stratify atherosclerotic plaques.