Sonography Vascular Peripheral Arterial Assessment, Protocols, and Interpretation

Excerpt

The most common disease process affecting the peripheral arterial system is atherosclerosis. Peripheral arterial disease (PAD) is a steno-occlusive process with occasional aneurysmal dilation of the involved vessels that involves over 8.5 million people in the United States. Common symptomatology from compromised peripheral arterial perfusion ranges from intermittent claudication to rest pain. As the disease process progresses, it can lead to ulceration, gangrene, and limb loss. The peripheral arterial disease more commonly involves the lower extremities. This article will evaluate lower extremity arterial disease; however, a similar approach can be applied to upper extremities.

Noninvasive physiological examinations are often the first line of testing, consisting of a physical exam, ankle-brachial index, or segmental limb pressures. Duplex ultrasonography is a complementary modality that can help confirm the diagnosis, evaluate the extent of disease, monitor progression, and identify complications.

Performing and interpreting a peripheral arterial ultrasound necessitates a sufficient understanding of the normal anatomy and caliber of arterial vessels, pathophysiology of arterial disease, and the hemodynamics of normal and abnormal flow. Moreover, the exam requires a baseline knowledge of the various ultrasonographic modalities and appropriate settings and techniques. Both the sonographer and the interpreting physician need to recognize what constitutes an adequate study.

Ultrasound (US) is widely available, exposes the patient to no ionizing radiation, is typically less expensive, and has a smaller footprint than other cross-sectional imaging modalities. Drawbacks include the poor conductivity of soundwaves through air and bone and the attenuation of sound waves as they propagate through soft tissues, particularly in patients with larger body habitus. These constraints are most pronounced for the mediastinal and visceral vasculature. Peripheral assessment, however, has its own limitations, notably in patients with extensive edema, wounds, or scarring.