Diagnosis of a Carotid Ultrasound
In considering carotid ultrasound, blockage of these arteries is the prime focus. Initially a history and physical exam will assign risk factors that indicate a need for further testing via imaging.
An in-depth history can tally a list of risk factors:
- Recent cognitive changes, syncope, dizziness, or TIAs (transient ischemic attacks)
- Dyslipidemia (hypercholesterolemia and high triglycerides)
- Family history of atherosclerosis, dementia, or early cardiac death
Auscultation: besides the typical vital signs that include blood pressure and pulse, listening over the carotid arteries with a stethoscope has been the crucial first clinical step in suspecting carotid disease. Any narrowing or partial obstruction will produce blood flow turbulence, heard through the stethoscope as a “bruit,” the term for this chaotic flow. Worse is hearing nothing at all, indicating the possibility of complete occlusion.
Blood tests will offer no diagnostic advantage for the detection of carotid disease or its severity, but may help explain the conditions that caused it and offer strategies for prevention of its progression.
Evaluation of the flow of blood through the carotid arteries can be from several different approaches:
- Cerebral angiography: This is the definitive method for investigating carotid artery narrowing, but it is invasive and has a small risk of neurologic complications such as stroke.
- Carotid artery duplex ultrasound: It is non-invasive, but its accuracy declines the less narrowing of the artery there is. This makes it best for severe cases.
- Magnetic resonance angiography: It is non-invasive, but is very expensive and time consuming. It is best for severe disease, becoming less accurate for moderate disease.
- CT angiography: It is accurate, but it is invasive, especially risking those with kidney disease due to the necessity of intravenous contrast.
Because of invasiveness, cost, or the time-consuming nature of more advanced testing, carotid ultrasound to assess arterial disease is usually best as a screen from which to select out those individuals for further testing with one or more of the other techniques. In cases where carotid disease is a certainty due to the presence of bruits associated with a suspicious history, ultrasound also serves as the first step in diagnosing carotid disease.