Carotid Ultrasound Examinations Help Identify Stroke Risk

A new study concludes that carotid ultrasound is highly accurate in detecting the presence of calcified atherosclerotic lesions larger than 8 mm³, but less accurate in detecting smaller volume calcified plaques.

Researchers at Umea University (Sweden) conducted a study that analyzed 94 carotid arteries from 88 patients (mean age 70 years, 33% females) to determine the accuracy of ultrasound B mode in detecting atherosclerotic calcifications during pre-endarterectomy examinations. After the procedure, the excised plaques were quantified using cone beam computed tomography (CBCT), from which the calcification volume (in mm³) was calculated. Carotid artery calcification by the two imaging techniques was then compared using conventional correlations.

The results showed that carotid ultrasound was highly accurate in detecting calcifications, with a sensitivity of 88.2%. Based on calcification volumes as measured by CBCT, the researchers divided the plaque into four groups: less than 8; 8–35; 36–70; and over70 mm³. They found that calcification volumes larger than 8 mm³ were accurately detectable by ultrasound, with a sensitivity of 96%. Of the 21 plaques with a smaller than 8 mm³ calcification volume; only 13 were detected by ultrasound, resulting in a sensitivity of 62%. The study was published in the August 2015 issue of International Journal of Molecular Sciences.

“We know that preventive surgical treatment of carotid stenosis is only beneficial for a small subgroup, and that most asymptomatic patients will do better with only medical therapy,” said lead author Fisnik Jashari, MSc, a doctoral student in the department of public health and clinical medicine. “By using ultrasound, we can identify the patients who are at a higher risk of stroke and thus would benefit from surgery. But preventing unnecessary surgical intervention in most cases is equally important.”

Historically, carotid calcification is detected by X-ray imaging. With the development of ultrasound examination of vascular pathology, carotid two-dimensional (2D) grey scale has become a routine investigation in vascular laboratories; but while ultrasound may detect the presence of calcification, it is an accurate means for quantifying its extent, unlike CBCT, which can detect calcification volumes as small as one mm³. However, any CT investigation carries the risk of significant radiation, as well as limited availability.

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