Accuracy of carotid plaque detection and intima-media thickness measurement with ultrasonography in routine clinical practice

Abstract

Background: Current guidelines in cardiovascular disease prevention advocate the use of carotid ultrasound measurements for risk stratification. Carotid abnormalities (plaques or increased intima-media thickness (IMT)) are associated with high risk of coronary and peripheral artery disease. An office-based measurement by clinicians would considerably broaden the clinical applicability of carotid ultrasound. In the present study we have assessed the accuracy of ultrasound detection of carotid plaques and intima-media thickness by trained internists in a routine outpatient setting.

Methods and results: Carotid ultrasound was performed in 112 vascular outpatients by internists, after a six-week training period. The internists' results were independently compared to the reference standard, consisting of carotid ultrasound performed in a specialized vascular laboratory. Sensitivity and specificity were calculated for plaque detection and IMT determination. The mean time required to perform the scans on the outpatient department was 7.3 min (range 4.5 to 16.7 min). A high level of accuracy for detecting plaques (sensitivity 78.5%; specificity 93.6%) was achieved. Identifying abnormal IMT had lower sensitivity but adequate specificity of 46.7% and 87.6%, respectively.

Conclusions: In conclusion, our findings demonstrate that clinicians can be trained well enough in six weeks to accurately and efficiently detect carotid plaques in an outpatient setting. IMT abnormalities were less accurately detected in the office-based approach and may require a specialized vascular laboratory.