A comparative study of color Doppler imaging and contrast-enhanced ultrasound for the detection of ulceration in patients with carotid atherosclerotic disease

Objectives: To evaluate the diagnostic accuracy of color Doppler imaging (CDI) and contrast-enhanced ultrasound (CEUS) for diagnosing carotid ulceration, having multi-detector computed tomography angiography (MDCTA) as the reference method.

Methods: Patients with carotid disease referred for ultrasound (US), either due to the occurrence of neurovascular symptoms or for screening purposes, were included in this study if at least one plaque causing moderate (50-69%) or severe (70-99%) internal carotid artery stenosis was detected. Carotid US with CDI technique, CEUS, and MDCTA were performed in all patients, investigating the presence of ulceration. The agreement between modalities was evaluated using kappa statistics.

Results: The study population included 54 patients (median age 62 years, inter-quartile range 16.2) and 66 carotid arteries. The mean degree of stenosis was 68.5% (SD 12.2%) while 47.1% of plaques were symptomatic. MDCTA characterized 28.8% of plaques as smooth, 45.5% irregular, and 24.3% ulcerated. Flow reversal was detected with CDI in 65.5% of ulcerations, while swirling of the microbubbles and neovessels adjacent to the ulcer were detected with CEUS in 17.64%. The agreement for ulceration diagnosis was moderate between CDI and CEUS (kappa 0.473) and between CDI and MDCTA (kappa 0.473) and very good between CEUS and MDCTA (kappa 0.921). The sensitivity, specificity, and positive and negative predictive values of CDI for the diagnosis of ulceration were 41.2%, 97.95%, 87.5%, 82.8% respectively, while CEUS respective measures were 94.1%, 97.95%, 94.1%, and 97.95%.

Conclusion: CEUS outperformed CDI in terms of agreement with MDCTA and diagnostic accuracy for the diagnosis of ulcerated carotid plaque.

Key points: • Superficial ulceration is a significant feature of carotid plaque vulnerability. • Color Doppler imaging has the potential to demonstrate carotid plaque ulceration but is characterized by limited sensitivity and moderate agreement with the reference method of multi-detector computed tomography angiography. • Contrast-enhanced ultrasound outperforms color Doppler imaging in terms of sensitivity for the detection of carotid plaque ulceration and in agreement with the reference method of multi-detector computed tomography angiography.