Identification of vascularised carotid plaques using a standardised and reproducible technique to measure ultrasound contrast uptake.

OBJECTIVES: Contrast-enhanced ultrasonography (CEUS) has been used to assess the vascularisation of carotid plaques. Our aim was to develop and validate a standardised semi-automated method for CEUS examination of plaques, and test if the technique could be used to identify vulnerable plaques.
METHODS: Study participants were a mixed population of symptomatic and asymptomatic subjects, selected if they had a plaque with height >2.5 mm and <10% acoustic shadowing. Participants received a bolus of ultrasound contrast agent and a 90-s cine-loop was captured. A Contrast Quantification Program (CQP) was developed and trained to identify extent of contrast uptake after motion correction and application of a noise reduction algorithm. The technique was validated by comparing CQP values with visual assessment of contrast uptake. CQP values were also compared with plaque echogenicity and history of clinical events.
RESULTS: CQP values correlated with a visual, 5-scale classification of contrast uptake by two blinded, experienced sonographers. Repeated contrast injections showed high reproducibility. Participants with a history of ipsilateral stroke/TIA had significantly higher CQP values than asymptomatic participants.
CONCLUSION: We present a reproducible, semi-automatic method to identify vascularisation of carotid plaques, which could be used in prospective studies to determine the clinical value of plaque vascularisation.