The role of contrast-enhanced ultrasound (CEUS) in visualizing atherosclerotic carotid plaque vulnerability: Which injection protocol? Which scanning technique?

Purpose: To correlate the degree of plaque vulnerability as determined by contrast-enhancedultrasound(CEUS)with histological findings. Secondary objectives were to optimize the CEUS acquisition technique and image evaluation methods. Materials and methods: Fifty consecutive patients,either symptomatic and asymptomatic referring to our department in order to perform carotid endarterectomy(TEA),were enrolled.Each patient provided informed consent before undergoing CEUS.Ultrasound examination was performed using high-frequency (8–14 MHz)linear probe and a non-linear pulse inversion technique(mechanicalindex:0.09–1.3).A double contrast media injection(Sonovue,2mLand4mL;Bracco,Italy)was performed.Two video- tapes were recorded for every injection:early “dynamic” phase and late “flash” phase,performed with 6 high mechanical index impulses.Movies were quantitatively and qualitatively evaluated.Qualitative and quantitative evaluation were statistically compared to immunohistological diagnosis of vulnerable plaque, considered as gold standard. Results: Qualitative CEUS evaluation obtained high statistical results when compared to immunohisto- logical results,with values of sensitivity,specificity,positive predictive value(PPV),negative predictive value (NPV),and diagnostic accuracy of 94%,68%,87%,85% and 86%,respectively,which became higher if considering only asymptomatic patient,with a NPV of 91%.Nevertheless, quantitative software evaluation proved less effective and could not reach similar results. Conclusion: Carotid plaque enhancement assessed with CEUS well correlates with histological assessment of plaque instability.CEUS may provide valuable information for plaque risk stratification and may play a role in the indication to treatment of patients with carotid stenoses, particularly in asymptomatic population.