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.\r\nMaterials and methods: Fifty consecutive patients,either symptomatic and asymptomatic referring to\r\nour department in order to perform carotid endarterectomy(TEA),were enrolled.Each patient provided\r\ninformed consent before undergoing CEUS.Ultrasound examination was performed using high-frequency\r\n(8–14 MHz)linear probe and a non-linear pulse inversion technique(mechanicalindex:0.09–1.3).A\r\ndouble contrast media injection(Sonovue,2mLand4mL;Bracco,Italy)was performed.Two video-\r\ntapes were recorded for every injection:early “dynamic” phase and late “flash” phase,performed with\r\n6 high mechanical index impulses.Movies were quantitatively and qualitatively evaluated.Qualitative\r\nand quantitative evaluation were statistically compared to immunohistological diagnosis of vulnerable\r\nplaque, considered as gold standard.\r\nResults: Qualitative CEUS evaluation obtained high statistical results when compared to immunohisto-\r\nlogical results,with values of sensitivity,specificity,positive predictive value(PPV),negative predictive\r\nvalue (NPV),and diagnostic accuracy of 94%,68%,87%,85% and 86%,respectively,which became higher if\r\nconsidering only asymptomatic patient,with a NPV of 91%.Nevertheless, quantitative software evaluation\r\nproved less effective and could not reach similar results.\r\nConclusion: Carotid plaque enhancement assessed with CEUS well correlates with histological assessment\r\nof plaque instability.CEUS may provide valuable information for plaque risk stratification and may play\r\na role in the indication to treatment of patients with carotid stenoses, particularly in asymptomatic\r\npopulation.