The Study Of In Vivo Internal Carotid Artery Atherosclerotic Plaque Vulnerability By Contrast-enhanced Ultrasound Imaging

Internal carotid artery (ICA) atherosclerosis is an important pathologicalbasis of the ischemic cerebrovascular disease. Unstable carotid plaque ruptureand thrombosis embolism is the important reason for the occurrence ofcerebrovascular events and death, so the accurate identification of the plaquesvulnerability to prevent the occurrence of cerebral infarction is extremelysignificant. Studies have suggested that plaque neovascularization can inducethe hemorrhage and rupture and be associated with plaque vulnerabilityclosely.There has been a growing body of interest in the assessment of plaqueneovascularization.Contrast-enhanced ultrasound (CEUS) technology canidentify plaque neovascularization by enhancing echo contrast between theblood flow and the tissue, and is used to evaluate the vulnerability of the plaques.In this study we analysised the degree of the plaque neovascularization useingCEUS technology combined with microembolic signals (MESs) monitoringtechnology and magnetic resonance imaging(MRI),to characterize thevulnerable ICA atherosclerotic plaques,and to prove the CEUS technique is apotentially promising noninvasive tool that can be used in stratifying strokerisk in patients with ICA atherosclerotic disease.Part one The study of the correlation between ICA plaque vulnerabilityand plaque neovascularizationObjective: The aim of this study was to compare the plaqueneovascularization properties between symptoms and asymptomatic ICAatherosclerotic stenosis using CEUS technique. Methods:CEUS were acquiredin33patients with symptomatic and13patients with asymptomatic ICA atherosclerotic stenosis (≥50%).,Contrast microbubbles detected within theplaque indicated neovascularisation and were quantified by decibel enhancement(dB-E) using the ACQ analysis software in the machine, the results of ICAplaques on CEUS were compared between the two groups. Results: In46patients, dB-E was significantly greater in symptomatic (22.76±1.95) vs.asymptomatic (14.99±2.18) patients (P<0.01). In the same group the arrival time(AT) and the time to peak intensity(TPI) have significantly difference indifferent position (P<0.01), and did not have significantly difference in the sameposition of different group (P>0.05).Conclusion: Different density ofintraplaque nevascularization in carotid arteries were observed betweensymptomatic and asymptomatic ICA stenosis. The real-time CEUS can observethe neovascularization within carotid atherosclerotic plaque non-invasively andquantitatively and can be used to assess the plaque vulnerability.Part Two An assessment of the vulnerability of carotid plaques: acomparative study of intraplaque neovascularization and plaqueechogenicityObjective: The aim of this study was to compare CEUS and CDUS in theassessment of plaque vulnerability using transcranial color Doppler (TCD)monitoring of microembolic signals (MES) as a reference technique. Methods: Atotal of46subjects with arterial stenosis (≥50%) underwent a carotid duplexultrasound, TCD monitoring of MES and CEUS (SonoVue doses of2.0mL)within a span of3days. The agreement between the CEUS, CDUS, and MESfindings was assessed with a chi-square test. A p-value less than0.05wasconsidered statistically significant.Results: Neovascularization was observed in30lesions (65.2%). The vascular risk factors for stroke were similar and therewere no age or gender differences between the2groups. Using CEUS, MES wereidentified in2patients (12.5%) within class1(non-neovascularization) as opposed to15patients (50.0%) within class2(neovascularization)(P=0.023).CDUS revealed no significant differences in the appearance of the MES betweenthe2groups (hyperechoic and hypoechoic)(P=0.237). Conclusion: MESs wereobserved more frequently in the neovascularization group detected by CEUS.CEUS may be better in identifying plaque vulnerability than CDUS.Part three The study of plaque neovascularization by contrast-enhancedultrasound: Correlation with the ipsilateral infarctsObjective: The aim of this study was to compare the correlation betweenthe plaque neovascularization properties and ipsilateral infarcts of the ICAatherosclerotic stenosis using MRI.Methods: A total of32patients withICA stenosis (≥50%)underwent CEUS and MRI.The results of ICAplaques on CEUS and the MRI were compared. Results: The ipsilateral lesionsof the ICA atherosclerotic stenosis at MRI were correlated with higher dB-E(23.31±1.83vs.16.62±3.07, P<0.01) plaques. Conclusion: The plaqueneovascularization degree showed a high correlation with the ipsilateral brainischemia event.Part four The study of the diagnostic concordance between colourDoppler ultrasonography and contrast-enhanced ultrasound in assessingcarotid artery near-occlusion(NO)Objective: The aim of this study was to evaluate the diagnostic concordancebetween colour Doppler ultrasonography and contrast-enhanced ultrasound inassessing carotid artery occlusion and NO.Methods: A total of53consecutivepatients with internal carotid artery (ICA) disease，who were diagnosed severestenosis（≥70%）by CDUS（Combining the linear array and the convexarray）,all the53patients were performed CEUS. The results of CEUS andCDUS were compared.Results: In53patients,55vessels were investigated byCDUS, all these vessels were underwent by CEUS for analysis. In these vessels 43of55(78.2%)were diagnosed severe stenosis,7of55(12.7%)were diagnosedocclusion and5of55(9.1%) NO by CDUS.All the Results agree with CEUS.NOvessels diagnosed occlusion by CDUS while diagnosed NO byCEUS.Conclusion: CDUS and CEUS indicateD a high concordance in theappreciation of carotid artery occlusion or subtotal occlusions.