Evaluation Of Carotid Artery Plaque Stability By Contrast-enhanced Ultrasonography Combined With¹⁸F-FDG PET/CT

Objective: To evaluate the stability of carotid plaque by assessment ofneovascularization in the plaque with contrast-enhanced ultrasonography (CEUS) anddetection of macrophage with positron emission tomography-computed tomography(PET/CT).Method: Forty-seven patients with52carotid artery plaques received examinationswith CEUS. According to the ultrasonic nature of the plaques,the patients were dividedinto soft and mixed plaque group(n=24) and hard and calcified plaque group(n=26). Theplaque maximal intensity (IMAX),rise time,time to peak,mean transition time andplaque maximal density (DMAX) of the plaques were measured to quantify theneovasculature. Then we divided these plaques into three groups according to MRIfindings.Characteristics of these plaques determined by two-dimensional ultrasono-graphy and CEUS were compared between these groups.The patients also underwentconcurrent18F-FDG PET/CT, and18F-FDG uptake was quantified by the mean standarduptake values (SUVmean) and target-background ratio(TBR),two indexes reflecting theinflammatory activity in the plaque. The overall and subgroup findings in CEUS andPET/CT were comparatively analyzed for these cases.Results: The DMAX of the plaque in soft and mixed plaque group was significantlyhigher than that in hard and calcified plaque group (4.78±5.12vs2.31±2.56, P<0.05);The volume of lipid-rich necrotic core(LRNC) was higher in soft plaque group thanhard plaque,mixed plaque and calcified plaque(P<0.05). The volume of intraplaguehemorrhage(IPH) was higher in soft plaque group than hard plaque,mixedplaque(P<0.05). IMAX and DMAX were not found to correlate with SUV mean andTBR(P<0.05).TBR and DMAX have moderate correlation in the soft and mixedplaques(P<0.05).TBR and DMAX have moderate correlation in phase IV~V plaquesdetermined by MRI (P<0.05). Conclusion: CEUS can sensitively show the status of neovascularization within thecarotid atherosclerosis plaques, and PET/CT findings reflects the inflammatory activityin these plaques. Different types of plaques can be distinguished by the DMAX. Thereis a certain correlation between the values of TBR and DMAX in phase IV~V plaqueand in soft and mixed plaque.