| BACKGROUND-.Besides the degree of stenosis,the stability of carotid plaque is also important in development of clinical events .Plaque contents and structure may play an important role in plaque instability,so using noninvasive ultrasound and MRI to assess the contents of atherosclarotic plaques at the carotid bifurcation has great value.these imaging techniques could be important in evaluating the progression of carotid artery atherosclerosis and its response to pharmacologic and surgical intervention.The stability of plaque is related to its cellular components too.As the major cellular component of connective tissue,mast cells have the potential to influence the extracellular matrix component of plaque through the production of potent mediators such as proteases and a broad spectrum of multifunctional cytokines.The present of increased numbers of mast cells in coronary plaque has been reported,but there was no any experimental report about the quantity and distribution of mast cell in carotid plaque .PURPOSE:(1) To correlate ultrasound and MRI imaging of atherosclerotic plaque at the carotid bifurcation with histologic analysis,and perform densitometric analysis of ultrasound images of carotid plaques.(2)To study quantity and distribution of two different phenotype mast cell in atherosclerotic lesions of human carotid arteries,and to evaluate the influence of mast cell on stability of carotid plaque.METHODS:(1)20 patients(22 lesions) scheduled for carotid endarterectomy were examined by high resolution B-mode ultrasound and high resolution MRI preoperatively,the images of carotid plaque was recorded. The postoperative specimens were also examined by high resolution B-mode ultrasound and high resolution MRI.The transverse pathological sections of plaques were made and were matched with images of ultrasound and MRI,using carotid bifurcation,calcification and the shape of plaque and lumen as the landmark.Performing 256 gray scale ultrasound densitometric analysis of carotid plaque compositions and correlating MRI images of atherosclerotic plaque with histologic findings such as calcium,fibrous tissue,old hemorrage/thrombus and lipid deposits.(2)32 samples of endarterectomy and 10 autopsy normal carotid specimens were fixed and embeded in paraffin,serial sections were stained with hematoxylin-eosin,Toluidine blue stains,monoclonal antibodies against the two major proteases of mast cell(tryptase and chymase) and monoclonal antibodies against CD-3 of T lymphocyte and CD-68 of macrophage. The quantity,distribution and degranule of two different phenotype mast cell in atherosclerotic lesions of human carotid arteries was investigated,and the ratio of mast cell to T lymphocyte and macrophage in atherosclerotic lesions was calculated.RESULTS:(l)Ultrasonic density measurement of calcium,fibrous tissue,hemorrage/thrombus and lipid deposits was 89 +12, 53 + 8, 37 + 6 and 39 + 3 respectively in vivo. Ultrasonic density measurement of calcium,fibrous tissue,hemorrage/thrombus and lipid deposits was 168?1, 136 + 12, 85 + 12 and 89 + 10 respectively in vitro.There were significant statistics difference of density measurement between different components except between hemorrage/thrombus and lipid deposits.In vivo relative signal intensities of calcium,fibrous tissue,old hemorrage/thrombus and lipid deposits were low,equal,equal and very high respectively on T1W MR image(relative to signal intensity of muscle). In vivo relative signal intensities of calcmm,fibrous tissue,old hemorrage/thrombus and lipid deposits were very low,equal,high and high respectively on PDW MR image. In vivo relative signal intensities of calcium,fibrous tissue,old hemorrage/thrombus and lipid deposits were low,equal or slight high,high and high respectively on T2W MR image. Signal intensities of plaque contents in vivo were corelated to signal intensities ex vivo.Calcium and thick fibrous cap were identified very well on T1W and PDW images, hemorrage/thrombus and lipid deposits also could be identified,but it was diffi...
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