1Cardiovascular Division, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 2Department of Neurosurgery, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 3Clinical Laboratory, Tsukuba University Hospital, 4Department of Neurosurgery, Dokkyo University School of Medicine, Koshigaya Hospital
Purpose: To elucidate the critical role of intraplaque neovascularization of microvessel-derived intraplaque hemorrhage in the development of acute lesion instability. We designed this study to visualize carotid plaque neovascularization using B-flow imaging, which can visualize microvascular flow. Subjects and Methods: Seven patients (7 men, 68.6±4.8 yrs) who had been referred for carotid endarterectomy were enrolled.Carotid ultrasound examinations were carried out using a Vivid 7 system with a multifrequency linear array transducer. Measurement of carotid plaque echogenity was based on gray-scale median (GSM) value. Intraplaque microvascular flow signals were carefully assessed by B-flow imaging. Results and Discussion: Intraplaque flow signals were observed in six patients. Gray-scale median values of these plaques were low (32±10). Multiple flow signals were observed in three patients in whom histologic studies revealed enhanced neovascularization with a lipid-rich core. In two patients whose intraplaque flow signals were situated at the peri-adventia, histologic studies revealed massive intraplaque hemorrhage with a necrotic core. In one patient, plaque producing no flow signals showed greater fibrous change, more calcification, and less neovascularization. Conclusion: B-flow imaging visualized intraplaque flow signals and provided additional information on plaque characterization.