瀬尾 由広¹, 石津 智子¹, 鶴田 和太郎², 田口 夏美³, 鈴木 謙介⁴, 松村 明², 青沼 和隆¹

Yoshihiro SEO¹, Tomoko ISHIZU¹, Wataro TSURUTA², Natsumi TAGUCHI³, Kensuke SUZUKI⁴, Akira MATSUMURA², Kazutaka AONUMA¹

¹筑波大学大学院人間総合科学研究科循環器内科, ²筑波大学大学院脳神経外科, ³筑波大学附属病院検査部, ⁴獨協医科大学越谷病院脳神経外科

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

キーワード : B-flow imaging, carotid plaque, neovascularization

目的：プラーク内血管新生はプラーク内出血を生じプラークを不安定化させる一因である．我々はB-flow imagingが微小な血流を描出が可能なことから，本法による頸動脈プラーク内新生血管の描出を試みた．対象と方法：虚血性脳血管障害により頸動脈内膜剥離術を行われた7例（全例男性，平均年齢68.6±4.8歳）．超音波診断装置はGE社製Vivid 7，超音波探触子は9‐14 MHzリニアアレイ探触子を使用した．術前に頸動脈プラークの観察を行い，プラーク輝度をgray-scale medium（GSM）で定量化した．B-flow imagingでプラーク領域を多断面で注意深く観察し，プラーク内における血流と考えられるB-flow信号の有無を検索した．結果：7例中6例においてプラーク内に血流信号を認めた．これら6例のGSMは平均32±10と超音波輝度が低値であった．3例では複数のプラーク内血流信号が観察され，プラークは脂質コア成分が多く，プラーク内には微小血管が複数存在していた．また，2例ではプラーク外膜側に血流像が偏在しており，病理所見では壊死組織に加えてプラーク内出血が顕著であった．プラーク内に血流信号が明らかでなかった1例は，GSMが66を示し，線維化や石灰化が他の症例に比較して顕著で，プラーク内微小血管は明らかでなかった．結論：B-flow imagingによりプラーク内新生血管の描出が可能であり，組織性状の診断に有用である可能性が示唆された．

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.