2018 Fiscal Year Final Research Report

Useful Imaging to detect Macrophage Localization in the Media and Adventitia of the Abdominal Aortic Aneurysm Wall using Ex Vivo Superparamagnetic Iron Oxide-Enhanced Magnetic Resonance Imaging

Research Project

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Project/Area Number	15K10232
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Cardiovascular surgery
Research Institution	Tohoku University
Principal Investigator	Shimizu Takuya 東北大学, 医学系研究科, 大学院非常勤講師 (70579755)
Co-Investigator(Kenkyū-buntansha)	後藤均東北大学, 医学系研究科, 准教授 (00400333) 大田英揮東北大学, 医学系研究科, 准教授 (40586905) 中村保宏東北大学, 医学系研究科, 大学院非常勤講師 (80396499)
Research Collaborator	UMETSU Michihisa
Project Period (FY)	2015-04-01 – 2019-03-31
Keywords	SPIO MRI / 腹部大動脈瘤 / マクロファージの局在診断
Outline of Final Research Achievements	Macrophages in the aneurysmal wall play an important role in the pathogenesis of abdominal aortic aneurysms (AAAs). superparamagnetic iron oxide (SPIO) is a macrophage-specific contrast agent that result in negative enhancement on T2-weighted imaging. We attempted to evaluate macrophage localization in the media and adventitia of AAA wall using SPIO-enhanced MRI. Ex vivo MRI was performed for the specimens in SPIO group. There was significant positive correlation between berlin blue-stained macrophages and berlin blue positive area in SPIO group with macrophages. We divided the media and adventitia in each specimen and compared the ROI of T2-weighted SPIO-enhanced MRI with berlin blue-stained area. We found significant correlations in 5 of 7 cases with macrophages. We detected that ex vivo T2*-weighted SPIO-enhanced MR findings visualize a macrophage localization in the media and adventitia. This imaging technique would also visualize the macrophage distribution in in-vivo MRI.
Free Research Field	血管外科
Academic Significance and Societal Importance of the Research Achievements	腹部大動脈瘤が拡大する要因はいくつか報告されているものの、十分には解明されていない。瘤壁内のマクロファージが瘤形成に強く関わっているという組織学的な報告があるが、組織を取らずとも、瘤壁内のマクロファージの局在を示す方法＝可視化ができれば、将来大きくなりやすい瘤なのか、破裂しやすい瘤なのか、新たな指標に繋がる可能性がある。その第一段階として、採取した瘤壁のMRIと組織標本のマクロファージの局在に相関関係があることを明らかにした。今後生体内へ応用することで、新たな指標に繋がる可能性がある。