TY - JOUR
T1 - Detection of Macrophage Localization in the Abdominal Aortic Aneurysm Wall Using Ex Vivo Superparamagnetic Iron Oxide–Enhanced Magnetic Resonance Imaging
AU - Umetsu, Michihisa
AU - Goto, Hitoshi
AU - Nakamura, Yasuhiro
AU - Ota, Hideki
AU - Shimizu, Takuya
AU - Hashimoto, Munetaka
AU - Akamatsu, Daijirou
AU - Kamei, Takashi
N1 - Funding Information:
This study was registered in the University Hospital Medical Information Network (UMIN) Clinical Trials Registry, which meets the criteria of the International Committee of Medical Journal Editors (no. UMIN000022314). This study was supported by a Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (C) (no. 15K10232).
Publisher Copyright:
© 2020 Elsevier Inc.
PY - 2020/10
Y1 - 2020/10
N2 - Background: 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 results in negative enhancement on magnetic resonance imaging (MRI). SPIO-enhanced MRI targeting the intraluminal thrombus of AAAs has been previously reported. However, macrophages in the media and adventitia of AAA wall have not been investigated in detail. This study aimed to evaluate macrophage localization using SPIO-enhanced MRI in the media and adventitia of AAA wall, as macrophages play a crucial role in AAA pathogenesis. Methods: Here, we included study and control patients planning to undergo open surgery for AAA. The study patients received SPIO injection 2 days preoperatively (the SPIO group, n = 7), whereas the control patients did not receive this injection (the control group). Ex vivo MRI was performed on the harvested AAA wall in the SPIO group during the surgery. The concordance between the number of macrophages and berlin blue (BB)–stained areas was histologically evaluated in both groups. Moreover, the concordance between regions of interest in MR images and BB-stained areas was evaluated. Results: The proportion of BB-stained macrophages was higher in the SPIO group (0.93; interquartile range [IQR], 0.83–0.95) than in the control group (0.03; IQR, 0.026–0.11) (P < 0.05), indicating uptake of SPIO by macrophages in the AAA wall. A significant positive correlation was found between the number of BB-stained macrophages and BB-stained areas using Kendall rank correlation coefficient in the SPIO group (τ = 0.58; P < 0.05). Significant correlations were found in the distributions of the region of interest of SPIO-enhanced MRI and BB-stained areas in the media and adventitia in 5 of 7 patients. Conclusions: Macrophages present in the media and adventitia of the AAA wall showed an uptake of the SPIO contrast agent injected 2 days prior, which were then detected by ex vivo MRI. This suggests that SPIO-enhanced MR images help detect the localization of macrophages on the AAA wall, indicating its potential to serve as a novel index for AAA pathogenesis.
AB - Background: 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 results in negative enhancement on magnetic resonance imaging (MRI). SPIO-enhanced MRI targeting the intraluminal thrombus of AAAs has been previously reported. However, macrophages in the media and adventitia of AAA wall have not been investigated in detail. This study aimed to evaluate macrophage localization using SPIO-enhanced MRI in the media and adventitia of AAA wall, as macrophages play a crucial role in AAA pathogenesis. Methods: Here, we included study and control patients planning to undergo open surgery for AAA. The study patients received SPIO injection 2 days preoperatively (the SPIO group, n = 7), whereas the control patients did not receive this injection (the control group). Ex vivo MRI was performed on the harvested AAA wall in the SPIO group during the surgery. The concordance between the number of macrophages and berlin blue (BB)–stained areas was histologically evaluated in both groups. Moreover, the concordance between regions of interest in MR images and BB-stained areas was evaluated. Results: The proportion of BB-stained macrophages was higher in the SPIO group (0.93; interquartile range [IQR], 0.83–0.95) than in the control group (0.03; IQR, 0.026–0.11) (P < 0.05), indicating uptake of SPIO by macrophages in the AAA wall. A significant positive correlation was found between the number of BB-stained macrophages and BB-stained areas using Kendall rank correlation coefficient in the SPIO group (τ = 0.58; P < 0.05). Significant correlations were found in the distributions of the region of interest of SPIO-enhanced MRI and BB-stained areas in the media and adventitia in 5 of 7 patients. Conclusions: Macrophages present in the media and adventitia of the AAA wall showed an uptake of the SPIO contrast agent injected 2 days prior, which were then detected by ex vivo MRI. This suggests that SPIO-enhanced MR images help detect the localization of macrophages on the AAA wall, indicating its potential to serve as a novel index for AAA pathogenesis.
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U2 - 10.1016/j.avsg.2020.04.067
DO - 10.1016/j.avsg.2020.04.067
M3 - Article
C2 - 32439528
AN - SCOPUS:85086518758
SN - 0890-5096
VL - 68
SP - 344
EP - 350
JO - Annals of Vascular Surgery
JF - Annals of Vascular Surgery
ER -