99mTc-Annexin A5 for noninvasive characterization of atherosclerotic lesions: Imaging and histological studies in myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits

Seigo Ishino, Yuji Kuge, Nozomi Takai, Nagara Tamaki, H. William Strauss, Francis G. Blankenberg, Masashi Shiomi, Hideo Saji

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Purpose: Apoptosis is commonly observed in advanced atherosclerotic lesions. 99mTc-annexin A5 (99mTc-annexin V) has been proposed as a potential tracer for imaging apoptosis in atherosclerotic plaques. Accordingly, we determined the usefulness of 99mTc-annexin A5 as an atherosclerosis imaging tracer in a rabbit model (myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits; WHHLMI rabbits) of spontaneous atherosclerosis. Methods: The WHHLMI and control rabbits were injected intravenously with 99mTc-annexin A5. After in vivo planar imaging, the radioactivity in the aorta was measured. Autoradiography, TUNEL staining, Azan-Mallory staining and immunohistological studies were performed serially throughout the aorta. Results: 99mTc-Annexin A5 accumulation in the aorta of the WHHLMI rabbits was 5.6-fold higher than in that of control rabbits. Autoradiography showed heterogeneous multifocal accumulation of 99mTc-annexin A5 in WHHLMI rabbits. 99mTc-Annexin A5 accumulation was highest in the atheromatous lesions (6.2 ± 2.5, %ID × BW/mm2 × 103), followed in decreasing order by neointimal (4.9 ± 1.3), fibroatheromatous (4.5 ± 1.9), and collagen-rich lesions (3.3 ± 1.4). The regional 99mTc-annexin A5 accumulation was significantly correlated with the TUNEL-positive cell density, macrophage density and "vulnerability index," an index of the morphological destabilized characteristics. The in vivo imaging clearly visualized the atherosclerotic lesions in WHHLMI rabbits. Conclusion: The present study in WHHLMI rabbits showed higher 99mTc-annexin A5 accumulation in grade IV atheroma than in other more stable lesions. 99mTc-Annexin A5 may be useful in identifying atheroma that is at higher risk for rupture and possibly in assessing the response to anti-atherosclerotic therapy.

Original languageEnglish
Pages (from-to)889-899
Number of pages11
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume34
Issue number6
DOIs
StatePublished - Jun 2007
Externally publishedYes

Keywords

  • Annexin V
  • Apoptosis imaging
  • Atherosclerosis
  • Plaque
  • Radiolabeled proteins

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