Abstract 19281: CT Molecular Imaging of Perivascular Adipose Tissue and Its Linkage to Vascular Disease
Perivascular adipose tissue (PVAT) surrounds the major arteries and regulates endothelial functioning. Healthy PVAT has the brown adipose tissue (BAT) phenotype histologically, and possesses anti-inflammation and vasorelaxant characteristics, which are not observed in obesity. The hypothesis of this study is that molecular imaging using micro-computed tomography (microCT) combined with an iodinated fatty acid can detect healthy murine PVAT in rest and identify dynamic changes of PVAT after pharmacological or physiological interventions.
Methods: To investigate the in vivo kinetics of our iodinated fatty acid, C57BL/6J mice (n=6) were injected with this novel x-ray contrast agent, and serial microCT scans were performed at room temperature. It is well known that classical BAT can be regulated by temperature. In order to confirm that PVAT has the BAT phenotype, another eight mice were housed at room temperature and subsequently exposed to different temperatures (4 hours at 4°C or 30°C). They were then injected with the same contrast agent and imaged for PVAT using microCT. Additionally, we compared PVAT activity in 6 LDLR KO mice fed with a high-fat diet to activity in 6 LDLR KO mice fed with normal chow for 4 weeks, since mice fed with a long-term high-fat diet often have impaired endothelial functioning. In order to treat any potential decreases in PVAT activity, the same mice were given metformin with gavage for one week. PVAT was then imaged and quantified for activity and volume.
Results: In vivo microCT imaging discovered that the peak of iodinated fatty acid within PVAT was 4 hours after venous administration. Additionally, microCT showed that PVAT had the BAT phenotype at room temperature, which could be activated under acute cold exposure and inactivated in thermoneutral conditions. A high fat diet significantly diminished PVAT activity and active volume compared to a normal diet in LDLR KO mice. This reduced activity could be rescued with an anti-diabetic drug, because of its vascular protection potential to activate PVAT.
Conclusion: We successfully developed a molecular imaging approach that could detect healthy PVAT in mice and identify dynamic change of PVAT after physiological or pharmacological interventions.
Author Disclosures: Z.W. Zhuang: None. Y. Huang: None. X. Yang: None. K.A. Martin: None. J. Hwa: None. M. Simons: None.
- © 2016 by American Heart Association, Inc.