Published in:
01-06-2010 | Original Article
In vivo molecular imaging of myocardial angiogenesis using the αvβ3 integrin-targeted tracer 99mTc-RAFT-RGD
Published in: Journal of Nuclear Cardiology | Issue 3/2010
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Background
Myocardial angiogenesis following reperfusion of an infarcted area may impact on patient prognosis and pro-angiogenic treatments are currently evaluated. The non-invasive imaging of angiogenesis would therefore be of potential clinical relevance in these settings. 99mTc-RAFT-RGD is a novel 99mTc-labeled tracer that targets the αvβ3 integrin. Our objective was to determine whether this tracer was suitable for myocardial angiogenesis imaging.
Methods and Results
A rat model of reperfused myocardial infarction was employed. Fourteen days following reperfusion, the animals were injected with 99mTc-RAFT-RGD or with its negative control 99mTc-RAFT-RAD. Fourteen animals were dedicated to autoradiographic imaging, infarct staining, and gamma-well counting of myocardial activity. In vivo dual-isotope pinhole SPECT imaging of 201Tl and 99mTc-RAFT-RGD or 99mTc-RAFT-RAD was also performed in 11 additional animals. Neovessels were observed by immunostaining in the infarcted and peri-infarct areas. 99mTc-RAFT-RGD infarct-to-normal ratios by gamma-well counting and ex vivo imaging (2.5 ± 0.6 and 4.9 ± 0.9, respectively) were significantly higher than those of 99mTc-RAFT-RAD (1.7 ± 0.2 and 2.2 ± 0.4, respectively, P < .05). The infarcted area was readily visible in vivo by SPECT with 99mTc-RAFT-RGD but not with 99mTc-RAFT-RAD (infarct-to-normal zone activity ratio, 2.5 ± 0.6 and 1.7 ± 0.4, respectively, P < .05).
Conclusion
99mTc-RAFT-RGD allowed the experimental in vivo molecular imaging of myocardial angiogenesis.