Abstract 15323: Comparison of in vitro F-NaF Binding to Recovered Human Carotid Plaques After F-NaF in vivo Clinical Imaging
Background: Vascular calcification is a cell-mediated, pathological process in which calcium accumulates in blood vessels. Microcalcification (<50 μm) is associated with high-risk and ruptured plaques, thus timely identification would help patient stratification and development of new pharmacotherapies. 18F-NaF PET/CT recently has emerged as a potential marker for microcalcifications, yet its specificity and sensitivity are not well characterized.
Methods: Patients were imaged with 18F-NaF PET/CT prior to endarterectomy, carotids were recovered with IRB approval. Specimens were incubated in 10-9 M 18F-NaF and imaged with μPET/μCT. They were re-incubated in 18F-NaF, sectioned and autoradiographed. Finally, calcium was detected histologically.
Results: Clinical CT detected macrocalcifications (>50 μm), while PET detected both macrocalcifications and areas with no apparent calcification. μCT matched the clinical CT signal but also detected smaller macrocalcifications and finer structure. μPET refined signal and showed both macro- and microcalcifications (Fig. 1). Histology enhanced the interpretation of CT signal revealing microcalcifications and autoradiography showed better spatial resolution for otherwise similar signal as μPET.
Further analysis of all modalities revealed that 18F-NaF could only bind to the surface level of macrocalcifications, while microcalcifications had no barriers to penetration. If macrocalcifications were sectioned and then exposed to 18F-NaF, the ligand bound across the whole macrocalcification surface.
Conclusion: 18F-NaF signal is dependent on the surface area of calcifications, as it bound only to the top layer of the calcifications without penetrating into deeper levels. These findings were replicated on three levels [[Unable to Display Character: –]] microscopic/autoradiography, μPET/μCT and also in vivo in the clinical PET/CT. These characteristics position 18F-NaF as a specific ligand for active microcalcification detection.
Author Disclosures: A. Irkle: None. A.T. Vesey: None. D.Y. Lewis: None. J.N. Skepper: None. J.L. Bird: None. M.R. Dweck: None. F.R. Joshi: None. F.A. Gallagher: None. E.A. Warburton: None. M.R. Bennett: None. K. Brindle: None. D.E. Newby: None. J.H. Rudd: None. A.P. Davenport: None.
- © 2014 by American Heart Association, Inc.