Abstract 498: In vivo Assessment of Murine Valvular and Vascular Calcification Using 18 F Sodium Fluoride Micro Positron-Emission Tomography and Computed Tomography

Calcific aortic valvular and vascular disease (CAVVD) is associated with increased morbidity and mortality. In addition to the commonly practiced computed tomography (CT) to evaluate for the presence of CAVVD, recent work has demonstrated the use of 18 F-sodium fluoride positron-emission tomography ( 18 F-PET) to assess both valvular and vascular calcification in humans. In this pilot study, we combined 18 F μPET and μCT to assess for aortic valvular and aortic arch calcification in vivo . Aged Apoe -/- mice (n=5) were injected with ~200 μCi 18 F-sodium fluoride and, one hour later, were imaged with fused μPET-μCT (Figure A,C). Intravenous contrast was used for the μCT studies to assist with anatomic localization (Figure B,D). To assess valvular hemodynamics, direct cardiac catheterization was performed on the mice to determine the peak-to-peak pressure gradient (PPG) across the aortic valve, between the left ventricle and aorta (Figure E,F). All mice were found to have aortic arch calcification present on both μPET and μCT imaging. In mice with aortic valve calcification specifically identified on μPET-μCT (Figure A-D, red arrows), there was increased 18 F uptake in the heart and aorta (58.8 ± 7.7 %ID/cc) compared to the mouse without aortic valve calcification (16.2 %ID/cc). Additionally, in the mice with aortic valve calcification, the mean transvalvular PPG was 9.7 ± 2.5 mmHg, and in the mouse without valvular calcification, the PPG was 3.3 mmHg. Alizarin red staining of histological sections from the aortic valves and aortic roots from these mice was performed to assess for the presence of calcium mineral. In conclusion, these findings suggest that the use of 18 F μPET-μCT in small animals provides a method to determine the presence of CAVVD in vivo . Future studies will determine whether changes in 18 F μPET-μCT signal reliably correlate with meaningful changes in CAVVD.