P5.15 EVALUATION OF AORTIC 18F-NAF TRACER UPTAKE DETECTED USING PET/CT IN PREDICTING AORTIC CALCIFICATION OVER A 4-YEAR FOLLOW-UP PERIOD

Abstract

Background: Uptake of 18F-sodium fluoride (18F-NaF) in the aortic wall may reflect metabolically active areas of calcification, an important predictor of cardiovascular morbidity and mortality when detected by computed tomography (CT). The aim of this project was to determine if 18F-NaF uptake in the aorta can predict development of calcification as detected by CT. Method and results: Twenty one postmenopausal women (mean age 62±6 years, range 52-74), underwent assessment of aortic 18F-NaF uptake using positron emission tomography/computer tomography (PET/CT) at baseline and after a mean follow-up of 3.7±1.3 years. Tracer uptake was quantified by calculating the target-to-background ratios (TBR). At baseline, there was a trend to a positive correlation between CT calcium volume score and tracer uptake (r=0.33, P=0.15). Over the follow-up period aortic CT calcium volume increased from 0.45±0.62 to 0.71±0.93 cm3 (P<0.04). However, the change in calcium volume did not significantly correlate with baseline TBR values (r=0.18, P=0.52). TBR at baseline did not differ between participants with (n=16) compared to those without (n=5) progression in calcium volume progression (2.43±0.46 vs. 2.31±0.38, P=0.58). In aortic segments identified to have highest tracer uptake at baseline, calcium volume did not significantly change over the follow-up period (from 0.08±0.15 to 0.12±0.26 cm3, P=0.42). In multivariate regression analysis baseline TBR did not associate with progression in calcium volume. Conclusion: In a cohort of postmenopausal women 18F-NaF uptake as measured by TBR was not a predictor of progression of aortic calcification as detected by CT over a 4-year follow-up period.