Quantification of temporal changes in calcium score in active atherosclerotic plaque in major vessels by 18 F-sodium fluoride PET/CT

Abstract

Purpose

Our aim was to assess whether ¹⁸F-NaF PET/CT is able to predict progression of the CT calcium score.

Methods

Between August 2007 and November 2015, 34 patients (18 women, 16 men; age, mean ± standard deviation, 57.5 ± 13.9 years; age range 19–78 years) with malignancy or orthopaedic disease were enrolled in this study, with approximately 1-year follow-up data. Baseline and follow-up CT images were retrospectively evaluated for the presence of calcification sites in major vessel walls. The maximum and mean CT values (CTmax and CTmean, in Hounsfield units), calcification volumetric score (CVS, in cubic millimetres) and Agatston units score (AU) were evaluated for each site. Subsequent changes in CTmax, CTmean, CVS and AU were calculated and expressed as ΔCTmax, ΔCTmean, ΔCVS and ΔAU, respectively. We then evaluated the relationship between ¹⁸F-NaF uptake (using the maximum target-to-background ratio, TBRmax, and the maximum blood-subtracted ¹⁸F-NaF activity, bsNaFmax, which was obtained by subtracting the SUVmax of each calcified plaque lesion and NaF-avid site from the SUVmean in the right atrium blood pool) and the change in calcified plaque volume and characteristics obtained after 1 year.

Results

We detected and analysed 182 calcified plaque sites and 96 hot spots on major vessel walls. ¹⁸F-NaF uptake showed very weak correlations with CTmax, CTmean, CVS, CVS after 1 year, AU and AU after 1 year on both baseline and follow-up PET/CT scans for each site. ¹⁸F-NaF uptake showed no correlation with ΔCTmax or ΔCTmean. However, there was a significant correlation between the intensity of ¹⁸F-NaF uptake and ΔCVS and ΔAU.

Conclusion

¹⁸F-NaF uptake has a strong correlation with calcium score progression which was a predictor of future cardiovascular disease risk. PET/CT using ¹⁸F-NaF may be able to predict calcium score progression which is known to be the major characteristic of atherosclerosis.

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