172Coronary 18F-sodium fluoride uptake predicts progression of coronary arterial calcification

Abstract Background Combined positron emission tomography and computed tomography (PET-CT) using 18F-sodium fluoride (18F-NaF) to detect microcalcification provides the opportunity to gain important insights into disease activity in coronary atherosclerosis. However, the relationship between 18F-NaF uptake and progression of coronary calcification has not been determined. Purpose To determine the relationship between 18F-NaF uptake and progression of coronary calcification in patients with clinically stable coronary artery disease (CAD). Methods Patients with established, multivessel CAD underwent 18F-NaF PET-CT and CT coronary calcium scoring at baseline, with repeat CT calcium scoring at one year. Coronary arterial PET uptake was analysed qualitatively and semi-quantitatively in diseased vessels by measuring maximum tissue-to-background ratio (TBRmax) – defined as the maximum standardised uptake value in a plaque divided by mean blood pool activity measured in the right atrium. Coronary calcification was quantified by measuring calcium mass, volume, average calcium density and total Agatston score (AU). Results In total, 185 patients underwent baseline and repeat imaging (median age 66 years, 80% men), and 118 (64%) had increased 18F-NaF uptake in at least one vessel. Median total calcium score, volume, mass and average density were higher in patients with compared to those without increased 18F-NaF uptake (Table 1). At one year, patients with evidence of increased 18F-NaF uptake demonstrated more rapid progression of coronary calcification (97 [39–166] AU) versus those without uptake (35 [7–93] AU; p<0.0001). Amongst 18F-NaF-positive patients, the calcium score increased only in coronary segments with 18F-NaF uptake (baseline 90.5 [27.5–202] AU versus one year 135.5 [59.3–281.8] AU; p<0.0001) and not in 18F-NaF-negative segments (baseline 44.5 [16–110.5] AU versus one year 46.5 [18.25–114] AU; p=0.446). There was a moderate correlation between TBRmax and change in total calcium score, volume and mass at 1 year (Spearman's Rho = 0.37, 0.38, 0.46 respectively; p<0.0001 for all). Coronary calcification at baseline in PET-negative and PET-positive patients All patients (n=185) 18F-NaF Positive (n=118) 18F-NaF Negative (n=67) P value Agatston Score (AU) 381 [107–892] 541 [245–1130] 136 [55–361] p<0.0001 Calcium Volume (mm3) 358 [131–787] 506 [251–1014] 131 [64–343] p<0.0001 Calcium Mass (mg) 71 [23–155] 100 [48–222] 24 [11–69] p<0.0001 Average Density (mg/mm3) 0.19 [0.17–0.22] 0.20 [0.18–0.23] 0.18 [0.16–0.20] p<0.0001 Conclusions Coronary 18F-NaF uptake identifies both patients and individual coronary segments with greater disease and more rapid progression of coronary calcification over one year. Acknowledgement/Funding AstraZeneca (unrestricted educational grant). British Heart Foundation (CH/09/002, RE/13/3/30183, FS/17/79/33226) Wellcome Trust (WT103782AIA).