Coronary arterial 18F-sodium fluoride uptake: a novel marker of plaque biology.
Dweck MR., Chow MWL., Joshi NV., Williams MC., Jones C., Fletcher AM., Richardson H., White A., McKillop G., van Beek EJR., Boon NA., Rudd JHF., Newby DE.
OBJECTIVES: With combined positron emission tomography and computed tomography (CT), we investigated coronary arterial uptake of 18F-sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG) as markers of active plaque calcification and inflammation, respectively. BACKGROUND: The noninvasive assessment of coronary artery plaque biology would be a major advance particularly in the identification of vulnerable plaques, which are associated with specific pathological characteristics, including micro-calcification and inflammation. METHODS: We prospectively recruited 119 volunteers (72 ± 8 years of age, 68% men) with and without aortic valve disease and measured their coronary calcium score and 18F-NaF and 18F-FDG uptake. Patients with a calcium score of 0 were used as control subjects and compared with those with calcific atherosclerosis (calcium score >0). RESULTS: Inter-observer repeatability of coronary 18F-NaF uptake measurements (maximum tissue/background ratio) was excellent (intra-class coefficient 0.99). Activity was higher in patients with coronary atherosclerosis (n = 106) versus control subjects (1.64 ± 0.49 vs. 1.23 ± 0.24; p = 0.003) and correlated with the calcium score (r = 0.652, p < 0.001), although 40% of those with scores >1,000 displayed normal uptake. Patients with increased coronary 18F-NaF activity (n = 40) had higher rates of prior cardiovascular events (p = 0.016) and angina (p = 0.023) and higher Framingham risk scores (p = 0.011). Quantification of coronary 18F-FDG uptake was hampered by myocardial activity and was not increased in patients with atherosclerosis versus control subjects (p = 0.498). CONCLUSIONS: 18F-NaF is a promising new approach for the assessment of coronary artery plaque biology. Prospective studies with clinical outcomes are now needed to assess whether coronary 18F-NaF uptake represents a novel marker of plaque vulnerability, recent plaque rupture, and future cardiovascular risk. (An Observational PET/CT Study Examining the Role of Active Valvular Calcification and Inflammation in Patients With Aortic Stenosis; NCT01358513).