Figure 1

¹⁸F-Fluoride binding in ex vivo coronary artery specimens. (A) Total activity of ¹⁸F-fluoride (MBq/mL) following 20 min incubation in hydroxyapatite plotted against dose of ¹⁸F-fluoride (kBq) per milligram of hydroxyapatite. Scatchard plot of bound/free versus bound ¹⁸F-fluoride (inset). (B) Hydroxyapatite and other calcium-derived minerals were incubated with ¹⁸F-fluoride for 20 min after which unbound supernatant was removed and the solid particles were analysed by micro positron emission tomography. Data shown is from at least three replicates and shown as the mean ± standard deviation. (C) Micro-computed tomography defined regions of myocardium (CT number < 100) from coronary plaque (CT number > 300). Calcification had high CT attenuation on micro-computed tomography (CT number > 1000). Quantitative ¹⁸F-fluoride positron tomography was analysed on hybrid images. (D) Non-specific binding in the surrounding myocardium was higher than background activity (median 14.9 [interquartile range 9.6–27.4] versus 0.30 [interquartile range, 0.09–1.3] kBq/mL respectively, p < 0.0001). Signal in coronary artery segments was tenfold higher (p < 0.0001) than myocardium (non-calcified plaque median 158.1 [interquartile range, 121.7–234.8] kBq/mL and calcified plaque median 149.8 [interquartile range, 85.3–207.3] kBq/mL). CaPi calcium bisphosphate, CaPyr calcium pyrophosphate, CaOx calcium oxalate, HAP hydroxyapatite, WL window level, WW window width. *Indicates p < 0.0001