Relation of carotid artery 18F-FDG uptake to C-reactive protein and Framingham risk score in a large cohort of asymptomatic adults

We investigated the relation of carotid (18)F-FDG uptake to high-sensitivity C-reactive protein (hsCRP) and Framingham risk score (FRS) in a large cohort of asymptomatic adults.

Methods: Carotid artery (18)F-FDG uptake was measured on the PET/CT scans of 1,181 asymptomatic subjects, and maximum target-to-background ratio (M-TBR) and intima-media thickness (IMT) were compared with clinical risk factors and hsCRP. The estimated 10-y risk for general cardiovascular disease was calculated by FRS.

Results: FRS increased from 11.5% ± 7.8% to 14.8% ± 10.5% in subjects with an M-TBR ≥ 1.7, compared with < 1.7, and the odds ratio for an FRS ≥ 10% was 1.9 (95% confidence interval [CI], 1.4-2.5). Adjusting for age confirmed a significant association of M-TBR and IMT with FRS. Independent determinants of high M-TBR were abdominal fat (β coefficient [B], 1.1040; P < 0.0001), low-density lipoprotein (LDL) (B, 0.0006; P < 0.05), and FRS (B, 0.0025; P < 0.05) for subjects < 50 y and abdominal fat (B, 0.9740; P < 0.0001), age (B, 0.0040; P = 0.0001), LDL (B, 0.0008; P = 0.0001), and IMT (B, 0.1097; P < 0.01) for subjects ≥ 50 y. Although hsCRP also stratified subjects for FRS-based risk, no correlation was found between hsCRP and M-TBR or IMT, suggesting that they may have different inferences. Importantly, in the low-hsCRP (14.2% ± 9.7% vs. 11.3% ± 7.4%) and high-hsCRP groups (18.8% ± 14.3% vs. 13.3% ± 10.2%), FRS was significantly greater for subjects with high M-TBR than for those with low M-TBR. The odds ratio for FRS ≥ 10% between subjects with high and low M-TBR was 1.20 (95% CI, 0.90-1.60; P = 0.209) in the low-hsCRP group and 2.95 (95% CI, 1.48-5.86; P = 0.002) in the high-hsCRP group.

Conclusion: High carotid (18)F-FDG uptake in asymptomatic adults is associated with increased clinical risk factors and FRS. Furthermore, it appears to reflect aspects of atherosclerotic inflammation distinct from hsCRP concentration and may offer incremental information regarding cardiovascular risk.