Enhanced Uptake of FDG in PET/CT After the Use of Bone Wax During Sternotomy

Physiologic healing processes and foreign body reactions can mimic infective conditions in ¹⁸F-FDG-PET/CT for the detection of deep sternal wound infections. To date, nothing is known about the metabolic presentation of surgically applied bone wax to the sternum for hemostasis during sternotomy in ¹⁸F-FDG-PET/CT imaging. Therefore, this study aims to assess the sternal FDG uptake after the application of bone wax during sternotomy.

A total of 25 patients with a history of cardiac surgery (1.3-5.5 years ago) were examined by ¹⁸F-FDG-PET/CT with dual time point imaging. The sternal FDG uptake was assessed visually (as positive or negative) and metrically using the maximum standardized uptake values (SUV_max) calculated automatically. The SUV_max was compared between the patients with and without the use of bone wax and among patients with and without positive sternal findings in the visual analysis. A correlation analysis was performed between the time since surgery and the sternal SUV_max.

In all eight patients (32%) had received bone wax. In those patients, the mean sternal SUV_max was higher compared to the group without bone wax, both in the early (4.74 ± 1.28 vs. 3.70 ± 1.44; p = 0.0969) and in the late images (6.62 ± 2.67 vs. 4.36 ± 1.44; p = 0.0289). Moreover, the use of bone wax was strongly associated with positive sternal findings in the visual analysis (OR = 10; 95%CI = 0.995-100.462; p = 0.0421). The correlation analysis revealed a slightly decreasing trend without significance (Spearman's ρ = -0.139; p = 0.505).

The use of bone wax during sternotomy could be associated with increased sternal uptake of FDG on ¹⁸F-FDG-PET/CT, even several years after surgery. This finding should be considered in the evaluation of potential deep sternal wound infections.