Prevention of Brown Adipose Tissue Activation in 18F-FDG PET/CT of Breast Cancer Patients Receiving Neoadjuvant Systemic Therapy

F-18-FDG uptake in brown adipose tissue (BAT) can complicate interpretation and quantification of PET images, especially in regions of possible lymph node metastases such as the axilla and the mediastinum. The aim of this study was to prospectively evaluate the effect of patient preparation using a single oral dose of diazepam and controlled indoor temperature to prevent F-18-FDG uptake in BAT in breast cancer patients referred for monitoring of therapy response with F-18-FDG PET. Methods: During the fall and winter months, 53 patients referred for F-18-FDG PET/CT of breast cancer were included. A cohort of 25 patients was imaged without an intervention, and a second cohort of 28 patients was prepared according to a new protocol that included 10 mg of diazepam and adequate indoor temperature. The generated images were visually assessed for the presence of F-18-FDG at the location of fat-density tissue on CT images using a 4-point scale. Results: In the cohort without intervention, relevant F-18-FDG uptake in BAT was identified in 4 patients (16%); in the cohort prepared according to the proposed protocol, in only 1 patient (4%). The mean score of BAT F-18-FDG uptake evaluated with the 4-point system was 0.04 in the group treated according to the new protocol and 0.16 in the group treated according to the previous protocol. Conclusion: In the clinically relevant group of breast cancer patients, F-18-FDG uptake in BAT can be reduced by a single oral administration of diazepam combined with controlled room temperature in resting rooms.