Does the patient have recurrent lymphoma?
No, areas of uptake correspond with fat on CT.
Why does the fat take up FDG on this scan?
The fat represents brown fat, which as opposed to white fat, is metabolically active. The primary function of brown fat is thermoregulation, which is why it is activated when the patient is cold.
Where is brown fat typically located?
Supraclavicular, mediastinal, paraspinal, and retroperitoneal fat.
What measures can be taken to prevent this appearance on future PET-CT scans?
Keeping the patient warm before and during PET-CT scan. Premedication: propranolol, benzodiazepines (i.e., diazepam).
AC MIP: Extensive, intense uptake in the cervical, axillary, thoracic paraspinal, and retroperitoneal soft tissues.
Axial fused PET-CT and CT: In the supraclavicular region there is intense FDG uptake corresponding with regions of fat on CT.