Which of the following is the likely explanation for symmetrical uptake in bilateral supraclavicular areas with no uptake on paratracheal nodes on PET-CT in a patient with ca esophagus?

Ans. A. Brown adipose tissue18F-FDG PET-CT is the current modality of choice to evaluate for metastases and demonstrates brown fat as areas of high uptake.It is a potential source of false-positive FDG PET interpretations in oncologic imaging.18F-FDG is highly accumulated in hypermetabolic fat as the glucose, even if not as a direct source of heat production but as a source of adenosine triphosphate, which is required for heat production.Areas of Normal physiological uptake in PET CT:# Brain tissue# Skeletal muscle, especially after strenuous activity and laryngeal muscles following speech# Myocardium# Gastrointestinal tract, e.g. intestinal wall# Genitourinary tract: FDG is excreted via the renal system and passes into the collecting systems# Brown fat# Thymus# Bone marrow