Figure 14b. Residual disease in a 36-year-old man with a history of Hodgkin disease who was referred for postchemotherapy evaluation. (a-c) Coronal PET scan (b) shows symmetric hypermetabolic foci in the cervical and supraclavicular regions (small arrows). In addition, there is asymmetric uptake in the right axillary region (large arrow). Coronal CT (a) and PET-CT fusion (c) images help confirm persistent lymphoma in the right axillary lymph nodes (large arrow). No abnormality is seen in the cervical supraclavicular regions that corresponds to the FDG uptake in these regions (small arrows), a finding that is consistent with brown adipose tissue. (d-f) Axial PET scan (e) demonstrates multiple foci of increased FDG uptake in the cervical region. There is also a unilateral focus of uptake in the right jugular region (arrow) that is suspicious for malignancy. CT (d) and PET-CT fusion (f) images help confirm that the focal FDG uptake on the right side (arrowhead) corresponds to a jugular lymph node, a finding that is consistent with residual Hodgkin disease. The uptake in the brown adipose tissue renders interpretation difficult by obscuring the underlying lymph nodes that harbor viable residual disease. It is essential that this pattern of uptake be evaluated simultaneously with CT.