Figure 16bxy. FDG uptake in noncancerous lymph nodes. (a) Axial FDG PET image of a patient with a treated lung abscess shows FDG uptake in intrapulmonary lymph nodes (arrows). Even though the lung abscess is no longer FDG avid, the inflammatory response in the regional lymph nodes and the associated FDG uptake remain. (b) Axial FDG PET images (shown from superior [top left] to inferior [bottom right]) of a patient with a cavitating primary lung neoplasm (open arrow) and adjacent organized pneumonia show FDG uptake in paratracheal and precarinal lymph nodes (solid arrows). The FDG-avid nodes did not harbor metastases but rather an inflammatory response to the regional pneumonia. Note the FDG uptake along the tract formed by a previously placed chest tube (arrowheads). (c) Contrast material–enhanced CT scan of the same patient as in b shows an enlarged precarinal lymph node (solid arrow) and the chest tube tract (open arrow).