Clinical Significance of Increased FDG Uptake in the Waldeyer Ring and the Nasopharynx Region Identified by PET-CT in Postchemotherapy Follow-up in Patients With Lymphoma: When Should We Perform Biopsy?

ABSTRACT

PURPOSE: To identify whether fluorodeoxyglucose (FDG) uptake in the Waldeyer ring (WR)/nasopharyngeal (NP) region by positron emission tomography-computed tomography (PET-CT) was physiologic or pathologic in the follow-up of lymphoma patients receiving postchemotherapy treatment. PATIENTS AND METHODS: We retrospectively examined FDG uptake in the WR/NP region in 534 patients with lymphoma as assessed by PET-CT used for both diagnosis and follow-up. RESULTS: Forty-nine patients had FDG uptake in the WR/NP region by PET-CT performed after completion of a chemotherapy regimen. Biopsy was performed for 11 of these patients in whom the uptake was considered to be pathologic, and results indicated the presence of reactive follicular hyperplasia. It was considered to be physiologic in 38 patients. PET-CT was repeated after 1 year, and no significant difference was identified between the standardized maximum uptake values (SUVmax; P = .107). The initial diagnosis of 20 patients was made via biopsy performed in the WR/NP region. The SUVmax for the FDG uptake in these patients, asymmetry, SUVmax of the coexisting lymphadenopathies in the neck, and FDG uptake with a counterpart finding by CT were significantly higher than other groups (P = .047, .001, and .005). CONCLUSION: When deciding whether to resample after treatment completion, it should be taken into account that, in addition to the SUVmax of the lesion, asymmetry, and the SUVmax of the coexisting lymphadenopathy in the neck, a crucial criterion is whether the FDG uptake has a counterpart finding by CT.