Role of 18FDG-PET/CT in detecting relapse during follow-up of patients with Hodgkin's lymphoma

The role of 18FDG-PET/CT during follow-up of patients affected by Hodgkin's lymphoma (HL) in complete remission after treatment is not fully elucidated, since a wide use of 18F fluorodeoxyglucose positron emission tomography/computed tomography (18FDG-PET/CT) in this setting could be limited by a relative high rate of false-positive results. Herein, we summarize a retrospective analysis of 27 patients with Hodgkin's lymphoma in complete remission after the first-line (n = 20) or salvage (n = 7) therapy receiving serial 18FDG-PET/CT scans during follow-up. Out of 165 scans, 13 were suspected for relapse, which was confirmed in seven patients. All relapses were correctly identified by 18FDG-PET/CT positivity, with a 100% sensitivity; false-positive rate was 46% and negative predictive value was 100%. True-positive findings were mostly associated with multiple sites, subdiaphragmatic involvement, and/or previous sites of disease. According to our results, we conclude that performing routine PET/CT scan during follow-up of those patients who are at high risk of relapse would be advisable, although caution must be adopted when interpreting PET/CT results due to the relatively high rate of false-positive findings. If FDG abnormal uptake is present at multiple nodal sites, subdiaphragmatic lymph nodes, or previous sites of disease, histological verification of PET abnormal findings is warranted.