Clinical relevance of positron emission tomography (PET) in treatment control and relapse of Hodgkin's disease

Background: In Hodgkin's disease accurate restaging is important to assess treatment results and may eventually provide a basis for further therapeutic strategies. A typical dilemma after treatment of Hodgkin's disease with radiographically persistent lymphoma is the differentiation between sterilized residual mass and viable tumor. Positron emission tomography (PET) has been described as a reliable tool to identify active Lymphoma. Aim of the present study was to assess the accuracy and clinical relevance of PET for treatment control and in the situation of a suspected relapse of Hodgkin's disease. Patients and Methods: 63 patients (32 men, 31 women, mean age 41.5 years) with Hodgkin's disease were investigated with FDG-PET. In 51 patients 63 PET studies were performed as a treatment control(group 1) after primary therapy. 17 patients (5 of whom pre-examined in group 1) underwent 18 PET scans for confirmation of suspected relapse (group 2). PET was performed with a dedicated whole-body ring scanner. In a retrospective analysis, all FDG-PET scans were compared with conventional imaging methods and related to the final diagnosis obtained by histology and/or clinical follow-up (mean 22.4 months). Results: Group 1: FDG-PET showed an accuracy of 91%, whereas the accuracy of conventional imaging was 62%. Group 2: The accuracy for PET was 83% and 56% for conventional imaging. Conclusion: The present data suggest that PET is a sensitive and reliable tool for detection of involved areas of active Hodgkin's disease. The accuracy of PET for restaging purpose seems to be superior than conventional imaging.