18F-FDG Avidity in Lymphoma Readdressed: A Study of 766 Patients

PET/CT with 18 F-FDG is an important noninvasive diagnostic tool for management of patients with lymphoma, and its use may surpass current guideline recommendations. The aim of the present study is to enlarge the growing body of evidence concerning 18 F-FDG avidity of lymphoma to provide a basis for future guidelines. Methods: The reports from 18 F-FDG PET/CT studies performed in a single center for staging of 1,093 patients with newly diagnosed Hodgkin disease and non-Hodgkin lymphoma between 2001 and 2008 were reviewed for the presence of 18 F-FDG avidity. Of these patients, 766 patients with a histopathologic diagnosis verified according to the World Health Organization classification were included in the final analysis. 18 F-FDG avidity was defined as the presence of at least 1 focus of 18 F-FDG uptake reported as a disease site. Nonavidity was defined as disease proven by clinical examination, conventional imaging modalities, and histopathology with no 18 F-FDG uptake in any of the involved sites. Results: At least one 18 F-FDG―avid lymphoma site was reported for 718 patient studies (94%). Forty-eight patients (6%) had lymphoma not avid for 18 F-FDG. 18 F-FDG avidity was found in all patients (100%) with Hodgkin disease (n = 233), Burkitt lymphoma (n = 18), mantle cell lymphoma (n = 14), nodal marginal zone lymphoma (n = 8), and lymphoblastic lymphoma (n = 6). An 18 F-FDG avidity of 97% was found in patients with diffuse large B-cell lymphoma (216/222), 95% for follicular lymphoma (133/140), 85% for T-cell lymphoma (34/40), 83% for small lymphocytic lymphoma (24/29), and 55% for extranodal marginal zone lymphoma (29/53). Conclusion: The present study indicated that with the exception of extranodal marginal zone lymphoma and small lymphocytic lymphoma, most lymphoma subtypes have high 18 F-FDG avidity. The cumulating evidence consistently showing high 18 F-FDG avidity in the potentially curable Burkitt, natural killer/T-cell, and anaplastic large T-cell lymphoma subtypes justifies further investigations of the utility of 18 F-FDG PET in these diseases at presentation.