The usefulness of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) and a comparison of 18F-FDG-PET with 67gallium scintigraphy in the evaluation of lymphoma -: Relation to histologic subtypes-based on the World Health Organization Classification

Background. Although studies comparing conventional imaging modalities with F-18-fluorodeoxyglucose positron emission tomography (F-18-FDG-PET) for the detection of lymphoma and although the relations between F-18-FDG-PET and histologic types were reported previously, most studies were not systematic and involved relatively small numbers of patients. Methods. Two hundred fifty-five patients with lymphoma had their disease staged using F-18-FDG-PET, and 191 of those patients also were assessed using gallium-67 scintigraphy (Ga-67). Disease sites were identified on a site-by-site basis using computed tomography scans and/or magnetic resonance imaging. The results of these conventional imaging modalities were compared with the results from F-8-FDG-PET and Ga-67, and correlations between the imaging results and pathologic diagnoses were evaluated by using the World Health Organization classification system. Results. Of 913 disease sites in 255 patients, F-18-FDG-PET identified >97% of disease sites of Hodgkin lymphoma (HQ and aggressive and highly aggressive non-Hodgkin lymphoma. For indolent lymphoma, the detection rate of F-18-FDG-PET was 91% for follicular lymphoma (FL); 82% for extranodal marginal zone B-cell lymphoma of mucosa- associated lymphoid tissue, irrespective of plasmacytic differentiation; and approximately 50% for small lymphocytic lymphoma (SLL) and splenic marginal zone lymphoma (SMZL). The results from Ga-67 were similar to those from F-18-FDG-PET for most histologic subtypes. However, the sensitivity of Ga-67 was unexpectedly poor for FL, for mantle cell lymphoma (MCL), and for the nasal type of natural killer/T-cell lymphoma (NK/T-nasal), ranging from 30% to 38%. Conclusions. F-18-FDG-PET was useful for all histologic subtypes of lymphoma other than SLL and SMZL. Compared with Ga-67, the authors strongly recommend the use of F-18-FDG-PET in patients with FL, MCL, and NK-nasal.