The usefulness of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) and a comparison of (18)F-FDG-pet with (67)gallium 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 (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) for the detection of lymphoma and although the relations between (18)F-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 (18)F-FDG-PET, and 191 of those patients also were assessed using gallium-67 scintigraphy ((67)Ga). 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 (8)F-FDG-PET and (67)Ga, 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, (18)F-FDG-PET identified >97% of disease sites of Hodgkin lymphoma (HL) and aggressive and highly aggressive non-Hodgkin lymphoma. For indolent lymphoma, the detection rate of (18)F-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 (67)Ga were similar to those from (18)F-FDG-PET for most histologic subtypes. However, the sensitivity of (67)Ga 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: (18)F-FDG-PET was useful for all histologic subtypes of lymphoma other than SLL and SMZL. Compared with (67)Ga, the authors strongly recommend the use of (18)F-FDG-PET in patients with FL, MCL, and NK-nasal.