Introduction: The clinical applications of fluorine-18-deoxyglucose Positron Emission Tomography (FDG PET) have been proposed on account of experimental evidence of increased glucose metabolism in tumor cells.
Material and methods: We examined 98 lymphoma patients--33 with Hodgkin and 65 with non-Hodgkin disease--with FDG PET and compared its findings with those of clinical and conventional radiologic studies. FDG PET was also used to follow-up 32 patients and the results were once again compared with clinical and radiologic data.
Results: During staging, 138 lesions were found, 82 of them (59%) in nodal and 56 (41%) in extranodal locations. Extranodal tumor sites were found in 39 patients (40%), namely 4 with Hodgkin (12%) and 35 with non-Hodgkin (54%) disease. FDG PET findings were in agreement with clinical and radiologic results in all nodal and extranodal lesions, since all of them exhibited abnormally increased FDG uptake. PET detected new tumor sites in 6 patients. In the follow-up, agreement was observed in the majority (78%) of lesions, 30 of them in complete regression, 15 in partial regression and 17 in progression; however, the diagnostic results were in disagreement in the remaining (22%) tumor sites: no abnormal FDG uptake was found in 9 cases despite the persistence of radiologic abnormalities (post-treatment fibrosclerosis). Slightly increased FDG uptake (residual disease) was found in the other 8 lesions, where there was no clinical and/or radiologic evidence of disease.
Conclusions: FDG PET is a functional imaging technique useful to diagnose lymphomas and providing metabolic characterization of cancer abnormalities. Whole body PET permits the simultaneous assessment of nodal and extranodal lymphoma localizations. During the follow-up, FDG PET permits better monitoring of treatment effects than clinical and radiologic examinations.