Computed tomography and F-18-FDG-positron emission tomography for staging lymphomas: a comparison

Purpose. To determine the value of F-18-FDG-positron emission tomography (FDG-PET) compared with computed tomography (CT) in the staging of malignant lymphomas. Material and method: 50 patients with biopsy-proven lymphoma were studied with FDG-PET and CT. The results in initial, posttherapeutic and staging of recurrence were compared. Results: 37 of 65 FDG-PET were identical with CT. 28 studies showed differences. 14 post-therapeutically and one of the initial studies led to downstaging by FDG-PET wereas upstaging resulted in one case of initial staging. In two cases false positive pulmonary FDG accumulations caused an upstaging. Conclusion: FDG-PET was at least comparable to CT in recording the extension of a newly diagnosed lymphoma or its recurrence. Upstaging according to FDG-PET occurred only once in initial staging. FDG-PET plays its most important role in the evaluation of residual mass in CT after therapy by accumulating FDG in viable tumour rather than in fibrotic tissue. 14 cases of downstaging according to FDG-PET resulted.