The use of FDG-PET in the detection and management of malignant lymphoma: correlation of uptake with prognosis.

Twenty-one patients with untreated malignant lymphoma in the head and neck region were evaluated with positron emission tomography (PET) using fluorine-18-fluorodeoxyglucose (FDG) and gallium-67 SPECT imaging. Tumor-to-normal soft-tissue contrast ratios (TCRs) obtained 60 min after injection of FDG were higher than 2.6, and all malignant lymphomas were clearly visualized. In patients with poor prognosis, higher TCRs and glucose utilization rates (GURs) were observed, whereas low TCR and GUR were shown in a patient with low-grade malignancy. In comparison with 67Ga scintigraphy, patients with high TCRs and GURs were likely to show increased accumulation of gallium-67, but accumulation of gallium-67 was not increased as much as FDG in poor prognostic patients. FDG-PET may be useful in the detection and management of malignant lymphoma.