Purpose: To evaluate the usefulness of positron emission tomography with F-18-fluorodeoxyglucose(FDG-PET)for differentiation between infectious disease (tuberculous lymphadenitis) and malignant neoplasm (malignant lymphoma and lymph node metastases) in patients with multiple lymphadenopathy on Computed Tomography (CT) and Magnetic Resonance (MR) images.

Methods and Materials: We examined FDG-PET study in 101 patients(tuberculous lymphadenitis:5 patients, malignant lymphoma:13 patients,lymph node metastases:83 patients) with multiple lymphadenopathy between January 2001 and February 2003. Standardized Uptake Value(SUV) for tuberculous lymphadenitis, malignant lymphoma and lymph node metastases were calculated and compared in each group. Histological diagnoses of lymphadenopathy were based on the pathological findings of resected specimens and/or biopsied specimens. At least one site of lymph node in 101 patients was visualized on FDG-PET images. A region of interest (ROI) was drawn on the lymph node with highest FDG uptake in each patient, and its maximum SUV in the ROI was assessed max-SUV.

Results: We found a statistically significant difference in the max-SUV of lymphadenopathy between the tuberculous lymphadenitis (SUV:3.7±0.9) and the malignant neoplasm (SUV:7.1±2.1) including malignant lymphoma(SUV:7.0±3.4), lymph node metastases(SUV:7.1±2.8)(p<0.01, the nonparametric Mann-Whitney U test).

Conclusion: SUV analysis of FDG-PET seems to be a useful method for differentiation between infectious disease (tuberculous lymphadenitis) and malignant neoplasm (malignant lymphoma and lymph node metastases) in patients with multiple lymphadenopathy on CT/MR images.