Seventy FDG-PET/CT Cases in Which Nuclear Medicine Physicians Suspected Lymphoma: How Reliable Are We?

OBJECTIVE(S): To validate the reliability of nuclear medicine physicians in diagnosing lymphoma using positron emission tomography/computed tomography using 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG-PET/CT) and to determine findings that reliably suggest lymphoma. METHODS: Seventy patients suspected of having lymphoma using FDG-PET/CT were enrolled in this retrospective study. Two nuclear medicine physicians read all the interpretation reports and graded the degree of suspicion by consensus (3: definitely suspicious, 2: probably suspicious, and 1: possibly suspicious). The following factors were also investigated for each patient: maximum standardized uptake value (SUV(max)) of the lesions, serum level of soluble interleukin-2 receptor (sIL-2R), and the presence of splenic FDG uptake higher than that of the liver. RESULTS: The study group consisted of 34 lymphomas, 18 other malignancies, and 18 benign lesions according to histopathological diagnosis. No patient with a Grade 1 degree of suspicion was diagnosed as lymphoma. SUV(max) and the serum level of sIL-2R could not distinguish lymphoma from other diseases. Of the 11 patients who presented with elevated splenic FDG uptake, 10 were diagnosed as having lymphoma. CONCLUSION: When the degree of suspicion by nuclear medicine physicians is low, the possibility of lymphoma is also low. On the other hand, elevated splenic FDG uptake may suggest lymphoma.