DIAGNOSTIC UTILITY OF PET/CT WITH 11C-METHIONINE IN PATIENTS WITH LYMPHOMAS

Abstract

Aim: to study the role of combined positron emission and computed tomography (PET/CT) with 11C-methionine in the diagnosis of patients with different types of lymphoma. Material and methods. Uptake of 11C-methionine and 18F-FDG was studied with PeT/CT in 24 patients with histologically verified lymphoma. All patients underwent studies with both radiopharmaceuticals. A total of 48 studies were performed. Results. All 24 patients had abnormal sites of pathological uptake of 11C-methionine and 18F-FDG. Regions of abnormal sites of metabolic activity were coinciding in examinations with both radiopharmaceuticals. The average uptake rate of 18F-FDG and 11C-methionine were 9,45 ± 1,3 and 6,7 ± 0,4, (p = 0,05) respectively. In patients with Hodgkin's lymphoma (HL) and aggressive non-Hodgkin's lymphoma (NHL) in comparison with indolent NHL patients the metabolic activity of the pathological focuses in examinations with both radiopharmaceuticals had a significant difference in the accumulation rate, depending on the degree of malignancy-p = 0,01 and p = 0,001, respectively. The sensitivity and specificity of PET/CT with 11C-methionine was 94,4% and 83,3%, respectively. The threshold value of SUVmax > 5,6 (p <0,0001), allows to differentiate lymphomas according to the degree of malignancy. Conclusion. Most sites of tumor involvement in patients with HL and NHL well visualized using 11C-metnionine PET/ CT. All tumor sites had a different level of metabolic activity, higher in patients with aggressive NHL and HL. However it's utility in the abdomen is limited by uptake in normal structures.