[Comparative analysis of the informative value of 18F-fluorodeoxyglucose and 11C-methionine positron emission tomography in the differential diagnosis of solitary lung masses].

OBJECTIVE: To study the possibilities of enhancing the efficiency of differential diagnosis of solitary lung masses by optimizing the quantitative analysis of positron emission tomography (PET) data when two radiopharmaceuticals (RP) (18F-fluorodeoxyglucose (18F-FDG) and 11C-methionine) are used alone and in combination.

MATERIAL AND METHODS: A comprehensive examination involving 18F-FDG and 11C-methionine PET was made in 116 patients with solitary lung masses of various genesis. A final diagnosis in the examinees was established from the results of postoperative material morphological analysis and/or laboratory tests and those of X-ray follow-up.

RESULTS: No 18F-FDG and 11C-methionine hyperfixation was found in patients with benign tumors and in the majority of patients with focal pneumofibrosis. At 18F-FDG and 11C-methionine PET, RP accumulation was recorded in all patients with lung cancer (LC) and in patients with inflammatory diseases. Three patients with 18F-FDG PET-negative typical carcinoid tumors were noted to have increased 11C-methionine uptake. At 11C-methionine PET, RP accumulation was recorded in the projection of formation in all the patients with LC and in 38 of the 42 patients with inflammatory diseases. Regardless of the used RP, the Standardized Uptake Value (SUV) was significantly lower in the patients with inflammatory diseases than in those with LC (p ≤ 0.05).

CONCLUSIONS: When RP is used alone, the diagnostic efficiency of C-methionine PET in the differential diagnosis of lung tumors and inflammations is higher than that of 18F-FDG PET. At the same time, the highest PET is seen when 18F-FDG and 11C-methionine are used in combination.