Capabilities of Positron Emission Tomography with 18F-fluorodeoxyglucose and 11С-methionine in Determining Pulmonary Tuberculosis Activity: Metabolic and Morphological Parallels
The aim of the investigation was to study the relationship between 18F-fluorodeoxyglucose (18F-FDG) and 11С-methionine accumulation levels and the activity degree of inflammatory process in patients with pulmonary tuberculosis using positron emission tomography (PET).
Materials and Methods. We analyzed the findings of multi-spiral computed tomography, PET with 18F-FDG and 11С-methionine in 45 operated patients with tuberculosis. Chest PET was performed according to a standard protocol, 120 min after 18F-FDG administration and 15 min after 11С-methionine injection. The processing of PET findings included visual image analysis and calculations Standardized Uptake Value (SUV) in an intact lung and tuberculoma area. In addition to radiological methods we used luminescent microscopy of sputum smear, culture sputum, and polymerase chain reaction. Tuberculosis morphological activity was assessed according to B.M. Ariel classification.
Results. According to laboratory techniques, bacterial activity of tuberculosis was found in 25 patients (55.5%). PET with 18F-FDG in all patients showed radiopharmaceutical hyperfixation focus in tuberculoma area that indicated the inflammatory process activity. In PET with 11С-methionine, the accumulation of radiopharmaceuticals in tuberculoma area was revealed only in 27 patients (60%). SUV analysis showed accumulation levels in PET with both radiopharmaceuticals to increase in proportion to the growth of tuberculosis activity rate.
Conclusion. Accumulation levels of 18F-FDG and, to a lesser degree, 11С-methionine reflect morphological activity of tuberculosis. Since 11С-methionine does not accumulate at all or accumulates in small amounts in I, II, III morphological activity tuberculomas, 11С-methionine is preferable to use to differentiate pulmonary cancer and tuberculosis. The informativeness of laboratory techniques in post-therapy tuberculosis activity determination is low.
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