The additional value of 18 F-FDG PET/CT imaging in guiding the treatment strategy of non-tuberculous mycobacterial patients.

OBJECTIVES: Non-tuberculous mycobacteria (NTM) infection is an increasing health problem due to delaying an effective treatment. However, there are few data on 18 F-FDG PET/CT for evaluating the status of NTM patients. The aim of this study was to investigate the potential value of 18 F-FDG PET/CT in guiding the treatment strategy of NTM patients.

METHODS: We retrospectively analyzed the cases of 23 NTM patients who underwent 18 F-FDG PET/CT. The clinical data, including immune status and severity of NTM pulmonary disease (NTM-PD), were reviewed. The metabolic parameters of 18 F-FDG included maximum standardized uptake value (SUVmax ), SUVmax of the most FDG-avid lesion (SUVTop ), SUVTop /SUVmax of the liver (SURLiver ), SUVTop /SUVmax of the blood (SURBlood ), metabolic lesion volume (MLV), and total lesion glycolysis (TLG). The optimal cut-off values of these parameters were determined using receiver operating characteristic curves.

RESULTS: There were 6 patients (26.09%) with localized pulmonary diseases and 17 patients (73.91%) with disseminated diseases. The NTM lesions had high or moderate 18 F-FDG uptake (median SUVTop : 8.2 ± 5.7). As for immune status, the median SUVTop in immunocompromised and immunocompetent patients were 5.2 ± 2.5 and 10.0 ± 6.4, respectively, with a significant difference (P = 0.038). As for extent of lesion involvement, SURLiver and SURBlood in localized pulmonary and disseminated diseases were 1.9 ± 1.1 vs. 3.8 ± 1.6, and 2.7 ± 1.8 vs. 5.5 ± 2.6, respectively, with a significant difference (P = 0.016 and 0.026). Moreover, for disease severity, SUVmax of the lung lesion (SUVI-lung ) and SUVmax of the marrow (SUVMarrow ) in the severe group were 7.7 ± 4.3 and 4.4 ± 2.7, respectively, significantly higher than those in the non-severe group (4.4 ± 2.0 and 2.4 ± 0.8, respectively) (P = 0.027 and 0.036). The ROC curves showed that SUVTop , SURLiver , SURBlood , SUVI-lung , and SUVMarrow had a high sensitivity and specificity for the identification of immune status, lesion extent, and severity of disease in NTM patients.

CONCLUSION: 18 F-FDG PET/CT is a useful tool in the diagnosis, evaluation of disease activity, immune status, and extent of lesion involvement in NTM patients, and can contribute to planning the appropriate treatment for NTM.