18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging features in patients with non-tuberculous mycobacterial infection

Abstract

Objectives: Non-tuberculous mycobacterial (NTM) infection is a growing public health concern. Due to atypical clinical symptoms and poorly defined radiological findings, NTM is often misdiagnosed, resulting in treatment delay. The aim of the present study was to analyze the findings of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan imaging in patients with NTM infection in order to improve the diagnosis and treatment of NTM disease.Methods: A total of 23 patients with confirmed NTM infection who underwent 18F-FDG PET/CT scan imaging were retrospectively analyzed. The data on clinical and 18F-FDG PET/CT imaging characteristics were reviewed. The 18F-FDG PET/CT images were analyzed both qualitatively and quantitatively using maximum standardized uptake value (SUVmax), SUVMax (the most FDG-avid lesion in the whole body), SURLiver and SURBlood (SUVMax ratio of lesion-to-liver and lesion-to-blood pool). The optimal cut-off of 8F-FDG was determined using receiver operating characteristic curve (ROC).Results: Subgroup analysis showed significant differences in metabolic parameters of 18F-FDG-avid lesions, including SURLiver, SURBlood, and SUVMax among the three groups with different immunological states (p = 0.007, 0.012, and 0.010, respectively). The cut-off point of 3.8 for SURLiver showed the best equilibrium between sensitivity and specificity (52.9% and 83.3%). In terms of the NTM lesion distribution, there were significant differences in SURLiver, SURBlood, and SUVMax between the localized and disseminated groups (p = 0.003, 0.009, and 0.005, respectively). The cut-off point of 3.3 for the SUVBlood had high specificity (87.5%) and sensitivity (71.4%). Furthermore, in terms of NTM lesion severity, SUVmax of lung lesions (SUVI-lung), SUVmax of marrow (SUVMarrow), and platelet count significantly differed between severe and non-severe groups (p = 0.036, 0.006, and 0.007, respectively). When the cut-off values of SUVMarrow and SUVI-lung were set at 3.1 and 4.6, the sensitivity was 76.9% and 76.9%, respectively, while the specificity was 88.9% and, 55.9%, respectively.Conclusion: In patients with NTM infection, 18F-FDG PET/CT is a unique and powerful tool in the diagnosis and evaluation of disease activity, immunological state, and extent of lesion involvement and it can help determine the appropriate treatment for NTM infection.