Potential false positive active extra pulmonary tuberculosis lesions on FDG PET/CT imaging in malignancy.

Objectives: Integrated fusion imaging modality Positron Emission Tomography Computed Tomography (PET/CT)using 18Fluorine-Fluoro Deoxy Glucose (18F-FDG) iscommonly utilized in imaging oncology. We expand therole of this imaging modality in our study to demonstratethe appearance of active extra pulmonary tuberculosis(TB) lesions. Materials and methods: This study involved prospective evaluation of 8 patients using 18F-FDG PET/CT with confirmed diagnosis of extra pulmonary TB infection. Visually high intensity lesions in abnormal areas were studied where the mean and maximum standardized uptake value (SUVmean and SUVmax) were tabulated. The diagnosis of TB infection was confirmed by isolation of TB bacillus from these lesions or evidence of responding to anti TB treatment during post treatment evaluation using FDGPET/ CT at follow up.Results: The genders are equally affected. Majority of the group falls within young age below 50 years. Number of PET/CT studies demonstrating lesions either singly or multiple were equal in distribution. Nodal involvement is commonest in our study including mediastinum, paraaorticand inguinal groups. Other sites of infection includespine and bowel. The average SUVmax and SUVmean for alllesions were 7.7 and 5.2 respectively. Conclusion: Active TB lesions are FDG avid. Thus, FDGavid lesions should be interpreted with extra careful whenFDG PET / CT is utilized in managing malignancy