Increased FDG uptake on 18F-FDG PET/CT in residual lesions of tuberculosis

<b>Background:</b> The optimal duration for treatment of TB likely differs between individuals depend on the resistance or the extent of the disease. 18F-FDG PET/CT correlates with treatment outcome in TB and could be useful as an early therapeutic marker. <b>Objectives:</b> To investigate the FDG uptake of TB lesions in the lung at the time of treatment completion <b>Methods:</b> Subjects with tuberculosis at treatment completion were enrolled and done 18F-FDG PET/CT within a week and followed-up for 2 years. <b>Results:</b> We enrolled 50 subjects. Of them, 11 was withdrawn, follow-up was done for 26 subjects for 2 years, 5 for a year, 4 for 6 months, and 4 for 3 months. Only one relapse was detected at 23 month after treatment completion. Among 39, male:female 30:9, new:retreatment 23:16, and average age was 56y-o (83-21). Six subjects have Diabetes and 29 were smokers(ex/current). The average treatment duration was 8.8 months(6-18) with first-line drugs for 31 patients and 24 months(18-34) with second-line drugs for 8 patients. Avid or enlarged mediastinal lymph nodes were shown in 12 subjects with variable SUVmax ranged from 2 to 5.4. The parenchymal lesions classified into 4 types: fibrotic lesion was observed in 27, nodular in 20, fibronodular in 10, but the infiltrations only in 3. The SUVmax greater than 3 was shown in 66%(2) of infiltrations, 45%(9) of nodular (3.1-5.6), 40%(4) of fibronodular (3.3-6.8) and 22%(6) of fibrotic lesions. The relapsed subject has 2 noduls and 2 infiltrations(86x48) with SUVmax 3.7 and 4.8 respectively. <b>Conclusion:</b> Among residual lesion types, the infiltration with higher SUVmax could be important type related to activity at treatment completion. More study with bigger population is needed.