Residual Fdg Metabolic Activity And Its Prognostic Value For Disease Relapse Among Patients Treated For Pulmonary Tuberculosis

296 Background: FDG PET/CT imaging at the completion of anti-tuberculosis therapy (ATT) may show residual metabolically activity (RMA) in patients considered cured at end of treatment (EOT) based on current standard of care diagnostic definitions. The significance of RMA as a risk factor for relapse is currently unknown. This study aimed to determine the prevalence of residual metabolic activity (RMA) by FDG PET/CT scanning in EOT tuberculosis (TB) patients and the value of RMA for predicting relapse in this patient cohort. Methods: Fifty-three TB patients who complied with a six-month standard regimen of ATT for drug-susceptible pulmonary tuberculosis and were declared cured based on negative clinical assessment and sputum microbial culture were recruited to undergo EOT FDG PET/CT. A monthly follow-up home visit was paid to each participant to screen for newly emerging symptoms of tuberculosis (TB). If present, repeat bacteriological tests were performed to confirm recurrent disease. We determined the prevalence of RMA on EOT PET/CT from the proportion of patients who experienced a relapse during 6-month follow-up. Results: The mean age of the 53 study participants was 37.81 ± 11.29 years. RMA was seen in 33/53 patients with a median SUVmaxof 3.83 (IQR:3.01-5.39). Patients with RMA on FDG PET imaging were slightly younger compared with those with complete metabolic response (CMR), 38.85 ± 12.13 versus 36.1 ± 9.79 years respectively. Males were slightly more likely to have RMA (21/33) compared with females (12/20). Cavitatory lesions were seen in 23 patients, 18 of whom had RMA while 5 had CMR. Presence of cavitatory TB was a significant predictor of RMA (P=0.035). Serum hemoglobin, C-reactive protein level, body mass index, smoking history were not significant predictors of RMA (P>0.05). During the 6-month follow-up, 10% with RMA had developed TB relapse. No patients with CMR (n=20) had developed relapse. Conclusion: There was a high prevalence of RMA seen on EOT FDG PET/CT imaging among TB patients who are considered cured after completion of ATT (62%). Cavitation is predictive of RMA at the end of treatment. Our study showed that TB patients with RMA on EOT FDG PET/CT are at increased risk of disease relapse within 6 months after completion of treatment.