A Prospective Study of 18F-FDG PET-CT Application in Therapeutic Monitoring of Osteoarticular Tuberculosis

Abstract

Objective: Confident diagnosis, identification of occult sites, assessing treatment response, and precisely ascertaining the duration and endpoint of treatment in skeletal tuberculosis is often challenging. magnetic resonance imaging (MRI) and computed tomography (CT) are less dependable owing to low sensitivity and the inability to discern current illness and old changes. 18F-FDG PET/CT utilizes variations in glycolysis rates between healthy and diseased tissue to quantitatively estimate the maximal standard uptake value (SUVmax) of 18F-FDG to assess disease activity.Material and Methods: 32  patients who presented to the department with a clinicoradiological suspicion and pathologically proven diagnosis of skeletal tuberculosis were prospectively analyzed. All patients underwent a whole body 18F-FDG PET-CT scan before initiation of anti-tubercular therapy (ATT), and then treatment was started as per the Revised National Tuberculosis Control Program (RNTCP) guidelines. All patients were followed up with repeat PET-CT scans and relevant clinical investigations at 2, 6, and 12 months.Results: A gradual decrease in SUVmax values, as the treatment courses progressed indicated a decrease in disease activity with treatment. There was an overall mean decrease of 6.5 units in the SUVmax values when compared to the pre-treatment levels, which was statistically significant (p-value<0.001).  At 2 months of anti-tubercular treatment, the mean SUVmax values decreased by 39%, and at 6 and 12 months of ATT, they were reduced by 60% and 81%, respectively.Conclusion: 18F-FDG PET-CT helps to determine the prevalence of occult multifocal activity elsewhere in the body. The gradual decrease in SUVmax values during the course of ATT is a useful tool to assess disease response and to precisely decide the endpoint of ATT.