Utility of Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) Imaging for Evaluating Treatment Efficacy in Mycobacterium avium Complex Pulmonary Disease

Introduction <i>Mycobacterium avium</i> complex pulmonary disease (MAC-PD) necessitates prolonged treatment. However, determining the appropriate time to conclude treatment is challenging because of the lack of indices for evaluating disease activity. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can be used to visualize inflammatory sites and is hypothesized to indicate treatment efficacy in inflammatory diseases. Therefore, we conducted this single-arm, open-label, interventional study to investigate the utility of FDG-PET/CT imaging as an indicator of treatment efficacy by analyzing the correlation between pre- and post-treatment FDG-PET/CT imaging and treatment efficacy in MAC-PD. Methods FDG-PET/CT scans were performed before and 52 weeks after the initiation of MAC-PD treatment to assess the utility of FDG-PET/CT as an indicator of treatment efficacy. The primary endpoint was the association between treatment efficacy/culture-negative conversion and the standardized uptake value (SUV) max, SUV peak, target/background ratio (TBR), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). Results Ten patients were enrolled after obtaining informed consent, and comparative evaluation after one year of treatment was feasible in nine patients. Based on predefined comprehensive clinical endpoints (symptoms, imaging, and inflammatory findings), five cases were deemed effective, and four cases were deemed ineffective. The effective cases exhibited a significantly lower SUV peak and TBR in the pre- and post-treatment ratios than the ineffective cases. However, no statistically significant associations were observed between these indices and culture-negative conversions. Conclusion These findings suggest that the pre- and post-treatment ratios of SUV peak and TBR may be valuable for evaluating disease activity in patients with MAC-PD.