Usefulness of 18F-fluorodeoxyglucose positron emission tomography for diagnosing disease activity and monitoring therapeutic response in patients with pulmonary mycobacteriosis

Purpose  To evaluate the usefulness of ¹⁸F-FDG PET in the imaging of pulmonary lesions related to disease activity and in monitoring responses to treatment in patients with pulmonary mycobacteriosis (PM). Materials and methods  We used high-resolution computed tomography (HRCT) and ¹⁸F-FDG PET to evaluate 47 consecutive untreated patients with PM, 25 with tuberculosis (TB) and 22 with Mycobacterium avium-intracellulare complex (MAC), who presented with small peripheral pulmonary nodules ≤3 cm, and compared the findings. The diagnosis of mycobacteriosis was confirmed by bacteriological examinations of bronchoscopic or surgically resected specimens. PET scans were visually and quantitatively analysed using SUVmax. In addition, 14 patients with PM underwent repeat PET scanning during antimycobacterial therapy, and changes in ¹⁸F-FDG uptake were clinically evaluated (6 during treatment and 12 after treatment). Results  Of all the lesions, 87.2% had SUVmax levels ranging from 3 to 7 (5.05 ± 1.56, range 2.5–7.6, n = 47). Further, SUV levels in patients with PM reflected disease activity as estimated by HRCT, but did not differ significantly between those with TB (4.96 ± 1.61, n = 25) and MAC (5.15 ± 1.53, n = 22). ¹⁸F-FDG uptake was significantly decreased in all 14 patients who received chemotherapy, indicating a positive response to treatment. Conclusion   ¹⁸F-FDG PET is considered to be useful for the diagnosis and evaluation of disease activity along with HRCT findings, and in monitoring response to chemotherapy in patients with PM.