18F-FDG PET imaging of progressive massive fibrosis

This study was to evaluate (18)F-FDG PET features of progressive massive fibrosis (PMF) and to determine the ability of FDG PET to differentiate pure PMF from PMF-associated lung cancer.

(18)F-FDG PET and chest computed tomography (CT) scans were performed in 9 patients with pneumoconiosis and PMF. Patients who showed active pulmonary tuberculosis on CT scan were excluded. Pure PMF was confirmed via either fine needle aspiration biopsy (n = 6) or 12 months follow-up CT scan (n = 3). CT features and PET findings were evaluated for distribution of fibrotic masses, consolidations, and nodules on CT scan and mean and maximum standardized uptake values (SUVs) of abnormalities depicted on PET scan.

14 masses were detected from nine patients. On chest CT scan, PMF masses were noted with surrounding small nodules and distortion of parenchyma. The size of the lesions ranged from 1.2 to 6.4 cm in maximum diameter. FDG PET scans identified metabolically active lesions in all patients. Maximal SUV ranged from 3.1 to 14.6 and mean SUV ranged from 1.4 to 8.5.

FDG PET can identify PMF lesions as hypermetabolic lesions even without associated malignancy or tuberculosis. Therefore, it might have a limited role in the diagnosis of PMF with possible concurrent granulomatous inflammation or lung cancer.