Objective: To evaluate the clinical value of (18)F-FDG PET/CT in the differentiation between benign lesions and lung cancer for large shadows in patients with pneumoconiosis.
Methods: A retrospective study was conducted in 21 patients with a confirmed diagnosis of pneumoconiosis who had a total of 37 large shadows in the lung fields as shown by whole-body (18)F-FDG PET/CT imaging, and (18)F-FDG uptake was evaluated using the maximum standardized uptake value (SUVmax). Twelve lesions were examined by CT-guided aspiration biopsy, and one case underwent fiberoptic bronchoscopy, as well as tests based on bronchoalveolar lavage fluid and sputum; the other cases were followed up for more than 2 years. The differences between pneumoconiosis nodules with high (18)F-FDG uptake and lung cancer were evaluated by t test.
Results: Seventeen lung masses or nodules with high (18)F-FDG uptake were detected in 13 patients; among the 13 patients, 5 lesions of 5 cases were confirmed as non?small cell lung cancer (1 case of squamous cell carcinoma, 3 cases of adenocarcinoma, and 1 case of recurrent squamous cell carcinoma after operation), and 7 lesions of 7 cases were progressive massive fibrosis as shown by CT-guided aspiration biopsy; one case had no tumor cells detected by fiberoptic bronchoscopy, and 2.5-year follow-up revealed no changes in the lesions. The other 8 patients showed no increased (18)F-FDG uptake in their 20 lung nodules, which were confirmed as benign lesions by follow-up. The diameter range of lung cancer was 1.6∼6.8 cm, and the SUVmax range was 4.8∼14.0; the diameter range of pneumoconiosis nodules with high (18)F-FDG uptake was 1.5∼4.6 cm, and the SUVmax range was 2.6∼12.4. There were no significant differences in diameter and SUVmax between the lung cancer and pneumoconiosis nodules with high (18)F-FDG uptake (P > 0.05 for both). (18)F-FDG PET/CT had a specificity of 62.5% (20/32), an accuracy of 67.6% (25/37), a false-positive rate of 37.5% (12/32), and a negative predictive value of 100% (20/20) for the diagnosis of lung cancer. The lung cancer detection rate was 23.8% (5/21).
Conclusion: In (18)F-FDG PET/CT imaging for patients with pneumoconiosis, the lung lesions without (18)F-FDG uptake or symmetrical lesions with high (18)F-FDG uptake are considered as benign pneumoconiosis nodules; however, (18)F-FDG PET/CT might have a limited role in evaluating the solitary lung lesions in patients with pneumoconiosis and needs further study.