Simple Pulmonary Eosinophilia Evaluated by Means of FDG PET: the Findings of 14 Cases

OBJECTIVE: We wanted to describe the findings of simple pulmonary eosinophilia with using 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). MATERIALS AND METHODS: We analysed the findings of 14 patients who underwent thoracic computed tomography (CT) and PET, and then they were subsequently proven to have simple pulmonary eosinophilia. PET studies were performed in four patients with malignancy to evaluate for cancer metastasis, and PET scans were also done in 10 healthy subjects who underwent volunteer cancer screening. The PET scans were evaluated by using the maximum standardized uptake values (SUVs). The subjects' CT findings also were reviewed and correlated with the PET findings. RESULTS: A total of 42 nodules were detected on the CT scans. There were single nodules in three patients and multiple nodules in 11 patients (mean number of nodules: 3, range: 1-10, mean diameter: 9.5 mm ± 4.7). Twelve of 42 (28.6%) nodules showed FDG uptake and their mean maximum SUV was 2.5 ± 1.6 (range: 0.6-5.3). Five of six solid nodules showed FDG uptake (2.2 ± 1.1, range: 0.9-3.6), six of 11 semisolid nodules showed FDG uptake (3.1 ± 1.8, range: 0.6-5.3) and one of 25 pure ground-glass opacity nodule showed a maximum SUV of 0.8. The maximum SUVs of seven nodules in five patients were greater than 2.5. The maximum SUVs were significantly different according to the nodule types (p < 0.001). CONCLUSION: Simple pulmonary eosinophilia commonly causes an increase in FDG uptake. Therefore, correlation of the PET findings with the CT findings or the peripheral eosinophil counts can help physicians arrive at the correct diagnosis of simple pulmonary eosinophilia.