While a great deal of work has been performed concerning the impact of [18F]-FDG imaging in isolated lung lesion(s), there are still very few data about its role in case of isolated pleural lesions. The aim of this preliminary study was to shed some light on the utility of [18F]-FDG imaging, using PET or CDET detection, in this context.
Patients and method: Sixteen patients referred for apparently isolated pleural lesions were included in this study, since their 22 [18F]-FDG examinations were evaluable on bases of histology (9 cases), rapid disease progression (4 cases) or a follow-up period of more than 6 months (9 cases). Twelve [18F]-FDG examinations were performed with a dedicated PET machine (C-PET, Adac) and ten with a coincidence detection gamma camera (Irix, Picker). The precise clinical settings were the following: characterization of pleural masses or search for the unknown primary tumor in case of adenocarcinoma (6 cases), staging of a mesothelioma (5 cases), suspicion of recurrence and/or residual lesions (11 cases).
Results: The malignant pleural lesions took up [18F]-FDG in all cases. There was one false positive result due to an inflammatory lesion. False negative results for the detection of lymph node invasion occurred in three patients and were in relation with their infracentimetric size and the difficulty to distinguish on [18F]-FDG images mediastinal lymph nodes from widespread pleural and pulmonary extension of cancer. A change in patient management resulted from the [18F]-FDG examination in 4 patients (25%) and the course confirmed that the change was correct. Unknown lesions or active lesions wrongly considered residual that could have modified the management were discovered in 3 other patients.
Conclusions: This study highlights the fact that [18F]-FDG imaging has an impact on the management of patients with solitary pleural lesions and can detect recurrences, in some cases even more accurately than invasive procedures with histology. In our limited experience, the lack of anatomical details of the PET images is a major drawback in this setting and we are convinced that PET-CT will substantially enhance the impact of [18F]-FDG imaging.