In the series reported in this communication, FDG-PET imaging has proved to be useful in localizing the areas involved with malignant mesothelioma. Although the limited number of subjects with benign disease precludes definitive statements about the specificity of this method, the sensitivity of FDG-PET imaging appears high, better than the reported sensitivity of CT-guided pleural biopsy. In difficult cases in which conventional imaging cannot clearly establish whether a pleural lesion is malignant, PET may be helpful in deciding whether to pursue the investigation with thoracoscopy or thoracotomy. Canadian pharmacy levitra website Other investigators have used FDG-PET imaging to identify underlying malignancies in cases of pleural effusion of unknown etiology, suggesting that this modality might prove helpful in this setting. However, it must be remembered that FDG measures tissue metabolic activity regardless of the underlying cause, and it is not a specific tumor marker. Potential causes of false-positive FDG-PET studies include sarcoidosis, tuberculosis, fungal infections, acute fractures, skeletal muscle trauma, and bacterial infections such as abscesses FDG-PET is also unable to differentiate mesothelioma from pleural adenocarcinoma, a task that challenges even expert pathologists. It is therefore important that specific tissue confirmation be obtained before the final diagnosis of mesothelioma is established. In patients with normal results of the study, careful follow-up should be considered as dictated by careful clinical assessment. Rarely, low-grade mesotheliomas may not be intensely hyper-metabolic on a PET study as shown in this report with two cases of minimally increased FDG uptake. Further studies will be needed to establish whether a normal PET study indicates a good prognosis in this setting.
FDG-PET imaging can be useful for accurate staging of the extent of disease involvement. This modality can be a useful adjunct to CT or MRI scanning, as these studies may not always reliably predict unresectability. This is illustrated by the first case (case A, detailed above), in which FDG-PET indicated potential resectability when the CT study incorrectly suggested mediastinal and contralateral involvement. Conversely, PET imaging frequently demonstrated more extensive disease involvement than that revealed by other imaging modalities, and in some cases, even more than that documented with thoracoscopy.