Is FDG-PET/CT useful for managing malignant pleural mesothelioma?

Imaging techniques such as CT, MRI and PET/CT have essential pre- and post-treatment roles in detecting tumors and evaluating the extension of malignant pleural mesothelioma (MPM). We sough to evaluate the advantages and limitations on FDG-PET/CT findings.

We performed 13 FDG-PET/CT studies in 9 patients with MPM (8 males, 1 female, aged 51 to 84 years, 9 at the initial diagnosis, 4 follow up studies). We reviewed FDG-PET/CT findings of primary tumors, recurrent tumors, lymph nodes, metastasis.

All primary and recurrent tumors were FDG positive. The uptake patterns at initial diagnosis were; diffuse+multi-nodular uptake pattern in 5, diffuse irregular thickened uptake pattern in 2, some focal thickened pattern in one, and a slight diffuse uptake pattern in one. Two of the 3 patients diagnosed as N0 by PET and operated on had negative lymph nodes confirmed pathologically. The other patient diagnosed as N0 by PET, who had one month of time lag between PET/CT examination and surgery, was confirmed as N2 by extrapleural pneumonectomy. In 3 patients, hilar or mediastinal lymph nodes were difficult to distinguish from irregular pleural thickening. One patient had a FDG positive lymph node in the ipsilateral supraclavicular region confirmed as metastasis (N3). One patient had a FDG positive lymph node in the para-aortic region. Lung metastasis was seen in one patient (M1). In another patient, two focal nodular uptakes in the colon were detected and confirmed as colon polyps (pathologically Group 3-4). At restaging, 3 of 4 patients showed diffuse+multi-nodular uptake and one patient showed multi-nodular uptake.

The utility of FDG-PET/CT is limited for evaluation of primary tumor extension and nodal status. FDG-PET/CT is useful for detecting distant metastasis and for evaluating activity in supraclavicular or abdominal lymph nodes. It is also useful for identifying unsuspected diseases.