1. Background: Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor with a complex growth pattern. Imaging plays a crucial role in diagnosis and management. The diagnosis of MPM is based on histology using essentially immunohistochemistry on pleural biopsies. Occasional long-term survival results are probably due to the biologic characteristics of the disease. 18F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)-computed tomography (CT) (FDG PET-CT) has become an invaluable tool for the diagnosis, staging, and prognosis of this severe disease as it combines both anatomic and functional information in a single imaging procedure, allowing for improved management of this disease. Coronal maximum intensity projection (MIP) ninety minutes postinjection of FDG demonstrating the encasing pattern of distribution in pleural mesothelioma with diaphragmatic extention. Conclusion: Methods: 18F-FDG-PET-CT imaging in malignant mesothelioma Nil Molinas Mandel1, Handan Tokmak2, Onur M. Demirkol2, Kerim Kaban2, Şükrü Dilege1 1Koç University, Istanbul/TURKEY, 2American Hospital, Istanbul/TURKEY Insert Footer or Copyright Information Here Figure 1: PET-CT also indicated metastasis in the lymph node in 4 patients (50%) and in the peritoneal lesions in one patient (12.5%) with MPM. The results showed that 18F-FDG PET-CT at delayed phase is very useful for the diagnosis of pleural diseases and high uptake of 18F-FDG PET-CT may be a predictive factor of prognosis in MPM patients. Figure 1: Pretreatment and posttreatment FDG PET images A B The main topics concern the use of ¹ ⁸ F-FDG- PET/CT in radiation therapy planning, monitoring of treatment (surgery/chemotherapy) response and prognosis assessment. MPM has a limited response to conventional chemotherapy and radiotherapy, thus early diagnosis of MPM is extremely critical. In these group patients, PET- CT showed all lesions with high sensitivity (%100). CT scans have limited accuracy in the differentiation between benign and malignant pleural disease. Also CT tends to underestimate early chest wall invasion and peritoneal involvement and has well-known limitations in the evaluation of lymph node metastases. Several studies have reported that 18- fluorodeoxyglucose (FDG) PET-CT plays an important role in the assessment of thoracic malignancy such as lung cancer. With a small patients experience, we suggest that PET-CT is useful as an aid for diagnosis and prognosis of MPM. PET-CT provides useful information concerning the extension of the lesions to thoracic and abdominal walls not fully evaluated by the initial conventional cross-sectional imaging. PET/CT also allows an accurate therapeutic monitoring of the disease. From April 20011 and May 2013, eight patients with histologically proven MPM underwent integrated 18FDG PET and computed tomography (CT) scanning. These were analyzed: mean age was 53.6 years (range: 40-66) and histologic MPM subtypes were epithelioid (7 patients) and biphasic (1 patients). We observed a significant correlation between high SUVmax and high-grade disease. There were 75 % male patients and 25% female patients. PET-CT images showed intense abnormal FDG uptake (SUVmax>8.0) in the pleural lesions of all 8 MPM patients at delayed phase, while it showed abnormal FDG uptake in all (100%) patients at early phase. In all patients, the values of SUVmax at delayed phase were higher than those at the early phase.. Our results showed (even with a limited group of patients experience), PET/CT seems to be superior to convantional imaging modalities in identifying more extensive disease involvement, and detecting unexpected occult distant metastases. 1.M, Gerbaudo VH, Gill RR, Jacobson FL, Sugarbaker DJ, Hatabu H. Morphologic and functional imaging of malignant pleural mesotheliomYamamuro Eur J Radiol. 2007 Dec;64(3):356-66 2.Kruse M, Sherry SJ, Paidpally V, Mercier G, SubramaniamFDG PET/CT in the management of primary pleural tumors and pleural metastases RM.AJR Am J Roentgenol. 2013 Aug;201(2):W215-26. References Figure 2: Figure 2: Pretreatment 18FDG PET-CT images