Kır, Kemal MetinFilik, Mustafa2022-08-082022-08-082012http://hdl.handle.net/20.500.12575/82925SUMMARYThe role of 18F- FDG PET/CT in the Primary Staging of Gastric CancerAimAim of this study is to investigate the role of 18F-FDG PET/CT in preoperative staging of gastric cancer, to compare with routinely utilized CT and to evaluate parameters to effect of 18F-FDG uptake.Material and Method31 patients (mean age: 58.9 ±12.6) who underwent 18F-FDG PET/CT in Ankara University Medical Faculty Department of Nuclear Medicine between June 2011 and June 2012 for primary staging of histopathologically proven gastric cancer were included to the study. 18F-FDG PET/CT findings were compared with histopathological results in patients who underwent surgery after PET/CT. Comparison was done in primary lesions, lymph nodes and adjacent organs. On the other hand, because they were accepted as inoperable according to findings of 18F-FDG PET/CT, CT and/or laparotomy/laparoscopy, 18F-FDG findings were not compared with histopathological results in 6 patients.ResultsAccording to postoperative histopathology reports, 14, 4, 4, 1, 1 and 1 patients were diagnosed as adenocarcinoma, signet ring cell carcinoma, adenocarcinoma with signet cell component, papillary adenocarcinoma, adenosquamous carcinoma and intestinal metaplasia without residual tumor, respectively. TNM stages of 1 (4%), 1 (4%), 4 (16%), 2 (8%), 12 (44%) and 5 (6%) patients were T0, Tis, T1, T2, T3 and T4, respectively. After histopathological examination of lymph nodes N staging of 8 (32%), 6 (24%), 6 (24%) and 5 (30%) patients was N0, N1, N2 and N3, respectively.18F-FDG PET/CT was normal in 2/31 patients. 18F-FDG uptake was seen in 12/31 patients in primary tumor, in 11/31 patients in perigastric lymph nodes and in 6/31 patients in distant organs. Postoperative histopathological examination results of 2 patients with normal 18F-FDG PET/CT were reported as multifocal intramucosal adenocarcinoma (Tis) and signet ring cell carcinoma. While mean SUVmax of FDG avid primary gastric lesions was calculated as 13.49± 9.29 (3.00?44.60), mean SUVmax of FDG avid lymph nodes was 29.10±7.36 (2.80?29.10). According to evaluation of histopathological subtypes, mean SUVmax of adenocarcinomas, signet ring cell carcinomas and adenocarcinomas with signet cell component were 15.16 (3.00?44.60), 9.90 (5.50?17.70) and 11.27 (6.20?13.90), respectively (p=0.721). In the comparison of preoperative abdomen CT with postoperative histopathology results, CT was TP in 23/25 patients, TN in 1/25 patient, FN in 1/25 patient in the detection of primary lesions. 18F-FDG PET/CT was TP in 20/25, FP in 1/25, FN in 4/25 patients, respectively. Although sensitivity, specificity, accuracy, PPV and NPV of CT in the detection of lymph node metastases were calculated as 83.3%, 75%, 80%, 87.5% and %66.6, respectively, these values were 64.75, 100%, 76%, 100% and 57.1% for 18F-FDG PET/CT.ConclusionWhile diagnostic power of 18F-FDG PET/CT in the preoperative staging of gastric cancer is lower than CT, but it is still comparable. 18F-FDG PET/CT could be beneficial in the evaluation of suspected lymph nodes because of its high PPV. The role of 18F-FDG PET/CT seems to be limited in preoperative staging of signet ring cell carcinomas which have lower FDG uptake than other histological subtypes and of early stage gastric cancer.Key words: Gastric cancer, preoperative staging, 18F-FDG PET/CT, lymph node metastasis.trmide kanseriprimer evreMedicalThesis