| Gastric malignancy tumor is the second most frequent cause of cancer related death worldwide. Positron Emission Tomography (PET) with 2-deoxy-2 [18F] fluoro-D-glucose (18FDG), a structural analog of glucose, allows tumor images to be obtained, based on increased glycolysis in malignancy cells. The high sensitivity and high specificity of 18FDG PET in most malignant tumors may enable this technique to play an greater role in tumor diagnosis. In spite of that, only a few 18FDG PET studies have been reported on gastric malignancy tumor presently. In this paper, we tried to evaluate the clinical significance of PET in preoperative staging and diagnosis of gastric malignancy tumor. We also designed a study to investigate the expression of facilitate glucose transporter 1 (Glutl) and its relationship with uptake of 18fluoro-2-deoxyglucose (18F-FDG) in gastricmalignancy tumor,objective: Preoperative staging with 18F-FDG PET and staging during exploratory laparotomy were performed by experienced surgeon in patients with gastric malignancy. The results were compared with the postoperative pathological results respectively. The original PET diagnosis was related to histological findings to determine sensitivity and specificity. A retrospective analysis was performed to investigate the relationship between quantitative parameters as determined by PET imaging and clinicopathologic findings of gastric malignancy tumor. At the same time, we also evaluate the diagnostic accuracy and clinical significance of PET compared with that of computed tomography (CT) and magnetic resonance imaging (MRI).Method: 32 patients suspected gastric malignancy tumor underwent 18F-FDG PET scan, and CT was additionally performed in 17 patients. 18F-FDG was synthesized using a standard technique in an automated synthesis unit. FDG was injected intravenous as a bolus. Scanning was performed 50-60 min later using a Simens Ecat HR plus PET scanner, which is capable of imaging a 15cm field of view. When the PET was scanning field of stomach, 3.0g-6.0g vesicant was taken orally by patients. PET data was analyzed semi quantitatively by calculating standard uptake value (SUV), tumor liver ratio (TLR), tumor to non-tumor ratio (T/NT) andalso by a visual method. PET Imagings were first interpreted by inspection. Primarily, FDG uptake values were calculated regions of interest, which were at least 13 pixels in size, and the patients' weight in the denominator. This study was also to characterize the FDG uptake of gastric malignancy tumor by relating it to the histopathological properties of the tumors. The same doctor performed staging during exploratory laparotomy. Lymph nodes and metastasis detected by preoperative PET scan were explored especially and checked by the same pathologist.Immunohistochemistry with Glutl polyclonal antibody was performed to elucidated the extent of its expression and distribution pattern on 33 gastric malignancy tumors and normal gastric tissues. Glutl-positive and Glutl-negative malignancy tumor were analyzed for their clinicopathologic characteristics including histological subtype, lymph node metastasis, and size. The intensity of Glutl in 23 tumor which were evaluated with PET scan was assessed by computer image analysis. Correlation analysis was carried out between expression of Glutl and the uptake of 18F-FDG.Results: There are 25 malignant tumors and 7 benign diseases in all 32 patients. When the visual method was used, the sensitivity and accuracy was 92%(23/25) and 87.5%(28/32) respectively. When using a mean standard uptake value with a cut-off of 2.5, the sensitivity andaccuracy was 84% (21/25) and 81.3%(26/32) respectively, and the rate of false positive and false negative was 28.6%(2/7) and 16%(4/25) respectively. The different cut-off of semiquantitative parametes affected diagnostic ability of PET significantly. If 100% sensitivity is the goal, the cut-off for maximum standard uptake value has to be 1.5 or less. If using the mean standard uptake value at a 3.0 cut-off as a... |
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