| Objective:Ascites is one of the most comman diseases,its differential diagnosis of benign and malignant is a key role to establish treatment strategies and prognosis.At present,Cytology and clinical conventional imaging skills have certain value,but can not solve this difficult problem in clinic. But 18F-FDG PET/CT imaging has shown a larger advantage in knowing the whole body physical condition,and found the primary to ascites, indirectly responsible for the property of ascites. So the aim of this study was to evaluate the diagnostic value of 18F-FDG PET/CT for the patients with ascites of unknown causes.Materials and Methods:Fifty patients with ascites of unknown causes refered to our department for whole-body 18F-FDG PET/CT were retrospectively reviewed.The causes of their ascites could not be confirmed by laboratory examinations and clinical conventional imaging skills.Data of PET scan were reconstructed and fused with CT slices.PET,CT and fusion images were displayed in three orthogonal projections. Images were interpreted on the Xeleris workstation and all of the PET images were reviewed visually and semi-quantitatively. PET images were reviewed in conjunction with relevant the CT and the fused images used to identify malignant and benign lesions.The maximum standard uptake value (SUVmax) and the maximum diameter (Tmax) of peritoneum were measured,their differences of SUVmax and Tmax between benign lesions diseases and malignant diseases were also compared.SPSS17.0 statistical package was used to analyze in this study. P<0.05 was considered statistically significant.Results:①27 out of 31 patients with ascites caused by malignant diseases were correctly diagnosed.31 patients including 9 peritoneal cancer,7 ovarian cancer,2 hepatocelluar carcinoma,1 hepatic carcinoma with lung cancer,1 lung cancer,3 gastric cancer,4 pancreatic cancer,1 gallbladder carcinoma,1 colon cancer,and 1 ovarian cancer combined peritoneal cancer, and 1 Krukenberg tumor;16 out of 19 patients with benign diseases were correctly diagnosed.The causes of these 19 ascites patients consist of 3 liver disease,2 cardiac disease,2 kidney disease,1 hypoproteinemia,4 tuberculous peritonitis,2 autoimmune diseases,1 chronic peritonitis,4 ascites of unknown origin.3 false negative cases were 1 colon cancer with abdominal metastases,2 peritoneal cancer;2 false positive cases were 1 renal insufficiency and 1 tubereculous peritonitis;2 cases were regarded as malignant but failed in finding primary by PET/CT,one is ovarian cancer combined peritoneal cancer,another is peritoneal cancer.The accuracy of 18F-FDG PET/CT were 90.0%.PET/CT found 15 lymph node metastasis,2 bone metastasis,1 lung metastasis,1 pleural metastasis besides Peritoneal metastases.12 of lymph nodes metastases were abdomen and pelvic nodes,the rest of lymph nodes located in internal mammary (1), bilateral hilar (1), mediastinal(1). Pathological specimens were obtained from all these lymph nodes.②Tmax and SUVmax in benign ascites patients were 1.09±0.96cm,3.44±3.59 respectively;and 3.07±2.04cm,6.89±3.63 in malignant ascites patients.A bigger SUVmax (t=-3.300,P=0.002;) and Tmax (t=-4.605,P=0.000) was observed in malignant ascites patients.③According to Wilcoxon signed rank test,the survival difference of positive result and negative result was significant (Z=-15.848,P=0.000 bilateral),a longer survival was observed in those patients whose SUVmax smaller than 3.0(t=-3.573,P=0.001).SUVmax>3.0 or<3.0 (t=-3.513,P=0.001),Tmax>3.0cm or <3.0cm (t=-1.620,P=0.116),age>60 year or<60 year (t=-0.561,P=0.577), male or female(t=-0.146,P=0.884) did not show statistically signigicance.Conclusions:Firstly,18F-FDG PET/CT has useful clinical diagnostic value in finding primary of ascites.It can depict size,region,and make a primary level diagnosis of ascites property to instruct physician making treatment protocols.Secondly,because PET/CT can give the whole body condition of tumor distribution,in some unknown primary cases,the metastases in abdomain and in pelvic or Peritoneal metastases were contribute to diagnosis. It was helpful to differential diagnosis.Thirdly,18F-FDG PET/CT also has something not all were desired, false positive and false negative can not avoid,one of the most reason of false positive is tuberculous peritonitis which should be pay more attention to reduce the false positive cases. |
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