| Backgroud and purpose: Gastric stromal tumors (GST) are the most common mesenchymal neoplasms of the gastrointestinal tract. It is formed by the unconventionally multiplication of the tumor cells which have the various differentiation potential. In the past, it was usually diagnosed as Gastric leiomyoma or Gastric nervous tumor. But recently,It is reported by immunity histochemistry studies that the differentiation of these tumors can tend to smooth muscle, nerve, both smooth muscle and nerve, as well as lack of differentiation characters, but they do not typically originate from smooth muscle or nerve. The pathology and immunity histochemistry have made a great deal of correlational studies about the diagnosis, determination of benign or malignant, and prognosis of GST. Therefore, the imageology study of GST has been quite important. The objective of this research is to discuss the value of spiral CT in diagnosis, distinction diagnosis, therapy, and prognosis of GST.Materials and methods: 46 cases of gastric stromal tumor from January 1998 to March 2006 in our hospital were reviewed, Among them, there are totally 22 male and 24 female; all patients are from age 12 to 72, 31 patients are over 31 (66.3%) The main clinical symptoms are: abdominal pain(40.2%), abdominal mass(28.1%), and upper alimentary canal bleeding(43.1%), Non-special-symptoms are not infrequence yet(27.3%). All the patients were pathologically proved after surgical treatment (18 of them were misdiagnosed as other mensenchymal tumors of the GI tract and then were correctly diagnosed after All the immunohistochemistry examinations lately). Of the 43 single-occur GST, benign9 (boundary 5) , malignant 34. The 3 poly-occur GST are all diagnosed malignant by pathology. Investigations also include endoscopy, abdominal ultrasongraphy and X-ray barium meal. Patients received helical CT unenhanced and contrast-enhanced three-phase scans before surgical treatment. After plain CT scans, about 80-100ml contrast medium was injected by auto-injector at 3ml/s. Three-phase scans began at 25-30s(arterial phase), 60-70s(portal venous phase). The slice thickness was 10mm, pitch 1:1. If the tumors was small, the slice thickness should be 5.0mm. CT features with clinical and pathologic correlation were retrospectively studied and summarized with respect to surgery. Statistical analysis was performed with SPSS 10.0 software and statistically significant level was considered as "alpha-equals 0.05" .RESULT:①most cases are single. Of the 46 GST patients, single-occur 43, poly-occur 3.②GST commonly occur at the body and fundus of stomach. Of the 43 single GST patients, gastric body 24, gastric fundus 16, gastric antrum 3.③the 14 cases of the tumor size less than 5cm in diameter mostly appear round or ovoid shape: homogeneous density 10, non-homogeneous density 4; GST grow along the vertical plane of gastric wall, intra-luminal growth 7, extra-luminal growth 5, intra-extra-luminal growth 2.④the 29 cases of the tumor size larger than 5cm in diameter often appear irregular shape: Homogeneous density 2, non-homogeneous density 29, and usually accompany with bleeding, necrosis, mucous change; GST grow along the vertical plane of gastric wall, intra-extra-luminal growth 15, extra-luminal growth 9, intra-luminal growth 5.⑤enhancement appearance of SCT: Of the single 43 GST patients, according to parenchyma density: non-homogeneous enhancement 31, homogeneous enhancement 12; according to blood supply, obviously enhanced 40, non-obviously enhanced 3. special enhancement: septal enhancement, gradually ascending enhancement, obvious enhancement of arterial phase.⑥metastasis: hepatic metastasis 9, splenic metastasis 2; soft tissue metastasis around the incision of anterior abdominal wall and pleural metastasis 1; cavitas pelvis metastasis 2; CT findings of the 3 cases display lymphadenectasis, pathological results of chronic inflammation or Reactive hyperplasia have been confirmed. (7) the benign or malignant GST closely correlated with the CT features, such as the tumor size, shape and homogeneous or non-homogeneous enhancement (P<0.05), but not with growth pattern (P>0.05). the tumor size of GST closely correlated with the shape, growth pattern, necrosis and the non-homogeneous enhancement methods of the GST(P<0.05).Conclusion:①The CT image of GST are correlated with tumor size, the small ones(≤5cm) are often regularly shaped, homogeneous density; The larger ones (> 5cm) are often irregularly shaped, non-homogeneous density, and accompany with bleeding, necrosis, mucous change. (2) the tumor size larger than 10cm in diameter, non-homogeneous enhancement, intra-and extra-luminal growth and infiltrating its close organs hint the poor prognosis of GST.③GST commonly occur at the body and fundus of stomach (93%), less at gastric antrum.④GST scarcely metastasize to lymph nodes, but can metastasize through blood stream, and sometimes metastasize to regional organs by planting.⑤GST mostly grow along the vertical plane of gastric wall, size large but local.⑥GST may occur at several places at one time.⑦Spiral CT can precisely display the location, shape and size of gastric stromal tumors. It is very helpful to differentiate the bengin from the malignant tumors, and provide more useful information for early diagnosis and for the evaluation of the treatment and prognosis.
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