Study On The Correlation Among SCT Features, Tumor Angiogenesis And The Expression Of NM23-H₁ In Colorectal Carcinoma

Background and purpose: Colorectal carcinoma is very common malignant tumors in gastrointestinal tract. With the using of Spiral CT (SCT), the accuracy of clinic diagnosis and preoperative staging in colorectal carcinoma has been improved rapidly. So, SCT is considered as an effective method in examination of the colorectal carcinoma. Imaging features of all tumors are based on their pathological natures and determined by their biological behaviors. Recent reports reveal that tumor angiogenesis is necessary for growth and metastasis in all-solid tumors. Microvessel density (MVD) in tumor is one of the most important factors that influence tumor's biological behaviors. Tumor angiogenesis is regulated by many kinds of correlative factors. Vascular endothelial growth factor (VEGF) is considered as a potent angiogenesis-promoting factor that relate to tumor angiogenesis, infiltration, metastasis and prognosis. Nm23-H1 (non-metastasis 23- H1) has been proved to be an inhibiting factor of metastases in certain human tumors, especially in hepatic metastasis that is from large intestine. The inherent relationship between modern medical imaging and molecular biology can be found by comparing SCT features of tumor with its biological behaviors. The purpose ofthis study is to evaluate the correlation among SCT features, MVD and the expressions of VEGF and nm23-H1 in colorectal carcinoma.Materials and methods: Water enema spiral CT, including plain scan and biphasic dynamic contrast-enhanced scan, were performed in 42 patients with colorectal carcinoma before operation. Laxative was given to patients the day before examination. About 15 minute before the scanning, 10 mg 654-2 was injected intramuscularly. Then a Foleys tube was inserted into the rectum of patient to enema the lukewarm water. On average, 1.5-2L of water was administered. Spiral CT examination was performed with a GE HiSpeed Advantage Rp22 Helical scanner. The plain scan was taken at the first time. The scanning parameter of SCT were 120kv, 280mAs, collimation 7mm, pitch 1:1, scanning time 7-20s, held breathing for 1 time. Then the contrast-enhanced (CE) scan was performed when the primary tumor was defined. The CE scan included arterial and venous phases. About 100ml contrast medium was injected into the elbow vein of patient with the speed of 2.5-3ml/s. The contrast medium was Omnipaque or Ultravist (300mgl/ml). In the arterial phase of the CE scan, only the region of the primary tumor was covered. The whole abdomen and pelvis was examined in the venous phase of the CE scan. The patient held breathing for 2 times during the CE examination. All 42 patients underwent coloproctectomy within a week after SCT scanning. After operation, all the specimens were fixed in 10% neutral formalin and embedded in paraffin. Immunohistochemical streptavidin peroxidase conjugate method was used to analyze the MVD as well as the expressions of VEGF and nm23-Hi in colorectal carcinoma. Statistical analysis was performed with SPSS 10.0 software, using t-test, ANOVA and Chi-square test. Statistically significant level was considered as "alpha equals 0.05".Results: 1. Using two-phase enhanced SCT scans, the accuracy of staging of TNM and Dukes in 42 patients were 83.3% and 90.5%, respectively.2. In 42 cases, VEGF and nm23-H1 expression were detected in 23 and 18 patients. The VEGF and nm23-H1 positive rates were 54.76% (23 of 42) and 42.86%(18 of 42) respectively. Microvessel densities ranged from 14.33 to33.33 with a mean of 23.83(standard deviation, 4.69). The VEGF-positive rates were 75.00%(12 of 16) and 42.31%(11 of 26) respectively and the nm23-H, -positive rates were 12.50%(2 of 16) and 61.54%(16 of 26) respectively in the group with lymph node metastases and the group without lymph node metastases of 42 cases in SCT features, the difference of the VEGF-positive rates between two groups was statistically significant as same as the nm23-Hi -positive rates(x2=4.273, F=0.039 and x2=9-726, P=0.002, respectively). In the two groups, the microvessel den...