Clinical Application Research Of Dual Source CT Perfusion Imaging In Evaluating The Tumor Angiogenesis And Biological Behavior Of Gastric Carcinoma

IntroductionThe incidence of gastric cancer is the highest among the malignant tumors and about 160,000 patients die of the disease in China every year.Thus,many researchers have been focused on the study of the diagnosis,treatment and biological behavior of gastric carcinoma.Besides,before performing the radical cure operation of subtotal gastrectomy,whether to estimate the differentiation degree of tumor cells,the invasive depth in the gastric wall and the metastasis of the lymph node correctly and objectively will exhibit great significance.Although the general imaging methods have the active role in this aspect,they are limited to some extent.Tumor angiogenesis is closely related to the growth,invasion,metastasis and prognosis of tumor,and nowadays it is the hot point in basic medical research.The indexVEGF is an important one reflecting tumor angiogenesis and MVD is also the gold standard in assessing tumor angiogenesis,but because the determination of MVD requires pathological tissues and due to the complicated peformation and having some injures,it is difficult to apply widely in clinical practice.So a kind of determining methods which is noninvasive,convenient and rapid of tumor angiogenesis have been desperately needed to evaluate the biological behavior objectively and scientifically. Perfusion is defined as the process in which the oxygen and nutrients carried by the capillary network are transported to the tissues and cells in the body,to a certain extent, it can reflect the hemodynamics and the functions of tissues and organs.And CT Perfusion Imaging is referred to the method by which we can show the perfusing course of the patients visually and analyze it quantitatively.Specifically speaking,we can perform the dynamic scanning for selected level while using contrast injection in order to obtain time-density/signal curve within the level,then it can demonstrate the concentration changes of the contrast injection in the determined organ,furthermore having a reflection of the change of perfusion amount in the body indirectly.Thus,CT Perfusion Imaging is increasingly emphasized in the imaging research of the ontology due to having the potential of estimating tumor angiogenesis and biological behavior more reasonably.The tumor angiogenesis is capable of inducing the changes of blood vloume, perfusion amount and capillary permeability,fortunately,CT Perfusion Imaging can reflect the alterations very well and this has a wide application prospect in the quantitative and qualitative research of ontology.So far,the reports on the perfusion imaging is very rare and it is on the starting stage,so its application value requires studying in a further way.And it is essential to carry out a series of reseach work.The study of the relationship between the parameters of perfusion in gastric cancer and tumor angiogenesis and the biological behavior is in the range.Materials and Methods1.Clinical datas and cases for groupThe number of patients with gastric adenocarcinoma in the first affiliated hospital of China Medical University was 69 cases.Among them,there were 49 cases for men and 20 for women and their age range was between 41 and 79,average at 58.The cases were divided into four groups according to the extent of cell differentiation of tumor after operation,that was 24 for low differentiation group,13 for low and median,12 for median and 6 for median and high group;there are also three groups on the basis of invasive depths in the gastric wall,namely,26 for myometrial invasion group,16 serosa infiltration and 13 tunica serosa;besides,the group for local lymph node metastasis and none were seperated based on whether having local lymph node metastasis or not,they were 29 and 26 cases respectively;furthermore,there were 14 for distant metastasis group,8 recent distant metastasis and 47 none distant metastasis according to whether generating distant metastasis and recent distant metastasis after operation or not.2.Examination methodThe patients were asked to drink 1000 ml water and to give an intramuscular injection of 20 mg anisodamine befor checking.Taking the breath exercise before scanning and no respiration transiently while scanning.Furthermore,firstly giving a ritual CT Horizontal Scan in order to determine the target layer and then the 50ml contrast injection(omnipaque) was through elbow vein with the injecting speed of 6ml per second,after that,the equivalent saline with the same injecting speed was followed, and at the beginning of 10 seconds,the patients were given the perfusing scan using the Siemens Dual Source CT Body Perfusion Scan for 40 seconds and the range was 28.8 mm.3.Photo Procession and AnalysisThe pictures were transferred to Simens Imaging Workstation to make an analysis. And the parameters such as Blood Volume,Blood Flow,Peak Time,Beginning Time of Perfusion and the corresponding function chart were obtained by maximum slope method.Besides,we could acquire the photo of Patlak vescular permeability and Patlak blood volume as well as the specified parameters through the perfusion model of Patlak tumor.The diameter of ROL was controlled within 1 cm and the position that influenced the accuracy of determination and be recognized by naked eye such as vascular imaging,the area of liquefaction and necrosis and pseudo shadow zone could be avoided.4.Samples Acquirements,Procession and Immunohistochemical StainingThe samples of Radical Gastric Large Partial Cystectomy were obtained and were maked paraffin section,then the tissue sections were stained immunohistochemically using CD34 monoclonal antibody of mice ressistance to human.The perfusion area of tumor was chosen from the operation samples,while drawing materials of the tissue in gastric mucosa were decided in the gastric mucosa beside carcinoma tissue larger than 4cm distant to the edge of cancer focus and non tumor tissue proved pathologically. What is more,all the materials were fixed with 10%formaldehyde and paraffin-embedded.And 5 pieces of continuous sections with 4um thick were got among which one was given the ritual HE staining and another four were stained immunohistochemically with CD34 and VEGF monoclonal antibody.Besides,the known section was considered as the positive control and 0.01mol/L PBS instead of first antibody as the negative control. 5.Results DeterminationHotspot method was applied to determine MVD value:firstly,the slices were put under the vision of 10x10 fold Optical Microscope to make sure the highest vascular density area in tumor that was stained brown by CD34,and then with 20x10 fold Optical Microscope,we chose three highest vascular density area to count,calculate the average value as the MVD value of the patient.No matter the single cell or cell mass which was stained by the antibody formed the lumen or not,it was considered as the countable microvessel if it had the clear septation with the microvessel,tumor cell and other connecting tissue elements.The hardened zone inside the tumor and the microvessel inside the soft tissue of the tumor juncture were not counted,as well as the thick smooth muscle wall and the vessel of the lumen diameter larger than 8 erythrocytes.The judging standard and procedure of the VEGF were as follows:in the first place,Grading the staining density:0 as colorless,1 light yellow,2 yellow brown, 3 chocolate brown.And then,we ranked the percentage of positive cells:no positive cell as 0 score,lower than 25%was 1 score,between 25%and 50%counted as 2 score and the percentage of positive cells larger than 50%as 3 score.And the staining density per slice multiplied by the percentage of the positive cells as the final score,the result of immunicalhistochemistry is positive while the multiplying value wa≥3,furthermore, the strong positivity was shown as the value was≥6.)6.Statistical AnalysisSPSS13.0 Statistical Software was used to have processed statistically and P＜0.05 as the standard of having the significant difference.Results1.VEGF and MVD Count expressed in gastric cancer tissue were significantly higher than in the normal gastric mucosa tissue adjacent to carcinoma,(P＜0.05) And the expression of VEGF in the gastric cancer tissue had a positive relation to the MVD Count(r=0.728).2.The Dual Source CT perfusion parameters of gastric cancer PBV,Patlak P,BF and BV value was positively related to the rating value of VEGF expression and MVD Count.3.There was a significant difference for VEGF expression of gastric cancer tissue and MVD Count among different invasive depths groups in the gastric wall,lymph node metastasis groups,none lymph node metastasis groups,recent distant metastasis and none distant metastasis,that is,with the higher invasive depths groups in the gastric wall,the appearance of lymph node and recent distant metastasis,the VEGF expression was enhanced and MVD Count increased,but there was not significant difference in different tissues of different differentiation degrees for the VEGF expression and MVD Count.4.The BF value in the distant metastasis and in the recent distant metastasis as well as the recent distant metastasis group were higher than none distant metastasis, meanwhile the evident difference was oberved,P＜0.05(F=6.555,5.972).BV value in the muscularis infiltration group and the serosa infiltration group were significantly smaller than the serosa external group,P＜0.05(F=5.460).Besides,the value of Patlak P in the muscularis infiltration group was lower than in the the serosa external group and it had the significant difference,P＜0.05.And we concluded that PBV value was negatively correlated to the cell differentiation degree,besides,positive correlation was observed between BV,BF,Patlak P,PBV value and invasive depths and the extent of distant metastasis.Besides,there existed the positive relationship between BV,BF,Patlak P value and distant metastasis.Similarly,Patlak P value were positived related to the degree of lymph node metastasis.Conclusion1.Tumor angiogenesis exsited in the gastric cancer tissue,where the VEGF played an important role,and it had a close relationship with invasive depths in the gastric wall, lymph node metastasis,distant metastasis and biological behaviors which could be well reflected by MVD Count and the expression of VEGF.2.The Dual Source CT Perfusion Imaging parameters Patlak P,BF,BV,PBV was able to demostrate tumor angiogenesis and biological behaviors of tumor.Among them, BF and BV value could evaluate whether to generate distant metastasis and recent distant metastasis after operation or not objectively.Similarly,BV and PBV value was capable of estimating the depth of whether the cancer tissue could get through gastric wall objectively.PBV was an index that could reflect the degree of cell differentiation in gastric cancer.Also Patlak P value was able to have a reflection of lymph node metastasis.Besides,BV,BF,Patlak P and PBV could show the invasive depths in the gastric wall.Furthermore,BV,BF,Patlak P could reflect the distant metastasis to some extent.