A Prelimilary Study On MSCT Perfusion Imaging And It's Correlation With Angiogenesis In Gastric Tumor

Objective(1) To study the application of 64-slice CT Perfusion Imaging(CTPI) technique in stomach carcinoma,make a comparison of the CTPI Parameters in different pathologic types of gastric tumor,and analyze the relativity between CT perfusion parameters and some factors affecting the prognosis of stomach carcinoma(differentiation degree, infiltration depth,TNM staging and lymph node metastasis).(2) By detecting microvessel density(MVD) in gastric cancer,gastric lymphoma and gastric interstitialoma,and VEGF in gastric cancer,respectively,the correlation between MVD,vascular endothelial growth factor(VEGF) and preoperative multi-slice spiral CT (MSCT) perfusion parameters were analyzed to explore the value of MSCT Perfusion Imaging in evaluating angiogenesis of gastric tumor.Materials and methods(1) Thirty-seven patients diagnosed as gastric tumor by the gastroscopy and postoperative biopsy underwent 64 MSCT perfusion imaging scanning.They were classified into three groups according to the pathological findings:gastric cancer group (n=24),gastric lymphoma group(n=4) and gastric interstitialoma group(n=7).The CT hemodynamic parameters in regions of interest(ROI) including blood flow(BF),blood volume(BV),mean transit time(MTT) and permeability surface(PS) were measured and statistically analyzed.The relationship between CT perfusion parameters and some factors affecting the prognosis of gastric carcinoma(differentiation degree,infiltration depth,TNM Staging and lymph node metastasis).Notability verification was performed.(2) CD34 immunohistochemical staining was performed in tissue sections from 23 cases of gastric cancer and 4 cases of gastric interstitialoma,CD31 immunohistochemical staining in 7 cases of gastric interstitialoma,and VEGF immunohistochemical staining in 23 cases of gastric cancer.The correlation between MVD,VEGF expression and clinical pathological characteristics were also analyzed;The parameters of MSCT perfusion imaging including BV,BF,MTT and PS were correlatively studied with MVD,VEGF expression in gastric cancer group,and with MVD in gastric lymphoma group and gastric interstitialoma group.Results(1) Among all 37 cases of gastric cancer,35 patients underwent the CTPI successfully. The image of targeted slices was good,with continuous TDC of tumor ROI and slight wave motion.The image had artifacts in two cases because the pationts can't control his breath well.(2) The mean BF,BV,MTT and PS were65.42±28.19ml/min.100g,6.13±2.49ml/100g, 9.35±5.41s and40.39±23.59ml/min.100g in gastric cancer group;23.60±14.87ml/100g.min, 2.64±0.58ml/100g,10.68±5.33s and 22.51±15.99ml/100g.min in gastric lymphoma group; 50.66±30.92 ml/100g,min,4.95±1.61ml/ 100g,11.23±8.09s,10.05±8.96 ml/100g,min in gastric interstitialoma group,respectively.The mean BF,BV and PS between gastric cancer group and gastric lymphoma group,the mean PS between gastric cancer group and gastric interstitialoma group,the mean BV between gastric lymphoma and gastric interstitialoma groups had significant difference(P＜0.01).There were significantly statistical differences in mean BF and PS between gastric lymphoma group and gastric interstitialoma group (P＜0.05).No significant statistical differences were found in mean BF between gastric cancer and gastric interstitialoma and the mean MTT among the three groups(P＞0.05).(3) Compared with gastric carcinoma group,the time-density curve(TDC) of gastric lymphoma(GL) group went genlte and smooth and the CT value(reflected by Y-axis of curve) was lower.The TDC of gastric interstitialoma group had cross-over with those in gastric lymphoma group and gastric carcinoma group.The CT value in TDC of 4 cases of gastric lymphoma rose to 50-55 HU within 10-30 seconds and remained in platform stage until the scanning was terminated.The CT value in TDC of 23 cases of gastric carcinoma was elevated to 80-120 HU within 12-35 seconds and remained in platform stage until the scanning was terminated.The CT value in TDC of 7 patients with gastric interstitialoma rose to 45-100 HU within 10-30 seconds and remained in platform stage the scanning was terminated.The BF and BV map of gastric lymphoma showed a little red and yellow zone on blue background;The BF and BV map of gastric interstitialoma showed slightly less or more red and yellow zone on blue background.In the BF and BV map of gastric carcinoma, red and yellow pseudo color was different according to the differentiation degree and active part in the mass,but the red and yellow zone was larger than that of gastric lymphoma or gastric interstitialoma with less blood supply.The red pseudo color in PS map of gastric carcinoma and gastric lymphoma was deeper than that of gastric interstitialoma,which indicated high permeability.(4) In gastric cancer group,there was no significant correlation between the CT perfusion parameters(including BF,BV,MTT,PS) and differentiation degree,infiltration depth,TNM staging and lymph node metastasis(P＞0.05).The PS value was significantly related to differentiation degree,TNM staging and lymph node metastasis(P＜0.05),but no correlation with ectoptygm infiltration was noted.(5) The mean MVD in gastric cancer group,gastric lymphoma group and gastric interstitialoma group were 38.65±12.21,37.5±11.82 and 22.86±10.84,respectively.There was significantly statistical difference between gastric cancer group and gastric interstitialoma group(P＜0.05),and no significant difference between gastric lymphoma group and gastric cancer group or gastric interstitialoma group(P＞0.05).(6) There was no obvious relativity between the CT perfusion parameters(including BF,BV,MTT,PS) and MVD in gastric cancer group,gastric lymphoma group and gastric interstitialoma group(P＞0.01).There was no obvious correlation between the BF,BV,MTT,PS and VEGF expression in gastric cancer group(P＞0.05).(7) There was no remarkable correlation between MVD,VEGF positive expression and TNM staging,lymph node metastasis in gastric cancer group,but the correlation between MVD value,VEGF positive expression and tumor stage,ectoptygma infiltration was significant(P＜0.05).Conclusions(1) MSCT perfusion imaging could provide hemodynamic quantitative information in the treatment of gastric tumor.There are significantly statistical differences of MSCT perfusion imaging parameters between gastric cancer,gastric lymphoma and gastric interstitialoma,which is useful in differential diagnosis.(2) The PS value of gastric cancer is helpful to detect the differentiation degree,TNM staging and lymph node metastasis of tumor and provides reference to preoperative evaluation and combined therapy.(3) The MVD in tumor tissue is positively correlated with VEGF expression level,i.e. the bigger MVD,the higher VEGF positive expression.(4) There is no obvious correlation between the CT perfusion parameters(including BF,BV,MTT,PS) and MVD in gastric cancer,gastric lymphoma and gastric interstitialoma(P＞0.01),and no significant correlation between CT perfusion parameters and VEGF expression in gastric cancer(P＞0.05).(5) As a new functional imaging technique,MSCT perfusion imaging(MSCTPI) makes up the disadvantages of traditional morphological imaging and is feasible in the study of gastric tumor,however,the scanning and image postprocessing still need further improvement.