| Objective1 To find optimal parameters those can sensitively and specificly diagnose gastric cancer and determine the best diagnostic threshold for gastric carcinoma.2 To compare the application value of the ADCslow and normal ADC value.3 To find optimal parameters those can sensitively and specifically distinguish different pathological types,grade and determine the best diagnostic threshold for each parameters.4 To find a medical imaging marker that can evaluate the curative effect of anti-angiogenesis therapy and individualized treatment prognostic by analyzing the correlation between gastric cancer prognostic factor（vascular endothelial growth factor and microvessel density）and biexponential multiple b-value DWI.Materials and Methods1 A total of 89 gastric carcinoma patients who meet the inclusion criteria and confirmed by surgical pathology were conducted as the study group（A group）.And 30healthy volunteers randomly selected who has the similar age and sexy were conducted as the control group（B group）.Gastric carcinoma patients were divided into intestinal type（C group,64）and diffuse type group（D group,25）by Lauren standard.Gastric carcinoma patients were divided into low grade malignant group（E group,59）and high grade malignant group（F group,30）using WHO differentiation level.2 The pathological specimens of gastric surgery were observed in addition to the conventional HE staining but also the immunohistochemical staining using rabbit anti human CD34 monoclonal antibody and rabbit anti human VEGF monoclonal antibody to observe the MVD and VEGF.3 The patients were scanned using SIEMENS AVANTO 1.5T MR scanner（Siemens Healthcare,Erlangen,Germany）with a 8-channel phased-array surface coil.T2WI,T1WI,biexponential multiple b-value DWI axial,coronal/sagittal T2WI,oblique T2WI in disease area were performed during the scanning.4 Two readers respectively measured the different b-value DWI imagings of gastric carcinoma and normal gastric by using the SIMENS MRI workstation（MMWP VE4.0,Siemens Healthcare,Erlangen,Germany）.The ADCfast,ADCslow,Ffast and ADCstandard were calculated by a third-party software.5 All statistical analyses were performed by using SPSS 20.0 and Medcalc.We firstly used the Bland-Altman plot to measure the consistency and reproducibility of the ADCfast,ADCslow,Ffast,ADCstandard measured by the two readers and calculate the intraclass correlation coefficient.The normality and homoscedasticity of ADCfast,ADCslow,Ffast,ADCstandard were tested by using the Kolmogorov-Smirnov test and Levene’s tests for each group.Data not satisfying the assumption were analyzed by using the Mann-WhitneyUtest.Datasatisfyingthe assumptionweresubjectedto independent-sample t test.P values of less than 0.05 determined statistical significance.The ability to discriminate gastric cancer and normal gastric,discriminate different pathological types,discriminate different pathological grade was analyzed by using receiver operating characteristic curve（ROC）regression model,and quantified by sing the areas under the ROC curves（Az）,The diagnostic sensitivity,specificity were calculated at a point that maximized the value of the Az.The correlations between the ADCslow,ADCfast,Ffast,ADCstandard and gastric cancer prognostic factor（VEGF and MVD）were assessed with Spearan correlation and drow a Box plot picture.Results1 The ICC Values in gastric cancer group of the ADCslow,ADCfast,Ffast,ADCstandard measured by the two readers were 0.914,0.904,0.882,0.822.The ICC Values in healthy group of the ADCslow,ADCfast,Ffast,ADCstandard measured by the two readers were 0.956,0.917,0.844,0.819.The ICC Values and Bland-Altman plot show that the data measured by the two readers has a good consistency.2 The gastric cancer tissue had significantly lower ADCslow,ADCfast,ADCstandard value than that in normal gastric tissue.The Ffast value in the gastric cancer tissue were higher than that in the normal gastric tissue significantly.3 The ADCslow calculated by the biexponential method was lower than the ADC(ADCstandard)calculated by the traditional method in gastric cancer and normal gastric.4 The difference among ADCslow and the rest is significant in diagnosing gastric cancer and normal gastric.The difference among ADCfast,Ffast,ADCstandard had no statistical significance.5 The diffuse type gastric cancer had significantly lower ADCslow value than that in the intestinal type gastric cancer.The diffuse type gastric cancer had significantly higher Ffast value than that in the intestinal type gastric cancer.The ADCfast,ADCstandard value in the diffuse type gastric cancer were lower than that in the intestinal type gastric cancer,but the difference had no statistical significance.6 The difference between ADCslow and Ffast is significant in diagnosing different type of gastric cancer.7 The high grade malignant gastric cancer had significantly lower ADCslow,ADCfast,ADCstandard value than those in low grade malignant gastric cancer.The high grade malignant gastric cancer had significantly higher Ffast value than that in low grade malignant gastric cancer.8 The difference between Ffast and ADCstandard is significant in diagnosing different grade of gastric cancer.The difference among the else had no statistical significance.9 The ADCslow,ADCfast,Ffast,ADCstandard had a correlation with VEGF（Spearman coefficient were-0.796,-0.252,0.915,-0.561）.The ADCslow,ADCfast,Ffast,ADCstandard had a correlation with MVD（Spearman coefficient were-0.756,-0.216,0.867,-0.552）.Conclusion1 The ADCslow is a reliable imaging target for diagnosing gastric cancer,the best diagnostic threshold is 0.901×10-3mm2/s.2 The ADCslow calculated from biexponential multiple b-value DWI can reflect the water molecular diffusion state better than ADC(ADCstandard).3 The ADCslow is a reliable imaging target for diagnosing different pathological type of gastric cancer,the best diagnostic threshold is 0.395×10-3mm2/s.The Ffast and ADCslow are reliable imaging target for diagnosing different pathological grade malignant of gastric cancer,the best diagnostic threshold are 0.369,0.484×10-3 mm2/s respectively.4 The Ffast had a high positive correlation with VEGF and MVD of gastric cancer,the ADCslow had a high negetive correlation with VEGF and MVD of gastric cancer.The Ffast and ADCslow have the potential to assess the clinical prognosis and the anti-angiogenesis efficiency. |
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