Gastric Carcinoma At High-field MRI: Diagnosis,Staging,and Correlation With Histological Of Pathology

ObjectivesTo evaluate the v alue of both MRI and fMRI at high-field in preoperative diagnosing,staging of gastric carcinoma, and to analyze the correlation of DCE-MRI with histologicalof gastric carcinoma.Materials and MethodsProspective study of47patients with gastric diseases and Another10cases of healthypeople were randomly selected to observe the situation of the stomach wall was conductedby using SIEMANS AVANTO1.5T MR scanner with a8-channel phased-array surfacecoil. All of the examinees were fasted and given20mg of anisodamine20min beforeexamination, with500-1000ml warm Water5min before examination.Routine MRI scanning: true fast imaging with steady-state precession (true-FISP)sequence；turbo spin-echo (T2WI/TSE) sequence plus respiratory gating；half Fourieracquisition single shot turbo spin echo（HASTE); fast low angle shot（FLASH）sequence；fast spoiled gradient-echo (FSPGR) dual in-phase/out-of-phase； The scan position is tothe axial, supplemented by the crown and sagittal.Diffusion-weighted imaging (DWI)：SE/EPI sequence was performed with b values（b=0and1000）. The apparent diffusion coefficient (ADC) of different gastric diseaseswere measured and compared.Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)：flash3Dsequence was used; The time-intensity curve (TIC) was obtained; The signal indensity ofpeak enhancement and time to peak enhancement under various degrees of gastriccarcinoma differentiation were measured; Correlation study of gastric carcinoma results ofimmunohistochemical (CD34) MVD and VEGF-2levels were also invested.Statistic method: SPSS13.0was used to analyze the parameters. Results:(1)The1-3layers of gastric wall were displayed with the moderate water-fillingmethod on vivo MRI. The rate of multi-layer structure in isolated gastric specimensincreased. The location, size and shape.of gastric carcinoma can be shown clearly andaccurately by multi-faceted of MRI scanning and3D reconstruction.(2)There is a significant difference in the sense of ADC values between benign/malignant tumors and gastric carcinoma of different degree of malignancy (F=26.76，p<0.05）；According to the ROC curve, ADC value<1.36x10-3mm2/s as a standard for thedetection of gastric cancer with sensitivity87.5%and specificity90%; There were alsostatistically significance of ADC value between metastatic lymph nodes and non-metastaticlymph nodes (t=2.18，p<0.05);(3)We observe two patterns of manifestation on dynamic contrast enhanced MRimagings: homogeneous enhancement (12cases) and irregularly enhancement(18cases).Setting the maximum diameter of tumor (4cm) as the dividing line, the two patterns hasstatistical significance（P=0.008，P<0.05）. In addition, there is a strong positive correlationbetween the signal of peak enhancement (Y) and MVD （x）（r=0.70，p<0.05）. The linearregression equation Y=69.51+4.07x was also obtained. We also observe that there was astrong negative correlation between time to peak enhancement and MVD(X)（r=-0.81，p<0.05）. What’s more, the signal of peak enhancement of VEGF positive group wassignificantly higher than that of VEGF negative group（t=3.6029，p<0.05）; Moreover, thereis a significant differences among MVD (/HPF), VEGF-2positive rate, TIC of Ⅰ type andTIC of other various types (t=3.82,p<0.05).(4)The total accuracy of MRI for T stage and N stage of gastric cancer were73.17%and71.05%respectively. The control was performed with Gastric cancer MR staging andpathological staging of surgery, with a satisfactory consistency according to theconsistency test.Conclusions(1)There is a strong correlation between the display ability of stomach wall layers andthe stomach cavity filling.(2)MRI has the ability to accurately display the location, size and the shape of tumor.If combined with functional imaging, MRI can also provide us a preliminary judgment ofthe occurrence of benign/malignant tumors together with the degree of malignancy ofgastric carcinoma. (3)DWI has a high sensitivity and specificity in detecting both advanced gastriccarcinoma and lymph nodes. While ADC is a useful tool for the diagnosis and differentialdiagnosis of gastric carcinoma, it is susceptible to respiratory motion and media, thusresulting in artifacts and the decrease of spatial resolution. In addition, ADC has a lowerdetection rate for early gastric cancer lesions and small lymph nodes.(4)DCE-MRI can reflect local microcirculation information of gastric carcinoma.More specifically the type of TIC and time to peak can reflect the level of MVD, VEGF-2,providing a new method for showing non-invasive gastric microcirculation characteristics.(5)MRI and DCE-MRI has certain advantages for TNM-staging of gastric carcinoma,especially T4-staging and M-staging.