It is very significant that assessing staging in gastric cancer patients before surgery, furthermore, determining the optimize surgical strategy ,predict the the efficacy of neoadjuvant therapy for patients. For patients who are ineffective in neoadjuvant therapy, surgery will be more meaningful.

It has been reported that the application of CT(computed tomography,CT) and MR(magnetic resonance,MR) in staging of gastric cancer, but not in predicting clinical response to neoadjuvant therapy for gastric cancer. Only a few studies focused on T staging using conventional MRI in gastric cancer, however , relatively new sequences in the chest deserve widely used. To develop a pre-treatment evaluation methods for TN staging in patient with gastric cancer by utilization of the new imaging methods (T2-TSE-BLADE,T2 maps, StarVIBE, iShim-DWI and high resolution CT). By analysing the relationship between TN staging and imaging features to find the imaging characteristics for TN staging, and to find the indicators of new technology and reference values for facilitate pre-treatment diagnosis of TN staging, optimize surgical strategy , predict the the efficacy of adjunctive therapy , and OS and define the range of lymph node for radiotherapy , as making personal treatment planning for gastric cancer .

To explore the value of CT and MR using multiple sequences, including T2-TSE-BLADE, T2 maps StarVIBE, and iShim-DWI in evaluating the preoperative TN staging and prediction of response to neoadjuvant therapy and OS in patients with gastric cancer.

Patients with endoscopically biopsy-proven gastric cancer were prospectively enrolled for imaging on CT and a 3T MRI scanner . The MRI protocol included T2-TSE-BLADE, T2 maps,iShim-DWI(diffusion weighted imaging,DWI)and StarVIBE sequences, and so on. Patients received treatment according to NCCN guideline(the National Comprehensive Cancer Network,NCCN). Readers assigned a TN stage on CT and MRI, and post-operative pathologic confirmation was considered the gold standard.

Inter-reader agreement, the diagnostic accuracy of TN staging on CT and MRI were analyzed and compared to post-operative pathologic TN staging separately. MRI features were analyzed to find the correlation between pretreatment MRI features and response or OS. The study will include 400 patients. Inter-reader agreements of TN staging were analyzed excellent for CT and MRI. Diagnostic accuracy of CT and MRI will be calculated separately.

Inclusion Criteria:

1. Consecutive patients with preoperative pathologically con-firmed gastric cancer by endoscopy and preoperative imaging data (esophagography\CT\EUS\MRI) were included.
2. No contraindications for MRI examination. No contraindications contrast.
3. The patients participate in this study with informed consent.

Exclusion Criteria:

1. The patients couldn't performed MSCT or MR scanning or artefacts affect the evaluation.
2. The patients are extremely anxious and uncooperative about surgery or neoadjuvant therapy .
3. PatientsThe patients refuse to participate in the project.
4. Other situations considered by investigators not meet the inclusion criteria.

Subjects with endoscopically biopsy-proven gastric cancer will receive treatment