Contribution of Diffusion Weighted MRI to Diagnosis and Staging in Gastric Tumors and Comparison with Multi-detector Computed Tomography
Aim: Comparing diagnostic performance of diffusion-weighted imaging (DWI) and multi-detector computed tomography (MDCT) for TNM (Tumor, Lymph node, Metastasis) staging of gastric cancer.
Materials and Methods: We used axial T2-weighted images and DWI (b-500 and b-1000 s/mm2) protocol on 51 preoperative patients who had a diagnosis of gastric cancer. We also conducted multi-detector computed tomography (MDCT) examinations. We looked for a signal increase in the series of DWI images. The depth of tumor invasion in stomach wall (tumor (T) staging), the involvement of lymph nodes (nodal (N) staging), and presence or absence of metastases (metastatic staging) in DWI and CT images according to TNM staging system were evaluated. In each diagnosis of the tumors, sensitivity, specificity, positive and negative accuracy rates of DWI and MDCT examinations were found through a comparison with the results of the surgical pathology, which is the gold standard method. In addition to the compatibilities of each examination with surgical pathology was examined using kappa statistics.
Results: Sensitivity and specificity of DWI and MDCT in lymph node staging were as follows: N1: DWIMR: 75.0%, 84.6%; MDCT: 66.7%, 82%; N2: DWIMR: 79.3%, 77.3%; MDCT: 69.0%, 68.2%; N3: DWIMR: 60.0%, 97.6%; MDCT: 50.0%, 90.2%.The diagnostic tool DWI seemed more compatible with the gold standard method (surgical pathology), especially in the staging of lymph node, when compared to MDCT. On the other hand, in T staging, the results of DWI and MDCT were better than the gold standard when the T stage increased. However, DWI did not demonstrate superiority to MDCT. The sensitivity and specificity of both imaging techniques for detecting distant metastasis were 100%.
Conclusion: The diagnostic accuracy of DWIMRI for TNM staging in gastric cancer before surgery is at a comparable level with MDCT and adding DWI to routine protocol of evaluating LN metastasis might increase diagnostic accuracy.