The usefulness of diffusion-weighted imaging (DWI) for the detection of gastric cancer

Diffusion-weighted imaging (DWI) is already utilized in the important clinical diagnosis of brain ischemia and also for differentiating brain abscesses from metastatic brain tumors. Recent technical developments make DWI of the body feasible. Several studies have revealed the usefulness of DWI for the diagnosis of liver, ovary, parotid gland, kidney, and breast tumors. We herein present cases of gastric cancer detected by DWI and discuss the efficacy of DWI for the diagnosis of gastric cancer.

We performed DWI, enhanced computed tomography (CT) and endoscopic examinations on 15 patients with gastric cancer. MR examinations were performed using the 1.5-T imager (Toshiba). We measured the signal intensity in a series of DWI images and calculated the apparent diffusion coefficient (ADC) values in order to differentiate the tumors from normal tissues and inflammations. Two experienced radiologists evaluated the depth of tumor invasion into the gastric wall (tumor staging), the involvement of regional lymph nodes (nodal staging), and the presence or absence of metastasis (metastatic staging) on DWI and CT images according to the TMN classification system. TMN staging of each tumor was compared with the pathologic and surgical findings.

There were no differences between the DWI and the CT images regarding their abilities to detect advanced gastric cancer. However, DWI could detect peritoneal dissemination, liver metastasis, lymph nodes metastasis without any enhancement material more clearly than CT.

DWI is therefore considered to have the potential to be clinically effective for the evaluation of preoperative TMN staging of gastric cancer.