The Ability Of Diffusion Weighted Imaging In Displaying Stomach Cancer

Objective: To investigate the application of diffusion weighted imaging(DWI)in abdomen; the ability of diffusion weighted imaging(DWI)in displaying stomach cancer and determine the best b values.Materials and methods: Single shot echo planar imaging(EPI)diffusion weighted sequences at 1.5T MR scanner (b=400,600,800,1000 and 1200 s/mm~2)were performed in 18 patients with stomach cancer. Stomach tissue were examined pathologically from 15 patients to confirm the stomach cancer.3 patients have been diagnosed with gastroscop. The DWI imaging parameters were: TE/TR 60/3000 ms; FOV 300-380mm; Slice thickness 6 mm. The signal intensity of tumor tissue,normal gastric wall and background noise, mean apparent diffusion coefficient(ADC) values and signal to noise ratio (SNR)of tumors , contrast to noise ratio(CNR)of tumors and normal gastric wall were calculated and compared.Results: The mean ADC values of tumor were decreased following the ascending of b values.The CNR of tumors and normal stomach wall decreases following the descending of b values,and the CNR in the DWI with b=400,600,800,1000,1200s/mm~2 was significantly higher than that in T2 weighted imaging. The SNR in the DWI with b=400,600,800,1000 s/mm~2 was significantly higher than that in DWI with b=1200 s/mm2 and T2 weighted imaging,but the SNR in T2 weighted imaging was higher than that in DWI with b=1200 s/mm2.Conclusion: (1) The mean ADC values of tumor were decreased following the ascending of b values(b=400,600,800,100and1200s/mm~2) . The mean ADC values of tumor are affected obviously by blood perfusion. (2) b=1000 s/mm~2 is reasonable for DWI of stomach cancer,and that can get rid of the influence produced by blood perfusion.(3) The DWI with b=400,600,800,1000 s/mm~2 not only has the higher SNR and CNR but also can distinguish the tumor tissue Clearly.