Use of diffusion-weighted imaging to evaluate histological factors and proliferative potential of gastric cancer

Objective: Gastric cancer is one of the most common malignant tumors. Non-inversional tool could improve the diagnosis and treatment of the cancer. The aim of this study was to evaluate the diagnostic value of diffusion-weighted imaging (DWI) for histological factors and Ki-67 antigen labelling index (LI) in gastric cancer. Methods: Eight-four DWI images of gastric cancer were analyzed retrospectively at b values of 0 and 1000 s/mm2, respectively. Postoperative histological factors were obtained, including tumor TNM stage, histological type, and differentiation degree. Mean ADC values were calculated for the gastric cancers by two radiologists. Relations between ADC values and histological factors or Ki-67 LI were analyzed. The diagnostic cutoffs of ADC value were determined using ROC analysis and used to distinguish histological factors and Ki-67 LI of gastric cancer. Results: The ADC values in the tumors of different TNM stage, histological type, and Ki-67 LI were significantly different. They were significantly lower in higher TNM stage tumors, poorly differentiated adenocarcinomas or signet-ring cell carcinomas, and in the cancers with elevated Ki-67 LI. The ADC value was inversely correlated with Ki-67 LI (r = -0.8146, P < 0.01). The diagnostic cut-offs of ADC values to distinguish stage I, well differentiated adenocarcinoma and cancer with Ki-67 LI < 47% were 1.025, 1.042 and 0.961×10-3 mm2/s, respectively. Conclusions: ADC value may be helpful as a noninvasive tool for evaluating the histological factors and Ki-67 LI of gastric cancer.