[Controversy and confusion in preoperative imaging precise staging of gastric cancer]

AJCC determined the pathological standards for staging of gastric cancer, but no corresponding radiological signs of a single stage were described or documented. The vacancy of authority standards and limitation of the existing radiological modalities has caused the "stage fright" of the radiologists during the clinical practices. The controversy and confusion under different cognitive aspects can be summarized as follows: (1) If the gastric submucosal layer is not detected, it can only take the indirect standard of "50% thickness ratio" to distinguish T1 and T2. (2) T2 tumors may be overstaged as T3, as a result of the undetectable thin subserosa layer. (3) T3 tumors may be overstaged as T4, because of the inflammatory and fibrosis strands and spiculations near the serosa, and the existence of the gastric bare area. (4) The diagnostic imaging criteria for T4b are still controversial, and the opinions are not uniform about the resectable signs. Some significantly infiltrated unresectable tumors lack typical radiology signs. (5) Size is still the widely-used direct criterion for the diagnosis of lymph node metastasis, however the accuracy of N staging is only 50%-70%. (6) It lacks the typical sign for the diagnosis of early peritoneal metastasis, with a diagnostic sensitivity of only 50%. There is no fundamental breakthrough for the existing imaging modalities to solve the above controversies on the preoperative precise staging. However, the situations can be improved by standardization of the examination and reporting process (oral filling, multi-phase enhancement, multi planar reconstruction, and window width/level technique, etc.), the exploration of the fine signs(hyperattenuating serosa sign, smudge sign, etc.) and the exploration of new modalities (spectral CT, diffusion weighted MR imaging, etc.).