Abstract: In order to perform accurate lymph node excision ,we ought to resect all metastatic lymph nodes and keep normal lymph nodes. This challenge the present examinational methods of lymph node metastasis before and during operation. In the past, the CT、MRI、PET-CT have low accuracy and specificity, poor and false negative rate , in order to achieve the goal infrared electronic endoscope, high resolution PET-CT、MRI equipments and high polymer nanoparticles molecular targeted imaging contrast agents have been developed.

Key words: Gastric cancer, Lymph node metastasis, Magnetic resonance imaging, Molecular imaging