The contrast-enhanced ultrasound (CEUS)-guided method in combination with Sonazoid has not been clinically or experimentally evaluated with regard to its use for identifying sentinel lymph node (SLN) in the stomach. Therefore, we attempted to evaluate the usefulness of the CEUS-guided method with Sonazoid for imaging of the lymphatic channels and SLN of the stomach in a porcine model by comparing it with the conventional Evans blue dye-guided method. Twenty-eight 2 to 3-month-old swine weighing 17-30 kg were used in this experiment. Anesthesia was maintained with 2.0-3.0% isoflurane/O 2 inhalation. Sonazoid was injected into the intra-and sub-mucosal layers of the stomach. The intragastric or transcutaneous CEUS-guided method was used to identify the lymphatic channels and SLN of the stomach. Contrast imaging using the CEUS-guided method with Sonazoid enabled us to produce clear images of the afferent lymph vessel and SLN of the stomach until 2 h after the injection of Sonazoid. In addition, intranodal flow of the microbubble agent could be clearly identified using tissue linear harmonic images of the SLN. The SLN detection rate was not significantly different between the CEUS-and dye-guided methods. However, the Evans blue dye flowed out quickly (15 min after the injection) through the true SLN into the next LN of stomach. In conclusion, the use of the CEUS-guided method with Sonazoid might be the most useful clinical procedure for producing real-time images of the SLN of the stomach, and the linear harmonic images are also useful for evaluating intranodal structure within the SLN. (Cancer Sci 2011; 102: 2073-2081 T he sentinel lymph node (SLN) is the first lymph node that receives drainage from a primary tumor. Morton et al.( 1) initially demonstrated the SLN concept in a feline model and later confirmed it in a clinical study of patients with breast cancer and melanoma. The clinical impact of the SLN concept has become one of the most important topics in surgical oncology.(1-3) Recently, gastric cancer has also been identified as a target for SN navigational surgery (SNNS). The dye-guided or radioisotope (RI)-guided method, or a combination of both, is conventionally used for SLN mapping in gastric cancer.(4-10) The dye-guided method is convenient and safe. However, it has been reported to be associated with a high false negative node ratio because the small dye particles can readily diffuse through the true SLN and transverse multiple nodes.(4-10) The RI-guided method has several advantages over the dye-guided method for identifying SLN. However, lymph vessels cannot be visualized. The high radioactivity at the primary injection site might also interfere with the intraoperative detection of nearby lymph nodes. (11,12) Recently, contrast-enhanced ultrasonography in combination with Sonazoid was adopted to detect the SLN in patients with breast cancer.(13) However, the clinical usefulness of the CEUS-guided method in combination with Sonazoid is still controversial, because the superiority of the CEUS-guided m...