Background and Aims Microwave ablation (MWA) for the treatment of hepatocellular carcinoma (HCC) is often performed under ultrasound guidance. MWA in some cases can be completed via a percutaneous approach, while a laparoscopic approach is usually chosen for HCC in special locations. However, laparoscopic MWA also has limitations. For small HCC, isoechoic nodules or target lesions within a cirrhotic background, gray-scale ultrasound (GSUS) is sometimes difficult to locate the target lesions. At this time, contrast-enhanced ultrasound can be used to increase the contrast between the lesions and the liver parenchyma and improve the visibility of the target lesions. However, the time window of enhancement imaging with commonly used contrast agents such as SonoVue is relatively short, so its guiding role in HCC ablation is limited. Sonazoid was approved for use in China in 2019. Compared with other contrast agents, the advantage of Sonazoid is that it can be phagocytosed by Kupffer cells in the liver and has its unique Kupffer phase about 10 min after the injection of contrast agent. At this stage, the ultrasonic imaging of liver parenchyma is enhanced, and previous literature has reported that that Kupffer phase can last for at least 1 h. Meanwhile HCC exhibits low enhancement or no enhancement due to the lack of Kupffer cells. Therefore, intraoperative contrast enhanced ultrasound with Sonazoid (S-CEUS) is theoretically helpful for the localization of the target lesions, and can provide a sufficient time window for MWA. This study was performed to investigate the advantages of S-CEUS in tumor localization compared with GSUS in laparoscopic MWA for HCC in special locations, and analyzed the real-time guiding capability of S-CEUS for ablation.Methods From June 2020 to December 2021, 49 HCC patients undergoing laparoscopic MWA with target lesions located in special areas in Department of Hepatobiliary Surgery, Hunan Provincial People's Hospital/the First Affiliated Hospital of Hunan Normal University were consecutively selected. GSUS and S-CEUS were respectively performed during laparoscopic MWA. The positioning accuracy of the target lesions was analyzed. The 5-point confidence scale was used to evaluate the visibility of the target lesion and the difference of the visibility of the target lesions between GSUS and S-CEUS was compared. At the same time, the duration of Kupffer phase was observed, and the efficacy of MWA performed in this phase was evaluated.Results In the 49 patients, 56 lesions were found by preoperative MRI examination, and 59 lesions were detected by S-CEUS during operation, which were all identified as HCC by aspiration biopsy. The visibility score of target lesions was 2.86±0.96 for GSUS, and was 3.90±0.78 in arterial phase and 4.25±0.60 in Kupffer phase for S-CEUS. The visibility scores of target lesions in both arterial phase and Kupffer phase were better than that in GSUS (both P<0.001), and the visibility score of target lesions in Kupffer phase is better than that in arterial phase (P<0.001). The Kupffer phase lasted more than 1 h; the localization of all lesions in patients with multiple lesions known before operation was completed by injection of the contrast agent in one session; three occult tumors that were not found by preoperative imaging examination were all found in Kupffer phase; all lesions underwent MWA in Kupffer phase. Both immediate evaluation by Sonazoid injection again 15 min after ablation and enhanced MRI examination one month after operation showed that all lesions were ablated completely.Conclusion For laparoscopic MWA of HCC in special locations, the visibilities of target lesions in arterial phase and Kupffer phase of S-CEUS are better than that of GSUS, which is helpful for the localization of target lesions. The Kupffer phase of S-CEUS is helpful for the real-time guidance during performing MWA.