This study demonstrates a safe and effective profile of US-guided MWA combined with artificial pleural effusion and/or ascites in the treatment of hepatic neoplasms adjacent to high-risk structures. There were no major complications, and only six cases with minor complications among 25 patients were treated with MWA. The serum levels of ALT, AST and AFP remarkably decreased after ablation for 3, 6, and 12 months, respectively. Furthermore, the volume reduction ratio of the ablation lesions considerably increased during the follow-up period.
As a minimally invasive and effective treatment, microwave ablation has been characterized as a simple operation that causes less trauma and is repeatable; moreover, it has been identified as one of the major curative methods for liver cancer [8]. Recently, it has been widely accepted that the therapeutic effect of minimally invasive treatment is equal to that of radical resection [9] and that minimally invasive treatment is less invasive and promotes quick recovery [10, 11]. Our previous studies have elucidated that the cumulative 1-, 3-, and 5-year survival rates are 92%, 72%, and 51% in 288 patients with liver cancer treated with microwave ablation, respectively [12]. However, due to the limitation of ultrasound, hepatic neoplasms adjacent to high-risk structures such as the gastrointestinal tract, gallbladder, diaphragm and macrovessels may not be clearly displayed, which has become a great challenge in ultrasound-guided microwave ablation. Artificial pleural effusion and ascites have been reported to improve the visibility of ultrasound and reduce the relevant complications during ablation treatment [13]. The injected ascites is absorbed within one week in most patients [14]. Additionally, to overcome the shortcomings of 2D imaging techniques, 3D-based thermal ablation has been applied in preoperative treatment planning. Previous studies have addressed the problem of modeling the thermal field of microwave ablation theoretically, and a simple approach for preoperative planning of MWA has been developed [15, 16]. Doctors can repeatedly perform surgical planning on individualized 3D models, optimize surgical plans, and improve surgical skills and safety. This novel modality not only complies with surgeons’ operating habits, but also avoids the defect of inaccurate judgment in the ultrasound-guided 2D space [17]. Based on the 3D thermal field preoperative planning, the ablation needle layout, ablation thermal field range and ablation duration are planned ahead, which could minimize the ablation needle insertion pathways and avoid the risk of repeated puncture [18, 19]. Consistently, in our study, we combined 3D image processing and analysis methods, trajectory planning, and thermal modeling planning with navigation technology to establish a 3D visualization preoperative treatment planning system for microwave ablation of hepatic neoplasms adjacent to high-risk structures. Moreover, the success rate of artificial pleural effusion and ascites injection was 88–100%, and no serious complications related to artificial ascites injection occurred. Furthermore, 21 patients achieved a successful separation of liver tumors from adjacent high-risk structures, which provided sufficient space for microwave ablation and ensured subsequent operation. Moreover, the artificial pleural effusion and ascites were completely absorbed within 3 days after microwave ablation. Assisted by artificial pleural and ascites, MWA achieved a radical resection rate of 93.7% with a good prognosis during the follow-up period. Therefore, the application of a 3D visualization preoperative treatment planning system for MWA in hepatic neoplasms assisted by artificial pleural effusion and ascites could serve as a safe and effective method.
Minimally invasive microwave or radiofrequency ablation procedures have a significantly lower rate of complications than surgery has. Several major complications, including liver abscess, empyema, bile duct injury, colon perforation, tumor seeding, hemorrhage and skin burns, mainly occur in neoplasms adjacent to high-risk structures [20]. For instance, liver cancer adjacent to high risk sites, has a high probability of diaphragm perforation or abdominal cavity organ perforation after microwave ablation, which could also lead to acute peritonitis, severe abdominal infection, multiorgan failure, and other severe complications [21]. Meanwhile, liver tumors abutting high-risk locations such as large blood vessels, extrahepatic heat-sensitive organs and the hepatic caudate lobe are prone to cause thermal ablation damage. Furthermore, ultrasound cannot penetrate gas or bone, which has a great influence on microwave ablation and limits the treatments for tumors at special locations [22, 23]. In this study, artificial pleural effusion and/or ascites injections were successfully performed, and only a few treated patients had minor complication and all recovered with symptomatic treatment, suggesting that US-guided microwave ablation assisted by artificial pleural effusion and ascites is a safe and effective adjuvant treatment strategy that can reduce damage to high-risk near tumors.