Current perspectives on microwave ablation of liver lesions in difficult locations

Abstract

Microwave ablation (MWA) is becoming the standard of care in treating liver lesions smaller than 3 cm benefiting from a plethora of radiofrequency ablation (RFA) data in the literature. Some of the advantages of MWA compared to RFA are as follows: Faster ablations, more reproducible and predictable heating, better thermal conductivity in different liver tissue environments, and less susceptibility to heat-sink effect. Despite its many advantages, there are still concerns regarding MWA use in high-risk locations such as near portal veins, near the bile ducts, and near the heart. Some centers have historically considered these tumor locations as a contraindication to percutaneous thermal ablation. In this review, we summarize the current data on the safety of MWA of liver tumors in challenging locations. We also discuss several technical tips with examples provided.

Ablation versus Radiation Segmentectomy for Small Liver Tumors

“…10 Historically, certain high-risk locations, such as adjacent to the portal veins, bile ducts, and heart, were considered prohibitive for thermal ablation; however, recent studies showed encouraging results that MWA in such areas is relatively safe and effective when precaution is used. 5,11,12 While the literature provides evidence supporting the safety of utilizing MWA in challenging locations like proximity to the heart, near the diaphragm, and adjacent to the hepatic hilum, additional precautionary measures can be performed based on the skill and experience of the proceduralist to enhance safety. 5,11,12 Numerous retrospective evaluations have indicated that the combination of transarterial chemoembolization (TACE) and ablation could potentially yield oncological outcomes comparable to surgical resection, particularly for lesions smaller than 3 cm.…”

“…5,11,12 While the literature provides evidence supporting the safety of utilizing MWA in challenging locations like proximity to the heart, near the diaphragm, and adjacent to the hepatic hilum, additional precautionary measures can be performed based on the skill and experience of the proceduralist to enhance safety. 5,11,12 Numerous retrospective evaluations have indicated that the combination of transarterial chemoembolization (TACE) and ablation could potentially yield oncological outcomes comparable to surgical resection, particularly for lesions smaller than 3 cm. One meta-analysis found that combination of interventional therapies such as TACE and RFA seem to be more effective than RFA alone.…”

“…5 11 12 While the literature provides evidence supporting the safety of utilizing MWA in challenging locations like proximity to the heart, near the diaphragm, and adjacent to the hepatic hilum, additional precautionary measures can be performed based on the skill and experience of the proceduralist to enhance safety. 5 11 12…”

“…3 According to BCLC, if LT is not possible, the first approach should be thermal ablation. 5 The second stage (BCLC-A) is characterized by either a single HCC, regardless of its size, or multiple HCCs with a maximum of three nodules, each not exceeding 3 cm in size. 3 Per the 2022 BCLC guideline updates, in addition to chemoembolization, transarterial radioembolization (TARE) could be considered in patients with single nodules ≤8 cm.…”

Thermal Ablation in the Liver: Heat versus Cold—What Is the Role of Cryoablation?

“…Liver tumors are predominantly treated using heat-based ablation, and in the United States MWA has largely replaced RFA, with cold-based techniques via cryoablation used much less commonly. 1,2 Early cryoablation techniques in the liver used an open surgical method in conjunction with large probes and nitrogen cryogen. [3][4][5] A retrospective analysis of these early procedures in liver tumors raised concerns about cryoshock and hemorrhage that influenced the subsequent era of thermal ablation procedures, and cryoablation was relegated as a riskier alternative to RFA.…”