BRIEF REPORT No-touch Wedge Ablation Technique of Microwave Ablation for the Treatment of Subcapsular Tumors in the Liver Premal A. Patel, BSc(Hons), MBBS, MRCS, FRCR, Liam Ingram, BSc(Hons), MBChB, Iain D.C. Wilson, MEng(Oxon), BMedSi, MBBS, MRCS, FRCR, and David J. Breen, MBBS, MRCP, FRCR ABSTRACT Ablation of exophytic and border-deforming liver tumors may increase risks of tumor seeding or hemorrhage. The present report describes a no-touch wedge ablation technique intended to potentially reduce tumor disruption while achieving technically adequate ablation. The technique involves the use of multiple probe positions tangential to the tumor, and was used to treat eight tumors. Complete ablation was demonstrated in all cases on early posttreatment imaging at an average of 16 days after the procedure. At an average imaging follow-up of 244 days, there was one case of local tumor recurrence. The technique may be useful for the ablation of exophytic, border-deforming liver tumors. ABBREVIATIONS HCC = hepatocellular carcinoma, RF = radiofrequency Despite the reported success of thermal ablation, tumor seeding has been reported in 0.47%–12% of thermal ablation procedures (1–3). Local tumor progression likely relates to microscopic vascular invasion and satellite micrometastases within 5–10 mm of the tumor. To overcome this, ablation with a margin of 10 mm around the tumor has been recommended (4,5). Subcapsular tumor location has been regarded by some authors as a relative contraindication to thermal ablation as a result of capsular breach by direct puncture and consequent risk of tumor seeding (3,6). Although subcapsular tumor location was not demonstrated to be a signi ficant risk factor for seeding after microwave ablation in one large case series reported by Yu et al (1), the authors still recommended the avoidance of direct tumor punctures without traversing normal parenchyma. An additional reason for increased caution in ablation of subcapsular lesions is the increased risk of hemorrhage (7). The traditional technique for conducting thermal ablation in the liver is to place the probe centrally within small tumors or to perform composite overlapping ablations in larger tumors. This ensures tumor eradication by engul fing the tumor within a composite thermal ablation zone. However, such an ablation can be dif ficult to plan in the setting of subcapsular tumors, the treatment of which often results in direct tumor puncture without crossing normal parenchyma ( 1). The technique described here can be considered for use in liver tumors in a peripheral, subcapsular location. Tumor capsular breach is avoided, and the recommended 5–10- mm ablation margins are achieved. The technique involves probe placement at multiple oblique sites tangential and adjacent to the tumor, creating a sufficient ablation zone that is inclusive of the subcapsular tumor and the required peritumoral margins. The technique aims to minimize the risk of tumor seeding and local tumor progression. MATERIALS AND METHODS Patient selection for microwave ablation was carried out by a multidisciplinary team that included a hepatobiliary surgeon. In accordance with United Kingdom National Health Service National Institute for Health and Clinical Excellence guidelines, which requires active auditing of image-guided tumor ablation, a prospective database of & SIR, 2013 J Vasc Interv Radiol 2013; 24:1257–1262 http://dx.doi.org/10.1016/j.jvir.2013.04.014 None of the authors have identified a conflict of interest. From the Radiology Department, University Hospital Southampton National Health Service Foundation Trust, Southampton General Hospital, Mailpoint 53, C-Level, Centre Block, Southampton SO16 6YD, United Kingdom. Received October 17, 2012; final revision received April 8, 2013; accepted April 10, 2013. Address correspondence to D.J.B.; E-mail: david.breen@uhs.nhs.uk