3:18 PM Abstract No. 129 Effect of background liver cirrhosis on performance of a 915-MHz synchronous phased array microwave ablation device: 3D imaging assessment of ablation zone volume and morphology

Abstract

Evaluate impact of liver cirrhosis on synchronous-phased array microwave heating patterns in vivo, and determine if this technology overcomes known limitations of conventional asynchronous MWA devices used for tumor ablation in cirrhotic livers Retrospective, HIPAA-compliant, IRB-approved. Institution records from Jan 1, 2015 thru Aug 31, 2019 revealed total of 100 liver tumor ablations eligible for inclusion. Cirrhosis confirmed by biopsy or elastography. All treatments performed with CT-guidance and consisted of a single application (burn) using 1 or multiple (up to 3) antennae positioned in parallel or cluster array. Antennae positioned under CT-fluoroscopy. Non-contrast volumetric CT documented antennae alignment, spacing, and position immediately before treatment. Treatment parameters obtained from procedural reports. Contrast-enhanced CT obtained immediately posttreatment to define ablation zone margins. 3D imaging software used to postprocess archived volumetric CT data to calculate ablation zone volume, shape and mean margin variance (MMV = expected ablation defect diameter – observed defect diameter) in 3D space. Ablation defect volume and MMV analyzed for identical treatments based on power/duration, antenna type, number and spacing in normal versus cirrhotic liver using generalized mixed modeling (lognormal distribution), and Fishers Exact test. All analyses conducted using SAS 9.4 with PROC GLIMMIX and FREQ (significance P <0.05) There was significant reduction in ablation defect volume and increase in MMV for single-antenna treatments (asynchronous) performed in cirrhotic versus non-cirrhotic liver at same treatment parameters (P = 0.03). No significant difference in defect volume and MMV between cirrhotic versus non-cirrhotic liver when multi-antennae (synchronous-phased emission) ablation performed (P = 0.03). Controlled for antenna number, MMV was significantly larger in cirrhotic liver (P = 0.04) Synchronous-phased array microwave emission performs equally as well in both cirrhotic and non-cirrhotic liver, thereby conferring a more consistent performance advantage of synchronous over conventional asynchronous microwave emission for ablation of tumors in cirrhotic liver.