Combination Therapies: Quantifying the Effects of Transarterial Embolization on Microwave Ablation Zones
Erica M. Knavel, M.D., Christopher L. Brace, Ph.D., Paul F. Laeseke M.D., Ph.D.
There is increasing interest in combining transarterial embolization (TAE) and thermal ablation for treating large, poorly visualized, or infiltrative hepatocellular carcinomas.
Improved oncologic outcomes are demonstrated when compared with either therapy alone with several retrospective studies demonstrating improved overall survival (OS), improved recurrence-free survival and decreased rate of disease progression with combination therapy (TACE combined with MW or RF ablation) compared to ablation alone for the treatment of HCC.1-6
No data exists regarding the effect of transarterial embolization on the size, shape and reproducibility of subsequent microwave ablations.
The purpose of this study is to quantify the effect of TAE on microwave ablations in an in vivo porcine liver model.
Methods & Materials:
Femoral arterial approach arteriograms and cone beam CT scans were performed to delineate hepatic arterial anatomy and identify individual branches supplying each of the four liver lobes in 6 female domestic swine.
Two of the four liver lobes were embolized to near stasis (5 beat stasis) with 100-300μm Embosphere® Microspheres (Merit Medical Systems, Inc., South Jordan, UT).
Microwave ablations (65 W, 5 min) were created in both embolized (TAE-MW, n=15) and non-embolized (MW, n= 12) portions of the liver using a 2.45 GHz system and single antenna (Certus 140 and PR-15, NeuWave Medical, Inc., Madison WI).
A mixed effects model was used to compare the TAE-MW and MW groups.
Performing TAE prior to microwave ablation increases ablation zone diameter and area by approximately 27% and 66%, respectively.
This size increase is due to an increase in the size of the peripheral portion of the ablation zone, which is most susceptible to perfusion mediated cooling and heat sinks.
Further studies are warranted to characterize the effect of particle size, timing of the embolization, and different microwave power/time combinations on the resultant ablation zones.
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