Tissue shrinkage in microwave thermal ablation: comparison of three commercial devices. (19th May 2018)

• Record Type: Journal Article
• Authors: Farina, Laura; Nissenbaum, Yitzhak; Cavagnaro, Marta; Goldberg, S. Nahum
• Is Part Of: International journal of hyperthermia. Volume 34:Number 4(2018)
• Page Start: 382
• Page End: 391
• Publication Date: 2018-05-19
• Subjects: Microwave thermal ablation -- tissue shrinkage -- tissue characterisation; Thermotherapy -- Periodicals; 615.832
• DOI: 10.1080/02656736.2017.1362115
• Languages: English
• ISSNs: 0265-6736

Abstract

Abstract: Purpose : To evaluate, characterise and compare the extent of tissue shrinkage induced from three different commercial microwave ablation devices, and to elucidate the mechanism behind the distinctive performances obtained. Materials and methods: Microwave ablation ( N = 152) was conducted with three different commercial devices on cubes of ex vivo liver (10–40 ± 2 mm/side) embedded in agar phantoms. 50–60 W was applied for 1–10 min duration. Pre- and post-ablation dimensions of the samples, as well as the extent of carbonisation and coagulation were measured and correlated. ANOVA was performed to evaluate statistical significance. Results: For all devices, logarithmic correlations with time were observed for both tissue shrinkage ( R 2 = 0.84–1.00) and induced carbonisation ( R 2 = 0.73–0.99) radially to the antenna axis. Along the longitudinal axis of the antenna, for two of the devices shrinkage did not appreciably change with time ( p > 0.05), yet carbonisation increased linearly ( R 2 = 0.57–0.94). For the third fully internally-cooled device, both carbonisation and shrinkage showed logarithmic trends ( R 2 = 0.85–0.98 and R 2 = 0.78–0.94, respectively) based upon delayed carbonisation appearing only 5 min into ablation and onward. For all devices, non-uniform shrinkage was noted within the coagulated area increasing from the boundary of the ablated area (14%) to the limit of carbonisation (39%) in a linear fashion ( R 2 = 0.88) Conclusions: Microwave ablation device construction can alter the extent of post-ablation coagulation and tissue shrinkage. Given that tissue shrinkage in the coagulated area shows non-uniform behaviour, observed differences can be attributed in part to the applicator cooling system that alters the ablation temperature profile.