Comparison of ablation zones among different tissues using 2450-MHz cooled-shaft microwave antenna: results in ex vivo porcine models.
BACKGROUND
For complete tumor ablation in different tissues, it is necessary to investigate the exact coagulation zone of microwave ablation in different tissues. The aim of this study was to compare the extent of microwave ablation zone in muscle, liver and adipose tissue in ex vivo porcine models and assess the shape of microwave coagulation zone among these tissues.


METHODS
Microwave ablations were performed in ex vivo porcine muscle, liver and adipose tissue using 2450-MHz cooled-shaft microwave antenna. The content of water, fat and protein in these three tissues was determined. Two power increments (40 and 80 W) and five time increments (1, 3, 5, 7, and 10 minutes) were used in this study. Diameters and shapes of the ablation zones were assessed on gross specimens.


RESULTS
The average percentages of water, fat and protein in these three tissues were significantly different (P < 0.001), respectively. The long-axis and short-axis diameters among these three tissues at each time-power combination were not significantly different (P > 0.05). The coagulation zones were all elliptical in muscle, liver and adipose tissue. When microwave ablation was performed in the tissue containing both muscle and adipose tissue, the coagulation zone was also elliptical. Regardless of the output power, the ellipticity index (EI) value of 1 minute treatment duration was higher than that of 10 minutes treatment duration (P < 0.05). Furthermore, the EI value did not decrease significantly when the treatment duration was more than 5 minutes (P > 0.05).


CONCLUSIONS
The extent of microwave ablation zones was not significantly different among completely different tissues. Microwave ablations with ≥ 5 minutes time duration can induce coagulation zones with clinical desirable shape. Future clinical studies are still required to determine the role of microwave ablation in different tissues.
Department of Breast Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, Jiangsu, China.
Wenbin
W
Zhou
Mengdi
M
Liang
Hong
H
Pan
Xiaoan
X
Liu
Yanni
Y
Jiang
Yufeng
Y
Wang
Lijun
L
Ling
Qiang
Q
Ding
Shui
S
Wang
D055011:Ablation Techniques; D000273:Adipose Tissue / Q000098:blood supply / Q000473:pathology / Q000528:radiation effects; D000818:Animals; D001777:Blood Coagulation / Q000528:radiation effects*; D004195:Disease Models, Animal; D008099:Liver / Q000098:blood supply / Q000473:pathology / Q000528:radiation effects; D008872:Microwaves / Q000627:therapeutic use*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000473:pathology / Q000528:radiation effects; D009369:Neoplasms / Q000098:blood supply / Q000628:therapy; D013552:Swine