Comparison of Ablation Zones among Different Tissues Using 2450-MHz Cooled-Shaft Microwave Antenna: Results in Ex Vivo Porcine Models

Abstract

BackgroundFor 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.Materials and MethodsMicrowave 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.ResultsThe 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).ConclusionThe 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.

Ultrasound-guided percutaneous microwave ablation for benign breast lesions: evaluated by contrast-enhanced ultrasound combined with magnetic resonance imaging

“…The breast is the perfect organ for ablation because the breast locates in superficial location, cover only by skin with no intervening structures, can be compressed asymmetrically to achieve ablation strategy and monitored effectively by US (6). MWA is a promising minimally invasive local therapy with many advantages, including large ablation zones, short ablation durations, and improved convection profile (7)(8)(9). Currently, MWA has been explored in clinical practice, which destroys tumors in situ by means of thermal coagulation or protein denaturation (10).…”

Modeling of the dielectric properties of biological tissues within the histology region

“…For example, it includes most microwave imaging systems, with frequencies spanning 1.3 GHz to 8 GHz [2], [4], [22]- [25]. It also encompasses general ablation systems (2.45 GHz, [7], [20]) and proposed breast hyperthermia (4.2-4.5 GHz, [6]). Since the breast is a highly heterogeneous organ that is commonly investigated, accurate knowledge of the Histology Region is particularly relevant.…”

From diagnosis to therapy in lung cancer: management of CT detected pulmonary nodules, a summary of the 2015 Chinese-German Lung Cancer Expert Panel

“…The reason is that the extent of MWA zones was not significantly different among completely different tissues, such as liver, adipose tissues, and muscles (18). MWA with ≥5 minutes' time duration can induce coagulation zones with clinical relevant shape.…”

“…For RFA complete ablation was in 78-96% in tumors <2 cm, but however, in tumors >2 cm there was seen a shorter PFS and a high recurrence rate. Using MWA has the advantage that if the tumor <5 cm, complete ablation resulted in 95% of patients (18)(19)(20)(21).…”