A new system of microwave ablation at 2450 MHz: preliminary experience

Abstract

The aim of this study was to assess the feasibility of the application of the new system (Emprint Microwave Ablation System, Covidien Boulder, CO, USA) and to identify its advantages. In particular the attention was focused to the spherical ablation zone obtained and its usefulness in terms of effectiveness. The new system is composed of: a 2450 MHz generator that delivers a maximum power of 100 W, a fiberglass antenna and a pump for internally cooled antenna. Ten liver nodules (8 hepatocellular carcinomas and 2 metastasis) were percutaneously treated (mean diameter 24.9 mm, range 16-35 mm). Technical success, ablation duration time, overall procedure time and safety were registered. To define the shape of the ablation zone, multiplanar reformatting (MPR) was performed. Roundness index transverse was calculated: a value near 1 represents a more spherical ablation zone shape, and a value distant from 1 implies an oval configuration. Technical success was 100%. Mean ablation time was of 3.85 min (range 3-5 min), mean overall procedure time was 30.5 min (range 25-40 min). No major complications were recorded. Roundness index transverse presented a mean value of 0.94, meaning that a spherical shape of ablation zone was achieved. One of the most promising innovations of the new microwave technology is the spherical shape of the ablation volume that could be related with an improving of the effectiveness and safety.

The Emprint™ Ablation System with Thermosphere™ Technology: One of the Newer Next-Generation Microwave Ablation Technologies

“…The roundness index transverse was 0.94, meaning that a spherical zone of ablation was consistently achieved. 8 The authors have encountered similar results. ►Fig.…”

“…7 In fact, the most predictable sizes and zones of ablation were achieved at 100 W. Ierardi et al published one of the earliest in vivo series of patients treated with the Emprint Ablation System. 8 These authors demonstrated that the Emprint Ablation System produced technically successful reliable spherical zones of ablation in a short period of time. Ten liver nodules (8 hepatocellular carcinomas and 2 metastases), with a mean diameter of 24.9 mm, were treated percutaneously.…”

A comparison between 915 MHz and 2450 MHz microwave ablation systems for the treatment of small diameter lung metastases

“…Completely cooling the active tip increases antenna reliability and prevents tissue sticking (thermal control). The homogeneous environment around the radiator also prevents the wavelength changes caused by tissue desiccation close to the active tip, thus avoiding comet-shaped ablations (wavelength control) (11,12,17).…”

“…The publications currently available concerning the HF system are scarce and consist of an ex vivo temperature monitoring study and one percutaneous and two laparoscopic liver ablation patient series (11,(18)(19)(20). To the best of our knowledge, no reports regarding lung ablations with the new HF system are available.…”

Microwave ablation of hepatocellular carcinoma

“…RFA rapidly became the gold standard in ablation, especially in the treatment of small HCC nodules, at first flanking and eventually replacing percutaneous ethanol injection (PEI) treatments [10] . However, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks [20,21] : Over the last 5 years, these limitations have been effectively tackled by second and third generation MWA systems, with considerably enhanced characteristics both in terms of treatment controllability and of overall coagulative performance [22][23][24][25] . The purpose of this review is: (1) to provide a brief overview of the key physical and technical aspects of MWA and of the currently available systems; and (2) to gather and discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA.…”