Microwave ablation with a triaxial antenna: results in ex vivo bovine liver

Brace, Christopher L.; Laeseke, Paul F.; Weide, Daniel W. van der; Lee, F.T.

doi:10.1109/tmtt.2004.839308

Cited by 110 publications

(62 citation statements)

References 22 publications

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“…The three antenna failures encountered in this study may have been because of overuse or fabrication errors in these handmade antennas; failures were observed only in previously used antennas. Subsequent zones of ablation created with the same antenna tend to be slightly decreased in diameter compared with former zones (11). Thus, no antenna was used in more than one animal.…”

Section: Discussionmentioning

confidence: 99%

“…The microwave ablation system (Micrablate, Madison, Wis) used in this study has a 17-gauge tunable triaxial antenna specifically developed to minimize power reflection without adding to the diameter of the antenna (11,12). A biopsy insertion needle is used to introduce the antenna.…”

Section: Advances In Knowledgementioning

confidence: 99%

“…All microwave ablations in this study were performed by using a single 17-gauge triaxial antenna as previously designed and characterized in an ex vivo liver model (11,12). Microwave power originated from a commercially available 2.45-GHz magnetron generator (MG0300D; Cober-Muegge, Norwalk, Conn) capable of delivering up to 300 W of continuous-wave power.…”

Section: Microwave Ablationmentioning

confidence: 99%

“…The value of 1 mm was chosen on the basis of past experience indicating that vessels smaller than 1 mm are coagulated quickly and provide little or no heatsinking effect. The value of 2.0 cm was used on the basis that ex vivo zones of ablation are rarely larger than 4.0 cm in diameter and numeric predictions that in vivo zones of ablation would be 20%-30% smaller because of the effects of perfusion (11). A perfusion score (S p ) was then calculated foreach representative slice according to the equation…”

Section: Measurement Of Ablation Zone Size and Shapementioning

confidence: 99%

See 3 more Smart Citations

Microwave Ablation with a Single Small-Gauge Triaxial Antenna: In Vivo Porcine Liver Model

Brace¹,

Laeseke²,

Sampson³

et al. 2007

Radiology

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Purpose-To evaluate the performance of a 17-gauge triaxial antenna at microwave ablation in an in vivo porcine liver model. Materials and Methods-This study was approved by the institutional animal care and use committee. Thirteen female domestic pigs (mean weight, 45 kg) were used. Ablations were performed with a prototype microwave ablation system and triaxial antenna by using a constant, continuous-wave power of 68 W for 2 (n = 6), 3 (n = 6), 4 (n = 6), 5 (n = 6), 6 (n = 6), 7 (n = 13), 10 (n = 7), and 12 (n = 8) minutes. Animals were euthanized after ablation, livers were removed, and ablation zones were sliced and measured for size and roundness. A mixed linear model with animals modeled as random effects was used to test for significant differences in ablation zone metrics among time groups; post hoc tests were used to detect significant differences between time groups.Results-Mean ablation zone diameters ranged from 2.05 cm ± 0.23 (standard deviation) at 2 minutes to 2.59 cm ± 0.53 at 12 minutes. Thirteen (32%) of 40 ablation zones with mean maximum diameters greater than 3.0 cm were observed at the 5-12-minute time groups. No significant differences in ablation zone diameter were observed among all groups (P > .05), but a trend of increasing diameter with time was noted. Mean isoperimetric ratio (a measure of roundness) for all ablation zones was 0.88 ± 0.02, which indicates minimal heat sinking near vessels. Conclusion-The triaxial microwave ablation system is capable of creating relatively large, circular zones of ablation in minutes with minimal effects from local blood flow.Thermal tumor ablation is a rapidly expanding treatment option for neoplasms of many organs, including the lung, liver, bone, and kidney (1-6). Tumor ablation has gained considerable attention due to its minimally invasive nature and the large number of patients who are not candidates for potentially curable surgical resection because of comorbidities or tumor number, size, or location. Radiofrequency (RF) ablation accounts for most of the clinical and experimental studies in heat-based ablation techniques (7). Unfortunately, current RF ablation systems are limited by the need to keep temperatures below 100°C to prevent charring, long Advances in Knowledge• To our knowledge, we reported the first preclinical experience of microwave ablation with a triaxial antenna. • A functional relationship between application time and ablation diameter in a normal in vivo liver model was defined.• We described a way to quantify perfusion in a zone of ablation (perfusion score).• We quantified the limited heat-sink effect with the triaxial microwave ablation antenna through circularity measurements.Microwave ablation shares many of the advantages of RF ablation but has additional theoretic advantages that may offer better and more consistent destruction of tumors. Microwaves have a much broader field of power density and a correspondingly larger zone of active heating (8). This may allow for more uniform tumor killing within a targeted ...

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Section: Discussionmentioning

confidence: 99%

Section: Advances In Knowledgementioning

confidence: 99%

Section: Microwave Ablationmentioning

confidence: 99%

Section: Measurement Of Ablation Zone Size and Shapementioning

confidence: 99%

See 2 more Smart Citations

Microwave Ablation with a Single Small-Gauge Triaxial Antenna: In Vivo Porcine Liver Model

Brace¹,

Laeseke²,

Sampson³

et al. 2007

Radiology

View full text Add to dashboard Cite

show abstract

“…Early coaxial antennas developed for MWA yielded ablation zones resembling a 'tear drop', as opposed to the desired spherical shape [9]. More recent MWA probes were designed to minimize probe size, maximize ablation zone size, minimize detrimental heating of the feedline and yield more spherical lesions, by minimizing impedance mismatch [10][11][12].…”

Section: Microwave Ablationmentioning

confidence: 99%