Experimental study of large-volume microwave ablation in the liver

Strickland, Andrew; Clegg, Peter; Cronin, N. J.; Swift, Benjamin; Festing, Michael F. W.; West, Kevin; Robertson, G. S. M.; Lloyd, David M.

doi:10.1046/j.1365-2168.2002.02155.x

Cited by 87 publications

(53 citation statements)

References 18 publications

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“…The ablation zones in this study were commensurate with those of previous studies using similar energy delivery. 16,30,31 Brace et al 15 demonstrated that pulsed delivery created larger and more circular ablations compared to continuous delivery of 200 W in porcine kidney in vivo. However, that study utilized a relatively high 67% duty cycle and interpretation of the results was complicated by uncooled applicators and inconsistency in the power generation system.…”

Section: Discussionmentioning

confidence: 99%

Microwave ablation energy delivery: Influence of power pulsing on ablation results in an ex vivo and in vivo liver model

et al. 2014

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Purpose: The purpose of this study was to compare the impact of continuous and pulsed energy deliveries on microwave ablation growth and shape in unperfused and perfused liver models. Methods: A total of 15 kJ at 2.45 GHz was applied to ex vivo bovine liver using one of five delivery methods (n = 50 total, 10 per group): 25 W continuous for 10 min (25 W average), 50 W continuous for 5 min (50 W average), 100 W continuous for 2.5 min (100 W average), 100 W pulsed for 10 min (25 W average), and 100 W pulsed for 5 min (50 W average). A total of 30 kJ was applied to in vivo porcine livers (n = 35, 7 per group) using delivery methods similar to the ex vivo study, but with twice the total ablation time to offset heat loss to blood perfusion. Temperatures were monitored 5-20 mm from the ablation antenna, with values over 60• C indicating acute cellular necrosis. Comparisons of ablation size and shape were made between experimental groups based on total energy delivery, average power applied, and peak power using ANOVA with post-hoc pairwise tests. Results: No significant differences were noted in ablation sizes or circularities between pulsed and continuous groups in ex vivo tissue. Temperature data demonstrated more rapid heating in pulsed ablations, suggesting that pulsing may overcome blood perfusion and coagulate tissues more rapidly in vivo. Differences in ablation size and shape were noted in vivo despite equivalent energy delivery among all groups. Overall, the largest ablation volume in vivo was produced with 100 W continuous for 5 min (265.7 ± 208.1 cm 3 ). At 25 W average, pulsed-power ablation volumes were larger than continuous-power ablations (67.4 ± 34.5 cm 3 versus 23.6 ± 26.5 cm 3 , P = 0.43). Similarly, pulsed ablations produced significantly greater length (P ≤ 0.01), with increase in diameter (P = 0.09) and a slight decrease in circularity (P = 0.97). When comparing 50 W average power groups, moderate differences in size were noted (P ≥ 0.06) and pulsed ablations were again slightly more circular. Conclusions: Pulsed energy delivery created larger ablation zones at low average power compared to continuous energy delivery in the presence of blood perfusion. Shorter duty cycles appear to provide greater benefit when pulsing. C

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Section: Discussionmentioning

confidence: 99%

Microwave ablation energy delivery: Influence of power pulsing on ablation results in an ex vivo and in vivo liver model

et al. 2014

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“…Adequately powered 915-MHz and 2.45-GHz systems can create relatively large ablation zones, but the longer wavelength at 915 MHz typically results in a longer ablation zone (28,34,(36)(37)(38). In general, the greatest heating from any system occurs within 1 cm of the antenna.…”

Section: Heat-based Ablationmentioning

confidence: 99%

Percutaneous Tumor Ablation Tools: Microwave, Radiofrequency, or Cryoablation—What Should You Use and Why?

Hinshaw¹,

Lubner²,

Ziemlewicz³

et al. 2014

RadioGraphics

292

213

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“…Numerous studies have investigated the effects of MW on liver parenchyma in in vivo models (Table 1) ( [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In all of them, the ablated area consisted macroscopically of two different zones with a central white pale area and a 1-3 mm brown perilesional capsule (5,9,11,13,16,(19)(20)(21).…”

Section: Macroscopic Anatomymentioning

confidence: 99%

Hepatic microwave ablation: a review of the histological changes following thermal damage

Gravante

Ong

Metcalfe

et al. 2008

Liver International

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Microwave (MW) ablation therapy is a local treatment by which tumours are destroyed by coagulation from the passage of MWs into cells. The aim of this review is to examine histological results obtained from preclinical and clinical studies. A literature search was undertaken for all studies focusing on MW therapy and in which lesions were excised for a complete histopathological examination after treatment. Two main zones were described after ablative therapy (central and transitional Microwave (MW) coagulation therapy is a form of local ablation where tumours are destroyed by thermal coagulation that develops from the passage of MWs into cells and the production of frictional movement between molecules (1). Initially developed in the early 1980s to achieve haemostasis along the plane of transection during hepatic resections (2), MW coagulation of tissue surfaces proved slower than electrocautery units and produced deeper areas of tissue necrosis. These two characteristics, while making MW unsuitable for operative haemostasis, are potentially useful in the ablation of liver tumours. Like radiofrequency (RF) ablation and laser-induced interstitial thermotherapy, MW is very versatile and can be performed percutaneously using ultrasound or computed tomography (CT) guidance, or at laparoscopy or laparotomy with intra-operative ultrasound guidance.The formation of the thermal lesion during the ablation process is a complex combination of MW energy absorption, heating conduction and possible tissue water evaporation, condensation and movement. In 2002, Izzo (3) suggested that the production of very small zones of coagulative necrosis by the intratumoral MW-emitting needle electrodes would require frequent repositioning at 5-10 mm intervals to create multiple overlapping zones of coagulative necrosis. He also suggested that MW should not be performed near major bile ducts and blood vessels because of the description of vascular and biliary complications in these locations. However, since the appearance of that review, numerous technical advances have been introduced in MW engineering and subsequently evaluated histologically in a number of preclinical and clinical studies.The aim of this review is to examine those studies and determine the factors that influence the production of an area of ablation and the evidence for its use under different circumstances. Materials and methodsA literature search was undertaken for all studies focusing on MW ablative therapy where lesions were excised for a complete histopathological examination after the treatment.Articles were selected from the MEDLINE, EMBASE and Cochrane Library databases, using the key words microwave, ablation or ablative therapy, liver, hepatic, in vivo, ex vivo, clinical, experimental. Only articles published in the English literature were used. We

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Experimental study of large-volume microwave ablation in the liver

Abstract: This novel microwave system allows the ablation of large volumes of liver tissue in a short period of time. The ability to produce lesions reproducibly and safely highlights the potential of this system in the future treatment of irresectable liver tumours.

Cited by 87 publications

References 18 publications

Microwave ablation energy delivery: Influence of power pulsing on ablation results in an ex vivo and in vivo liver model

Microwave ablation energy delivery: Influence of power pulsing on ablation results in an ex vivo and in vivo liver model

Percutaneous Tumor Ablation Tools: Microwave, Radiofrequency, or Cryoablation—What Should You Use and Why?

Hepatic microwave ablation: a review of the histological changes following thermal damage

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