Effect of Hepatic Perfusion on Microwave Ablation Zones in an Ex Vivo Porcine Liver Model

Siriwardana, Pulathis N.; Singh, Saurabh; Johnston, Edward; Watkins, Jennifer; Bandula, Steve; Illing, Rowland; Davidson, Brian R

doi:10.1016/j.jvir.2016.03.006

Cited by 15 publications

(12 citation statements)

References 22 publications

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“…An organ perfusion system was utilised to study the effect of blood flow and parenchymal perfusion on the incidence of vascular extension following MWA. Microwave ablation zones were morphologically consistent with previous studies [14,16,[20][21][22][23]. There was a central dark zone, surrounded by a white zone and an outer red zone which demonstrated expected characteristics on NADH staining [16].…”

Section: Discussionsupporting

confidence: 88%

“…Microwave ablation zones were morphologically consistent with previous studies [14,16,[20][21][22][23]. There was a central dark zone, surrounded by a white zone and an outer red zone which demonstrated expected characteristics on NADH staining [16]. The dark and white zones were devoid of staining in keeping with non-viable cells representing thermal coagulation and the red zone had patchy NADH staining in keeping with some viability in the boundary of the ablation zone.…”

Section: Discussionsupporting

confidence: 86%

“…Blood was perfused via the hepatic artery and portal vein at a rate of 150 ml/min each for 30 min using a purpose-built dual roller pump (Watson Marlow, Cornwall, UK) perfusion system. The rate of 150 ml/min each via the portal vein and hepatic artery was selected based on the results of a set of preliminary experiments previously designed to select the perfusion rate which provided the optimum peripheral tissue perfusion with minimum or no pressure induced parenchymal damage [16]. Perfusion was continued during MWA in the perfused arm (n ¼ 4) and discontinued in the non-perfused arm (n ¼ 4).…”

Section: Liver Perfusionmentioning

confidence: 99%

“…MWA was performed on healthy porcine livers using an Acculis MTA system with a 2.45 GHz operating frequency, with Acc2i pMTA 14 cm standard applicators (AngioDynamics, Denmead, Hampshire) ( Figure 1). The power selected was 140 W which was delivered for 2 min based on the unit's clinical practice and findings of the previously published preliminary experiments [16]. The MWA probe was inserted into the liver under ultrasound guidance (Hitachi EUB 6500 V R Hitachi, Tokyo, Japan) in order to avoid puncture of large intrahepatic vessels (>6 mm in diameter) akin to clinical practice.…”

Section: Microwave Ablationmentioning

confidence: 99%

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Perivascular extension of microwave ablation zone: demonstrated using an ex vivo porcine perfusion liver model

Singh

Siriwardana

Johnston

et al. 2017

International Journal of Hyperthermia

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Microwave ablation (MWA) has been proposed to suffer less from the heat sink effect compared to radiofrequency ablation but has been reported to cause extension of the ablation zone along intrahepatic vessels in clinical practice. To study this effect in detail, eight fresh porcine livers were perfused in an ex vivo organ perfusion system. Livers were perfused with oxygenated, O-positive human blood at 37 °C. Perfusion was discontinued immediately before ablation in the non-perfused group (n = 4) whilst in the perfused group (n = 4) perfusion was maintained during MWA (140 W X 2 min). Large intrahepatic vessels (> 6 mm) were avoided using ultrasound. MWA zones were bisected within 30 min of perfusion termination and sections were fixed in formalin and stained with H&E and NADH to assess cell viability. Magnetic resonance imaging (MRI) was performed on two livers (one perfused, one non-perfused) to provide imaging correlation before sectioning. Twenty-one out of a total of 30 MW ablation zones (70%) showed extension of the ablation zone along a vessel. There was no statistically significant difference (p = 1) in the incidence of ablation zone extension between perfused (9/13, 69%) and non-perfused organs (12/17, 71%). MRI also demonstrated ablation zone extension along blood vessels correlating with macroscopy in two livers. NADH staining also confirmed extension of the ablation zone. Liver MWA appears to be commonly associated with propagated thermal injury along adjacent vessels and occurs independent of active blood flow. In order to avoid possible complications through non-target tissue injury, this effect requires further investigation.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 86%

Section: Liver Perfusionmentioning

confidence: 99%

Section: Microwave Ablationmentioning

confidence: 99%

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Perivascular extension of microwave ablation zone: demonstrated using an ex vivo porcine perfusion liver model

Singh

Siriwardana

Johnston

et al. 2017

International Journal of Hyperthermia

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“…The CT-based visualization of the central necrotic zone following thermoablation was not explicitly studied previously, as the primary focus of earlier studies was on the identification of ablation margins, overall size assessment or cross-modality comparison of CT to ultrasound, elastography or positron emission tomography (PET) 3,10,14–19 . However, since vital tissue still exists in outer ablation zones and the boundaries of the necrotic areas cannot be reliably extrapolated from the outer shape of the ablation 6,7,20 , the delineation of the outer ablation margins alone is no accurate measure of the success of ablation 9 . Although, as in surgery, a safety zone of 5 mm is recommended for MWA, local recurrence rates are reported to be comparatively higher after ablation 21–23 .…”

Section: Discussionmentioning

confidence: 99%

Improved Visualization of the Necrotic Zone after Microwave Ablation Using Computed Tomography Volume Perfusion in an In Vivo Porcine Model

Bressem

Vahldiek

Erxleben

et al. 2019

Sci Rep

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After hepatic microwave ablation, the differentiation between fully necrotic and persistent vital tissue through contrast enhanced CT remains a clinical challenge. Therefore, there is a need to evaluate new imaging modalities, such as CT perfusion (CTP) to improve the visualization of coagulation necrosis. MWA and CTP were prospectively performed in five healthy pigs. After the procedure, the pigs were euthanized, and the livers explanted. Orthogonal histological slices of the ablations were stained with a vital stain, digitalized and the necrotic core was segmented. CTP maps were calculated using a dual-input deconvolution algorithm. The segmented necrotic zones were overlaid on the DICOM images to calculate the accuracy of depiction by CECT/CTP compared to the histological reference standard. A receiver operating characteristic analysis was performed to determine the agreement/true positive rate and disagreement/false discovery rate between CECT/CTP and histology. Standard CECT showed a true positive rate of 81% and a false discovery rate of 52% for display of the coagulation necrosis. Using CTP, delineation of the coagulation necrosis could be improved significantly through the display of hepatic blood volume and hepatic arterial blood flow (p < 0.001). The ratios of true positive rate/false discovery rate were 89%/25% and 90%/50% respectively. Other parameter maps showed an inferior performance compared to CECT.

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Microwave ablation of liver malignancies: comparison of effects and early outcomes of percutaneous and intraoperative approaches with different liver conditions

et al. 2017

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Liver thermal ablation is an alternative treatment for hepatocellular carcinoma (HCC) and secondary liver malignancies. Microwave ablation (MWA) produces large ablation zones (AZ) in short time; however, AZ prediction is based on preclinical ex vivo models, rising concerns about reproducibility and safety in humans. We aimed to investigate the effects produced by a new-generation MWA system on human liver in vivo with different approaches (percutaneous or intraoperative) and liver conditions (cirrhosis or previous chemotherapy treatment), in comparison with manufacturer-provided predictions based on ex vivo animal models. Complete tumor ablation (CA) and early clinical outcomes were also assessed. From October 2014, 60 consecutive patients (cirrhotic = 31; non-cirrhotic = 10; chemotherapy-treated = 19) with 81 liver nodules (HCC = 31; mets = 50) underwent MWA procedures (percutaneous = 30; laparotomic = 18; laparoscopic = 12), with a 2450 MHz/100 W generator with Thermosphere™ Technology (Emprint™, Medtronic). A contrast-enhanced CT or MR was performed after one month to assess CA and measure AZ. A linear correlation between AZ volumes and ablation times was observed in vivo, without differences from manufacturer-provided ex vivo predictions in all operative approaches and liver conditions. Other independent variables (sex, age, nodule location) showed no relationship when added to the model. Median (IQR) longitudinal and transverse roundness-indexes of the AZs were, respectively, 0.77(0.13) and 0.93(0.11). CA at 1 month was 93% for percutaneous and 100% for intraoperative procedures (p = 0.175). Thirty-day morbidity and mortality were 3% and 0%. MWA with Thermosphere™ Technology produces predictable AZs on human liver in vivo, according to manufacturer-provided ex vivo predictions. In our experience, this new-generation MWA system is effective and safe to treat liver malignancies in different operative and clinical settings.

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Effect of Hepatic Perfusion on Microwave Ablation Zones in an Ex Vivo Porcine Liver Model

Cited by 15 publications

References 22 publications

Perivascular extension of microwave ablation zone: demonstrated using an ex vivo porcine perfusion liver model

Perivascular extension of microwave ablation zone: demonstrated using an ex vivo porcine perfusion liver model

Improved Visualization of the Necrotic Zone after Microwave Ablation Using Computed Tomography Volume Perfusion in an In Vivo Porcine Model

Microwave ablation of liver malignancies: comparison of effects and early outcomes of percutaneous and intraoperative approaches with different liver conditions

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