Three-dimensional assessment of vascular cooling effects on hepatic microwave ablation in a standardized ex vivo model

Abstract

The aim of this study was a three-dimensional analysis of vascular cooling effects on microwave ablation (MWA) in an ex vivo porcine model. A glass tube, placed in parallel to the microwave antenna at distances of 2.5, 5.0 and 10.0 mm (A–V distance), simulated a natural liver vessel. Seven flow rates (0, 1, 2, 5, 10, 100, 500 ml/min) were evaluated. Ablations were segmented into 2 mm slices for a 3D-reconstruction. A qualitative and quantitative analysis was performed. 126 experiments were carried out. Cooling effects occurred in all test series with flow rates ≥ 2 ml/min in the ablation periphery. These cooling effects had no impact on the total ablation volume (p > 0.05) but led to changes in ablation shape at A–V distances of 5.0 mm and 10.0 mm. Contrary, at a A–V distance of 2.5 mm only flow rates of ≥ 10 ml/min led to relevant cooling effects in the ablation centre. These cooling effects influenced the ablation shape, whereas the total ablation volume was reduced only at a maximal flow rate of 500 ml/min (p = 0.002). Relevant cooling effects exist in MWA. They mainly depend on the distance of the vessel to the ablation centre.

Comparison of the Therapeutic Efficacy and Technical Outcomes between Conventional Fixed Electrodes and Adjustable Electrodes in the Radiofrequency Ablation of Benign Thyroid Nodules

“…Effective ablation of feeding vessels is crucial to therapeutic and technical success because feeding vessels are responsible for nodule regrowth. The heat-sink effect by feeding vessels makes complete ablation challenging; it may be associated with vessel size and the distance between the vessel and the ablation zone [ 25 ]. Furthermore, in cases of hypervascular nodules, feeding arteries can cause intranodular and peri-nodular hemorrhage, which exacerbates the heat-sink effect and hinders effective RFA.…”

Pigs: Large Animal Preclinical Cancer Models

“…Pigs have been used to study transplantation, immunity pre- and postnatally, stress, allergies, transmittable diseases, vaccination, and cancer [ 92 ]. There has been considerable use of percutaneous thermal ablation by radiofrequency [ 41 ] or microwave [ 42 , 43 ] based methods for the treatment of primary and metastatic hepatic malignancies using pig models. Pig models have been used to study the heat sink effect caused by vessels located close to the target area of ablation.…”

“…Orthotopic implantation of ko HCC cell in Oncopig model [37,38] Prevention of liver precancerous and cancerous lesions Model of hereditary tyrosinemia type-1 treatment with in vivo lentiviral vector targeting human fumarylacetoacetate hydrolase transgene Fumarylacetoacetate hydrolase -/via somatic cell transfer [39] Immune therapy Thermal ablation methods Ex vivo pig livers [41][42][43] Vaccine-induced peptide-specific cytotoxic T-cell responses…”