Hepatic radiofrequency ablation with internally cooled probes: effect of coolant temperature on lesion size

• Published in: IEEE transactions on biomedical engineering Vol. 50; no. 4; pp. 493 - 500
• Main Authors: Haemmerich, D., Chachati, L., Wright, A.S., Mahvi, D.M., Lee, F.T., Webster, J.G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2003; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Animals; Biological and medical sciences; Catheter Ablation - instrumentation; Catheter Ablation - methods; Cattle; Cold Temperature; Computer Simulation; Coolants; Cooling; Electrodes; Equipment Failure Analysis - methods; Finite Element Analysis; Finite element methods; In Vitro Techniques; Lesions; Liver; Liver - physiopathology; Liver - surgery; Liver Neoplasms - physiopathology; Liver Neoplasms - surgery; Medical sciences; Metastasis; Minimally invasive surgery; Probes; Radio frequency; Sensitivity and Specificity; Temperature; Temperature distribution; hepatic ablation; bipolar ablation; RF ablation; finite-element method; RFA; radiofrequency ablation; Ablation; multiprobe; liver ablation
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2003.809488

Radiofrequency (RF) ablation is a minimally invasive method for treatment of primary and metastatic liver tumors. One of the currently commercially available devices employs an internally cooled 17-gauge needle probe. Within the probe, cool water is circulated during ablation, which cools tissue close to the probe resulting in larger lesions. We evaluated the effect of different cooling water temperatures on lesion size. We created a finite-element method model, simulated 12 min impedance-controlled ablation and determined temperature distribution for three water temperatures. Lesion diameters in the model were 33.8, 33.4, and 32.8 mm for water temperatures of 5/spl deg/C, 15/spl deg/C, and 25/spl deg/C, respectively. We solved a simplified model geometry analytically and present dependence of lesion diameter on cooling temperature. We further performed ex vivo experiments in fresh bovine liver. We created four lesions for each water temperature, with the same water temperatures as used in the finite-element method (FEM) model. Average lesion diameters were 28.3, 30, and 29.5 mm for water temperatures of 5/spl deg/C, 15/spl deg/C, and 25/spl deg/C, respectively. Water temperature did not have a significant effect on lesion size in the ex vivo experiments (p=0.76), the FEM model, and the analytical solution.