Radiofrequency ablation: effect of surrounding tissue composition on coagulation necrosis in a canine tumor model.

PURPOSE To determine the effect of surrounding tissue type on coagulation necrosis from radiofrequency (RF) ablation in a homogeneous animal tumor model. MATERIALS AND METHODS Thirty canine venereal sarcomas were implanted in three tissue sites (subcutaneous, kidney, and lung) in 13 mildly immunosuppressed dogs. Five of 25 tumors, which were 19 mm +/- 3 (mean +/- SD) in diameter, were allocated to each of five groups: (a) subcutaneous tumors, (b) kidney tumors, (c) lung tumors with blood flow, and (d) subcutaneous and (e) renal tumors without blood flow, which was achieved by sacrificing the animal to eliminate tumor perfusion. A sixth group comprised larger subcutaneous tumors (mean diameter, 46 mm +/- 4) that were also treated. RF ablation was performed with a 1-cm tip and 5 minutes of ablation at 90 degrees C +/- 1. Impedance, temperature, and resultant coagulation diameter were recorded and compared. Data were analyzed statistically, including one-way analysis of variance to determine the effect of tissue conductivity (ie, systemic impedance) on necrosis size and tissue temperatures. Linear regression analysis was used to compare changes in impedance between the control and experimental groups. RESULTS Increasing linear correlation was observed between tumor coagulation diameter and overall baseline system impedance (R(2) = 0.65). RF ablation of lung tumors resulted in the greatest coagulation diameter (13.0 mm +/- 3.5) compared with that in the other groups (P <.01). The smallest coagulation diameter was observed in kidney tumors in the presence of blood flow (7.3 mm +/- 0.6) compared with that in the other groups (P <.01). Elimination of blood flow in kidney tumors increased coagulation diameter to 10.3 mm +/- 0.6 (P <.01). After RF ablation, coagulation diameter in the subcutaneous tumor groups was the same (mean, 9.8 mm +/- 1.0) (difference not significant), regardless of tumor size or presence of blood flow. CONCLUSION The characteristics of tissue that surrounds tumor, including vascularity and electric conductivity, affect ablation outcome. Predominance of tissue-specific characteristics will likely result in site-specific differences in RF-induced coagulation necrosis.

[1]  E F Halpern,et al.  Radio-frequency tissue ablation: effect of pharmacologic modulation of blood flow on coagulation diameter. , 1998, Radiology.

[2]  D M Ikeda,et al.  Radiofrequency ablation of breast cancer: first report of an emerging technology. , 1999, Archives of surgery.

[3]  P. Choyke,et al.  Retroperitoneoscopic-guided radiofrequency ablation of renal tumors. , 2001, The Canadian journal of urology.

[4]  G S Gazelle,et al.  Radiofrequency tissue ablation in the rabbit lung: efficacy and complications. , 1995, Academic radiology.

[5]  S. Goldberg,et al.  Thermal ablation therapy for hepatocellular carcinoma. , 2002, Journal of vascular and interventional radiology : JVIR.

[6]  Y. Ni,et al.  A comparative study on validation of a novel cooled-wet electrode for radiofrequency liver ablation. , 2000, Investigative radiology.

[7]  G. Gazelle,et al.  Thermal ablation therapy for focal malignancy: a unified approach to underlying principles, techniques, and diagnostic imaging guidance. , 2000, AJR. American journal of roentgenology.

[8]  W. Kaiser,et al.  Percutaneous Radiofrequency (RF) Thermal Ablation of Rabbit Tumors Embedded in Fat: A Model for RF Ablation of Breast Tumors , 2001, Investigative radiology.

[9]  G S Gazelle,et al.  Radio-frequency-induced coagulation necrosis in rabbits: immediate detection at US with a synthetic microsphere contrast agent. , 1999, Radiology.

[10]  E. Patterson,et al.  Radiofrequency ablation of porcine liver in vivo: effects of blood flow and treatment time on lesion size. , 1998, Annals of surgery.

[11]  James Sayre,et al.  Effect of vessel size on creation of hepatic radiofrequency lesions in pigs: assessment of the "heat sink" effect. , 2002, AJR. American journal of roentgenology.

[12]  L. Ellis,et al.  Radiofrequency Ablation of Unresectable Primary and Metastatic Hepatic Malignancies: Results in 123 Patients , 1999 .

[13]  J. McGahan,et al.  Radio-frequency electrocautery ablation of mammary tissue in swine. , 2000, Radiology.

[14]  L Solbiati,et al.  Small hepatocellular carcinoma: treatment with radio-frequency ablation versus ethanol injection. , 1999, Radiology.

[15]  H. H. Pennes.  Analysis of tissue and arterial blood temperatures in the resting human forearm. 1948. , 1948, Journal of applied physiology.

[16]  C. Compton,et al.  Radio-frequency tissue ablation of VX2 tumor nodules in the rabbit lung. , 1996, Academic radiology.

[17]  F. Torti,et al.  Radio frequency ablation of lung metastases from renal cell carcinoma. , 2001, The Journal of urology.

[18]  W. Lees,et al.  Survival after percutaneous, image-guided, thermal ablation of hepatic metastases from colorectal cancer , 2000, Diseases of the colon and rectum.

[19]  S. Goldberg,et al.  Image-guided percutaneous chemical and radiofrequency tumor ablation in an animal model. , 2003, Journal of vascular and interventional radiology : JVIR.

[20]  D E Dupuy,et al.  Image-guided radiofrequency tumor ablation: challenges and opportunities--part II. , 2001, Journal of vascular and interventional radiology : JVIR.

[21]  Peter L. Choyke,et al.  PERCUTANEOUS RADIO FREQUENCY ABLATION OF SMALL RENAL TUMORS: INITIAL RESULTS , 2002 .

[22]  K. Otomo,et al.  Successively transplanted canine transmissible sarcoma. , 1979, Gan.

[23]  W W Mayo-Smith,et al.  Percutaneous radiofrequency ablation of malignancies in the lung. , 2000, AJR. American journal of roentgenology.

[24]  D. Han,et al.  Limitations of tetrazolium salts in delineating infarcted brain , 2004, Acta Neuropathologica.

[25]  G. Gazelle,et al.  Hepatocellular carcinoma: radio-frequency ablation of medium and large lesions. , 2000, Radiology.

[26]  S. M. Lobo,et al.  Improved coagulation with saline solution pretreatment during radiofrequency tumor ablation in a canine model. , 2002, Journal of vascular and interventional radiology : JVIR.

[27]  P R Mueller,et al.  Radio-frequency ablation of renal cell carcinoma: early clinical experience. , 2000, Radiology.

[28]  D. Rosenthal.  Percutaneous Radiofrequency Treatment of Osteoid Osteomas , 1997, Seminars in musculoskeletal radiology.

[29]  R E Lenkinski,et al.  Radio-frequency thermal ablation with NaCl solution injection: effect of electrical conductivity on tissue heating and coagulation-phantom and porcine liver study. , 2001, Radiology.

[30]  E F Halpern,et al.  Percutaneous radio-frequency ablation of hepatic metastases from colorectal cancer: long-term results in 117 patients. , 2001, Radiology.

[31]  M. Di Stasi,et al.  Percutaneous radiofrequency ablation of small hepatocellular carcinoma: long-term results , 2001, European Radiology.

[32]  D E Dupuy,et al.  Image-guided radiofrequency tumor ablation: challenges and opportunities--part I. , 2001, Journal of vascular and interventional radiology : JVIR.

[33]  H J Mankin,et al.  Percutaneous Radiofrequency Coagulation of Osteoid Osteoma Compared with Operative Treatment* , 1998, The Journal of bone and joint surgery. American volume.

[34]  G. Dodd,et al.  Radiofrequency thermal ablation: computer analysis of the size of the thermal injury created by overlapping ablations. , 2001, AJR. American journal of roentgenology.

[35]  R. Paczynski,et al.  Automated measurement of infarct size with scanned images of triphenyltetrazolium chloride-stained rat brains. , 1996, Stroke.

[36]  D E Dupuy,et al.  Radiofrequency ablation of spinal tumors: temperature distribution in the spinal canal. , 2000, AJR. American journal of roentgenology.

[37]  Francis A. Duck,et al.  Physical properties of tissue : a comprehensive reference book , 1990 .