title: Heat distribution in the spinal canal during radiofrequency ablation for vertebral lesions: study in swine.
abstract: OBJECTIVE
  To prospectively evaluate the safety of radiofrequency (RF) ablation for vertebral lesions by monitoring the temperature in swine vertebral models with and without a cortical bone defect.
  
  
  METHODS
  The institutional animal care and use committee approved the animal studies. In vivo and ex vivo studies were performed. In the in vivo study, 20 lumbar vertebrae from six swine were locally heated by using 1- or 2-cm active-tip internally cooled electrodes. In the ex vivo study, 12 fresh pig cadaver lumbar vertebrae were extracted from four swine, and spinal tumor models with or without cortical bone defect were created by stuffing a cavity with muscle tissue and locally heated by using a 1-cm active-tip internally cooled electrode. The temperature was monitored in the spinal canal and around the vertebral body during ablation. Mann-Whitney U test was used to indicate a significant difference between groups by using 1- and 2-cm active tip in the in vivo study and between groups with and without cortical defect in the ex vivo study.
  
  
  RESULTS
  In the in vivo study in which 1- and 2-cm active-tip needles were used, the temperature in the spinal canal rose to 38.2 degrees C +/- 2.7 (standard deviation) and 45.5 degrees C +/- 6.2, respectively. The latter was significantly higher than the former (P < .001). In the ex vivo study in which tumor models with or without a cortical bone defect were used, the temperature in the spinal canal rose to 48.4 degrees C +/- 6.2 and 31.3 degrees C +/- 3.4, respectively. The former was significantly higher than the latter (P < .001).
  
  
  CONCLUSIONS
  For in vivo cases with a 2-cm active tip and ex vivo cases with a vertebral posterior bone defect, the temperature rose to over 45 degrees C, potentially injuring the spinal cord and peripheral nerves.
authors.affiliation: Department of Pathophysiological and Therapeutic Science, Division of Radiology, Faculty of Medicine, Tottori University, 36-1 Nishicho, Yonago, Tottori 683-8504, Japan. july1st@grape.med.tottori-u.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Adachi
authors.forename: Toshio
authors.initials: T
authors.lastname: Kaminou
authors.forename: Toshihide
authors.initials: T
authors.lastname: Ogawa
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kawai
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Takaki
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Sugiura
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Ohuchi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hashimoto
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D006358:Hot Temperature; D011446:Prospective Studies; D015641:Radiography, Interventional; D013115:Spinal Canal / Q000000981:diagnostic imaging / Q000601:surgery*; D018709:Statistics, Nonparametric; D013552:Swine