Real-time conductivity imaging of temperature and tissue property changes during radiofrequency ablation

an ex vivo model using weighted frequency difference

Hun Wi, Alistair L. McEwan, Vincent Lam, Hyung Joong Kim, Eung Je Woo, Tong In Oh*

*Corresponding author for this work

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

We demonstrated the feasibility of time difference and weighted frequency difference conductivity imaging for real-time monitoring of temperature distribution and ablation region estimation during radiofrequency (RF) ablation. The electrical conductivity spectrum of biological tissue reflects mobility of ions in intra- and extra-cellular fluids and changes in cellular morphology induced by heating. The time series conductivity spectra were measured in an ex vivo bovine liver by a high-speed electrical impedance tomography (EIT) system. The EIT system was protected by filters to suppress RF energy and allow interleaved real-time imaging. We recorded time and weighted frequency-difference conductivity images and direct temperature variations at the ablation region and control region during 8min ablation and for the following 66min of cooling. Conductivity variation in regions of interest was compared with temperature recordings. Contours of conductivity change were visualized and compared to estimate the ablation area. EIT images confirmed increase of conductivity at all frequencies and loss of frequency conductivity change associated with loss of cellular structure. Time difference conductivity images showed changes due to both heating during ablation and heat dissipation following ablation together with tissue property changes. Weighted frequency-difference images presented persistent changes following heating due to the morphological change in the ablation zone.

Original languageEnglish
Pages (from-to)277-286
Number of pages10
JournalBioelectromagnetics
Volume36
Issue number4
DOIs
Publication statusPublished - 1 Jan 2015
Externally publishedYes

Keywords

  • Electrical impedance tomography (EIT)
  • RF ablation
  • Temperature distribution
  • Tissue property imaging
  • Weighted frequency difference imaging

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