title: CT-based temperature monitoring during hepatic RF ablation: feasibility in an animal model.
abstract: OBJECTIVE
  The aim of this paper was to establish non-invasive CT-based temperature monitoring during hepatic radiofrequency (RF) ablation in an ex vivo porcine model followed by transfer of the technique into a feasibility in vivo experiment.
  
  
  METHODS
  Bipolar RF ablations were performed in 10 specimens of porcine liver. Parallel to the needle-shaped RF applicator three optical temperature probes were inserted into the liver specimens at fixed distances of 5, 10 and 15 mm from the RF probe. During energy application (20 W) unenhanced sequential MSCT scans were acquired using the following scan protocol: 140 kV tube voltage, 300 mAs/rotation tube current time product, collimation 24 × 1.2 mm, rotation time 0.5 s. Axial image data was reconstructed using a soft tissue convolution kernel. Temperature data was recorded during every CT scan. Using a circular 0.5 cm(2) region of interest local CT values were measured at the tips of the temperature probes and matched with the measured temperatures. Regression analysis was performed to analyse the relationship between local temperatures and CT values for each temperature probe position. Furthermore, the same experimental design was used in four anaesthetised female pigs in order to investigate the potential of this technique for an in vivo application.
  
  
  RESULTS
  A negative correlation was found for the relationship between temperature and CT value. Regression coefficients were -0.44 (5 mm), -0.35 (10 mm) and -0.37 (15 mm) for ex vivo data. Analysis of in vivo experiments showed regression coefficients between -0.025 and -0.434.
  
  
  CONCLUSIONS
  Multislice computed tomography is able to depict temperature changes in liver tissue during RFA.
authors.affiliation: Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 30 Aachen, Germany. bruners@rad.rwth-aachen.de
authors.forename: Philipp
authors.initials: P
authors.lastname: Bruners
authors.forename: Ganga D
authors.initials: GD
authors.lastname: Pandeya
authors.forename: Elena
authors.initials: E
authors.lastname: Levit
authors.forename: Eva
authors.initials: E
authors.lastname: Roesch
authors.forename: Tobias
authors.initials: T
authors.lastname: Penzkofer
authors.forename: Peter
authors.initials: P
authors.lastname: Isfort
authors.forename: Bernhardt
authors.initials: B
authors.lastname: Schmidt
authors.forename: Marcel J W
authors.initials: MJ
authors.lastname: Greuter
authors.forename: Matthijs
authors.initials: M
authors.lastname: Oudkerk
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitz-Rode
authors.forename: Christiane K
authors.initials: CK
authors.lastname: Kuhl
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D005260:Female; D008099:Liver / Q000601:surgery*; D023421:Models, Animal; D061330:Multidetector Computed Tomography; D013552:Swine; D013696:Temperature