title: Specific CT 3D rendering of the treatment zone after Irreversible Electroporation (IRE) in a pig liver model: the "Chebyshev Center Concept" to define the maximum treatable tumor size.
abstract: BACKGROUND
  Size and shape of the treatment zone after Irreversible electroporation (IRE) can be difficult to depict due to the use of multiple applicators with complex spatial configuration. Exact geometrical definition of the treatment zone, however, is mandatory for acute treatment control since incomplete tumor coverage results in limited oncological outcome. In this study, the "Chebyshev Center Concept" was introduced for CT 3d rendering to assess size and position of the maximum treatable tumor at a specific safety margin.
  
  
  METHODS
  In seven pig livers, three different IRE protocols were applied to create treatment zones of different size and shape: Protocol 1 (n = 5 IREs), Protocol 2 (n = 5 IREs), and Protocol 3 (n = 5 IREs). Contrast-enhanced CT was used to assess the treatment zones. Technique A consisted of a semi-automated software prototype for CT 3d rendering with the "Chebyshev Center Concept" implemented (the "Chebyshev Center" is the center of the largest inscribed sphere within the treatment zone) with automated definition of parameters for size, shape and position. Technique B consisted of standard CT 3d analysis with manual definition of the same parameters but position.
  
  
  RESULTS
  For Protocol 1 and 2, short diameter of the treatment zone and diameter of the largest inscribed sphere within the treatment zone were not significantly different between Technique A and B. For Protocol 3, short diameter of the treatment zone and diameter of the largest inscribed sphere within the treatment zone were significantly smaller for Technique A compared with Technique B (41.1 ± 13.1 mm versus 53.8 ± 1.1 mm and 39.0 ± 8.4 mm versus 53.8 ± 1.1 mm; p < 0.05 and p < 0.01). For Protocol 1, 2 and 3, sphericity of the treatment zone was significantly larger for Technique A compared with B.
  
  
  CONCLUSIONS
  Regarding size and shape of the treatment zone after IRE, CT 3d rendering with the "Chebyshev Center Concept" implemented provides significantly different results compared with standard CT 3d analysis. Since the latter overestimates the size of the treatment zone, the "Chebyshev Center Concept" could be used for a more objective acute treatment control.
authors.forename: Dominik
authors.initials: D
authors.lastname: Vollherbst
authors.forename: Stefan
authors.initials: S
authors.lastname: Fritz
authors.forename: Sascha
authors.initials: S
authors.lastname: Zelzer
authors.forename: Miguel F
authors.initials: MF
authors.lastname: Wachter
authors.forename: Maya B
authors.initials: MB
authors.lastname: Wolf
authors.forename: Ulrike
authors.initials: U
authors.lastname: Stampfl
authors.forename: Daniel
authors.initials: D
authors.lastname: Gnutzmann
authors.forename: Nadine
authors.initials: N
authors.lastname: Bellemann
authors.forename: Anne
authors.initials: A
authors.lastname: Schmitz
authors.forename: Jürgen
authors.initials: J
authors.lastname: Knapp
authors.forename: Philippe L
authors.initials: PL
authors.lastname: Pereira
authors.forename: Hans U
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Jens
authors.initials: J
authors.lastname: Werner
authors.forename: Boris A
authors.initials: BA
authors.lastname: Radeleff
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany. christof.sommer@med.uni-heidelberg.de.
authors.forename: Christof M
authors.initials: CM
authors.lastname: Sommer
mesh_terms: D000818:Animals; D018274:Electroporation / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging*; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*