title: An analytic method to predict the thermal map of cryosurgery iceballs in MR images.
abstract: This paper presents a newly developed method to estimate, in magnetic resonance (MR) images, the temperatures reached within the volume of an iceball produced by a cryogenic probe. Building on the direct measurements of the MR signal intensity and its correlation with independent temperature variations at the phase transition from liquid to solid, the thermal information embedded in the images was accessed. The volume and diameter of the growing iceball were estimated from a time series of MR images. Using regressions over the volume in the time and thermal domains, this method predicted the cryogenic temperatures beyond the range of sensitivity of the MR signal itself. We present a validation of this method in samples of gelatin and ex vivo pig liver. Temperature predictions are shown to agree with independent thermosensor readings over a range extending from 20 degrees C down to -65 degrees C, with an average error of less than 6 degrees C.
authors.affiliation: iMRI group of the Centre Hospitalier, Universitaire de Québec, Quebec, QC G1L 3L5, Canada. fournial@gel.ulaval.ca
authors.forename: Romain
authors.initials: R
authors.lastname: Fournial
authors.forename: Amidou S
authors.initials: AS
authors.lastname: Traoré
authors.forename: Denis
authors.initials: D
authors.lastname: Laurendeau
authors.forename: Christian
authors.initials: C
authors.lastname: Moisan
mesh_terms: D000465:Algorithms; D000818:Animals; D001831:Body Temperature; D003452:Cryosurgery / Q000379:methods*; D007053:Ice; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D066298:In Vitro Techniques; D008099:Liver / Q000503:physiopathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013552:Swine; D013817:Thermography / Q000295:instrumentation / Q000379:methods*
chemical_list: D007053:Ice