Ex vivo tissue-type independence in proton-resonance frequency shift MR thermometry.
The temperature sensitivity of the proton-resonance frequency (PRF) has proven valuable for the monitoring of MR image-guided thermal coagulation therapy. However, there is significant inconsistency in reported values of the PRF-thermal coefficient, as measured from experiments encompassing a range of in vivo and ex vivo tissue types and experimental conditions. A method of calibrating the temperature dependence of the PRF is described and results are presented that indicate a tissue-type independence. To this end, other possible mechanisms for variations in the PRF-thermal coefficient are suggested, including physiological perturbations and volume magnetic susceptibility effects from geometry and orientation.
Peters
R D
RD
Department of Medical Biophysics, University of Toronto, Sunnybrook Health Science Center, Ontario, Canada.
Hinks
R S
RS
Henkelman
R M
RM
D000818:Animals; D002138:Calibration; D003199:Computer Systems; D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D019047:Phantoms, Imaging; D011817:Rabbits; D013552:Swine; D013821:Thermometers