Patent ID: 8706190
Filing Date: 2014-04-22
Classification: G01R

Abstract:
1. A method for magnetic resonance imaging based temperature monitoring for real-time feedback to a physician for a cryoablation therapy of a lesion which creates an ice ball of the lesion to induce cell death, a border of the ice ball having a water physical state, comprising the steps of: with a magnetic resonance imaging system, performing proton resonance frequency (PRF) imaging and obtaining a real-time gradient echo sequence (GRE) phase temperature image of the ice ball of the lesion undergoing the cryoablation therapy and surrounding tissue adjacent the lesion; applying an algorithm to said real-time gradient echo sequence phase temperature image that corrects temperature errors at said border of the ice ball, said temperature error correction correcting susceptibility contrast errors caused by a distortion of a local magnetic field resulting from differences in susceptibility between frozen tissue and non-frozen tissue, said algorithm accounting for the susceptibility differences by simulating susceptibility artifacts, wherein said susceptibility differences are determined by searching for a minimum of a cost function defined as a standard deviation at a corrected temperature series, the border of the ice ball being assumed to have a water physical state transition temperature so that the algorithm corrects phase data for the gradient echo sequence phase temperature image for said susceptibility artifacts; and said algorithm comprising the following wherein T wherein φ=MR-phase data, α=thermal coefficient, TE=echo time B Y=gyromagnetic ratio, k FT=Fourier Transformation, and ΔX=Susceptibility contrast matrix.