Patent ID: 8706190

Claim:
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 Δ ⁢ ⁢ T corr ⁡ ( r → ) ⁡ [ º ⁢ ⁢ C . ] = Δ ⁢ ⁢ T PRF ⁡ ( r → ) ⁡ [ º ⁢ ⁢ C . ] + 1  α  · FT - 1 [ ( 1 3 - k z 2 k x 2 + k y 2 + k z 2 ) · FT ⁡ [ Δ χ ⁡ ( r → ) ] wherein T corr ({right arrow over (R)}) is the corrected temperature, T PRF ⁡ ( r → ) = ϕ ⁢ ⁢ frozen - ϕ ⁢ ⁢ unfrozen α · γ · B 0 · TE wherein φ=MR-phase data, α=thermal coefficient, TE=echo time B 0 =main magnetic field, Y=gyromagnetic ratio, k x , k y , k z =k-space coordinates FT=Fourier Transformation, and ΔX=Susceptibility contrast matrix.