Susceptibility artifact correction in MR thermometry during microwave ablation of liver lesions

Motivation: Safe and efficient thermoablation of liver lesions requires accurate real-time MR-thermometry as feedback for the operator. Goal(s): Improved relative MR-thermometry based on proton resonance frequency shift by correcting artifacts originating from susceptibility changes applied in real-time respiratory-triggered EPI during microwave ablation of the liver. Approach: Solving the Laplacian boundary value (LBV) problem as well as the total field inversion (TFI) method to phase difference maps before extracting the temperature change maps. In-vivo microwave ablation sessions in 5 patients have been retrospectively corrected. Results: In all 5 patients, LBV robustly removed susceptibility artifacts in proximity of the heated area, while TFI tended to overfit. Impact: Susceptibility artifact correction improves real-time MR thermometry guidance of thermoablation therapies of patients with liver lesions. More accurate temperature maps will provide increased safety during the ablation and improve efficiency by ensuring sufficient thermal dose delivery to the target tissue.