MRI-temperature mapping during ultrasound prostate ablation using fat for phase estimation.

Referenceless proton resonance frequency (PRF) shift thermometry provides a means to measure temperature changes during minimally invasive thermotherapy that is inherently robust to motion and tissue displacement. In this study, the method is expanded to allow background phase estimation from fatty tissue. A correction scheme for temperature map distortions caused by the ultrasound applicator is developed. The method is tested during thermal ablation of canine prostate using a directional transurethral ultrasound applicator.