MR Thermometry with High Precision and Temporal Resolution by Quadratic Phase MR Fingerprinting

Motivation: Proton resonance frequency (PRF)-shift thermometry is the current standard for MR-temperature monitoring in interventional procedures. However, the long TE required for phase contrast induces signal dropout and increases sensitivity to metal and motion artifacts. Goal(s): Use quadratic RF phase (qRF) MR fingerprinting to image off-resonance frequency for thermometry at a real time frame rate. Approach: Because PRF change is much more sensitive to temperature change in aqueous tissue than T1/T2, we propose a “lightweight” constant low-flip-angle MRF sequence optimized for 3s or less frame rate to measure temperature from the PRF shift. Results: We implemented qRF-MRF thermometry with high spatiotemporal resolution. Impact: A thermometry method with high temporal resolution that does not suffer from signal dropout at high temperatures can enable more accurate temperature monitoring for MR-guided interventional procedures. Additionally, it has potential to be more robust to motion artifacts.