Quantitative MR thermometry based on phase-drift correction PRF shift method at 0.35 T.

Area of Science:

• Medical Imaging
• Biophysics
• Interventional Radiology

Background:

• Noninvasive magnetic resonance thermometry (MRT) using proton resonance frequency shift (PRFS) is crucial for monitoring ablation temperatures.
• Low-field MR scanners offer advantages for interventional procedures due to their open configuration.

Purpose of the Study:

• To investigate the feasibility and accuracy of quantitative MR thermography during hyperthermia.
• To evaluate a phase-drift correction PRFS method with first-order polynomial fitting in a 0.35 T open MR scanner.

Main Methods:

• Evaluated optimal polynomial order for phase-drift correction PRFS using unheated phantoms and ex vivo porcine liver.
• Tested temperature estimation in healthy volunteers and ex vivo porcine liver microwave ablation.
• Compared PRFS-derived temperature changes with fiber optic probe measurements during ablation.

Main Results:

• First-order polynomial fitting achieved the lowest temperature root mean square error (RMSE) across all experiments.
• In porcine liver ablation, temperature errors between MRT and fiber optic probe were <2°C for most points.
• Overall RMSE for temperature points during ablation was 1.49°C.

Conclusions:

• MR thermometry with phase-drift correction PRFS is suitable for monitoring temperature during microwave ablation.
• The technique is effective in a low-field, open-configuration whole-body MR scanner.
• This method enables accurate, noninvasive temperature monitoring in interventional procedures.