Absolute MR thermometry using time-domain analysis of multi-gradient-echo magnitude images

Area of Science:

• Medical Imaging
• Biophysics
• Spectroscopy

Background:

• Magnetic Resonance Imaging (MRI) enables absolute temperature measurements using spectral resonances where frequency difference (Delta f(T)) correlates with temperature.
• Multi-gradient-echo (MGE) sequences offer high temporal and spatial resolution for acquiring spectroscopic data in MRI.

Purpose of the Study:

• To advance MRI thermometry by developing postprocessing techniques for MGE data.
• To investigate the direct computation of Delta f(T) from MGE signals in the time domain for absolute temperature mapping.

Main Methods:

• Applied time-domain analysis to the magnitude of multi-gradient-echo signals for MR thermometry.
• Conducted in vitro experiments for proof of concept in generating absolute temperature maps.
• Performed ex vivo bone marrow experiments using fat resonance as a reference for temperature mapping.

Main Results:

• Successfully retrieved absolute temperature maps from time-domain analysis of MGE magnitude images.
• Demonstrated the technique's insensitivity to magnetic field drift and local field disturbances.
• Validated the determination of Delta f(T) in bone marrow using the fat resonance reference.

Conclusions:

• The developed postprocessing method allows for direct Delta f(T) calculation from MGE magnitude signals, enhancing MR thermometry.
• This novel approach provides robust and accurate absolute temperature mapping, suitable for various biological tissues.