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Simultaneous proton resonance frequency shift thermometry and T1 measurements using a single reference variable flip
Bryant T Svedin1, Allison Payne1, Dennis L Parker1
1Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah.
Magnetic Resonance in Medicine
|January 18, 2019
Summary
This study introduces a novel method for simultaneous MR thermometry in both aqueous and fatty tissues using proton resonance frequency (PRF) shift and T1 measurements. This advancement improves safety and efficacy in thermal interventional treatments.
Area of Science:
- Magnetic Resonance Imaging
- Biomedical Engineering
- Medical Physics
Background:
- Accurate real-time temperature monitoring is crucial for MR-guided thermal therapies.
- Proton resonance frequency (PRF) shift is sensitive to temperature changes in aqueous tissues but not fatty tissues.
- T1-weighted imaging can provide temperature information in fatty tissues, but lacks the temporal resolution of PRF.
Purpose of the Study:
- To develop and validate a single reference variable flip angle method for simultaneous PRF and T1 measurements.
- To achieve equivalent temporal resolution for both PRF and T1 thermometry.
- To enable simultaneous temperature monitoring in both aqueous and fatty tissues during MR-guided interventions.
Main Methods:
- A single reference variable flip angle approach was employed, acquiring one reference image at a low flip angle and dynamic images at a higher flip angle.
- Monte Carlo simulations determined the optimal flip angle for combined PRF and T1 measurements.
- The method was validated using MR-guided focused ultrasound heating experiments in phantoms and cadaveric tissue, and in vivo measurements in healthy volunteers.
Main Results:
- Simultaneous PRF and T1 measurements demonstrated good qualitative agreement in space and time within aqueous tissues.
- Temperature-induced T1 changes were successfully measured in fatty tissue, showing the expected temporal response.
- A compromise flip angle was selected to optimize signal-to-noise ratio for both PRF and T1 measurements.
Conclusions:
- The developed method reliably enables simultaneous PRF and T1 thermometry, overcoming the limitations of PRF in monitoring temperature in adipose tissues.
- Future calibration of T1 change to temperature will allow for real-time fat thermometry.
- This technique has the potential to enhance patient safety and treatment efficacy in thermal interventional procedures.
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