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Non-invasive temperature mapping using MRI: comparison of two methods based on chemical shift and T1-relaxation
F Bertsch1, J Mattner, M K Stehling
1Institut für Radiologische Diagnostik, Ludwig Maximilians Universität, München, Germany. Bertsch@ikra.med.uni-muenchen.de
Magnetic Resonance Imaging
|July 17, 1998
Summary
Non-invasive MRI temperature mapping using chemical shift and T1 relaxation shows accuracy in homogeneous media. Fat-containing tissues present challenges for accurate temperature calculation with these MRI methods.
Area of Science:
- Biomedical Engineering
- Medical Imaging
- Physics
Background:
- Accurate temperature monitoring is crucial for thermal therapies.
- Magnetic Resonance Imaging (MRI) offers non-invasive temperature mapping potential.
- Chemical shift (CS) and T1 relaxation are MRI parameters sensitive to temperature changes.
Purpose of the Study:
- To implement and evaluate the accuracy of MRI-based temperature mapping using CS and T1 relaxation.
- To assess performance in various media heterogeneity during thermal energy deposition.
- To compare focal and external heating methods.
Main Methods:
- Utilized a 1.5 T clinical MRI scanner.
- Measured temperature dependence of water proton chemical shift and T1 relaxation.
- Employed homogeneous gel and heterogeneous muscle phantoms, heated focally and externally (20-50°C).
- Compared MRI data with fiberoptic temperature readings.
Main Results:
- Both CS and T1 methods showed accuracy in homogeneous media (CS: ±1.5°C, T1: ±2.0°C).
- CS method accuracy was ±0.6°C in gel.
- Accuracy decreased in heterogeneous media with fat (T1: ±3.5°C, CS: +5°C).
- T1 method accuracy was within 1.5°C during focal heating of muscle.
Conclusions:
- Chemical shift MRI is more accurate in fat-free homogeneous media.
- Temperature calculation in fatty tissues remains challenging with these MRI techniques.