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Local specific absorption rate in brain tumors at 7 tesla
Matthew C Restivo1, Cornelis A T van den Berg1, Astrid L H M W van Lier1
1Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands.
Magnetic Resonance in Medicine
|March 11, 2015
Summary
Simulations using healthy patient models may underestimate specific absorption rate (SAR) in brain tumor patients. Accurate MR safety assessments require patient-specific models to account for abnormal tissue properties.
Area of Science:
- Medical Imaging
- Biomedical Engineering
- Computational Electromagnetics
Background:
- Magnetic Resonance (MR) imaging safety at 7 Tesla (T) relies on accurate numerical simulations of radiofrequency electromagnetic fields.
- Current simulations typically use healthy patient models, which may not reflect the altered dielectric properties of brain tumors.
Purpose of the Study:
- To assess the impact of brain tumors on local specific absorption rate (SAR) using patient-specific models.
- To determine if healthy patient models are adequate for estimating SAR in brain tumor patients.
Main Methods:
- Constructed patient-specific brain tumor models from high-grade glioma patient scans.
- Assigned tumor dielectric properties based on electrical properties tomography data.
- Performed numerical simulations to calculate local SAR distributions.
Main Results:
- Local SAR increased within tumors by up to 30% compared to healthy tissue.
- The location of maximum 10-gram averaged SAR often remained outside the tumor.
- Peak local SAR estimation increased when tumor models were placed at the site of maximum electric field intensity.
Conclusions:
- Peak local SAR estimations using healthy patient models may underestimate actual SAR in brain tumor patients.
- Patient-specific modeling is crucial for accurate MR safety assessments in oncology patients.
