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Improved whole-brain SNR with an integrated high-permittivity material in a head array at 7T
Karthik Lakshmanan1,2, Giuseppe Carluccio1,2, Jerzy Walczyk1,2
1Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.
Magnetic Resonance in Medicine
|March 23, 2021
Summary
High-permittivity material (HPM) helmets enhance brain MRI signal-to-noise ratio (SNR) across the entire brain. This technology improves both transmit efficiency and receive-side SNR, even in challenging central brain regions.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Biomedical Engineering
- Materials Science
Background:
- Improving signal-to-noise ratio (SNR) in brain MRI is crucial for detailed diagnostics.
- Conventional methods often struggle to enhance SNR uniformly throughout the entire brain, especially in central regions.
Purpose of the Study:
- To demonstrate that high-permittivity materials (HPM) integrated with head-sized coil arrays can significantly improve brain-wide SNR.
- To evaluate the efficacy of an HPM helmet in enhancing both transmit efficiency and receive-side SNR.
Main Methods:
- Numerical simulations were performed to design an HPM helmet for 8- and 28-channel receive arrays.
- Two identical 30-channel head coils were constructed: one with a prototype HPM helmet and one with a low-permittivity shell.
- In vivo experiments measured excitation flip angle and SNR using an 8-channel dipole array for excitation.
Main Results:
- Simulations predicted up to 65% improvement in transmit efficiency and 47% in receive-side SNR.
- Experimental results showed a ~56% increase in transmit efficiency at the brain's center.
- Receive-side SNR improved by approximately 21% on average across orthogonal planes, including the brain's center.
Conclusions:
- High-permittivity materials (HPM) can enhance transmit efficiency and receive-side SNR throughout the brain when used with head-sized receive arrays.
- This approach offers a novel method to improve SNR in the entire brain, overcoming limitations of local HPM applications and improving SNR in difficult-to-reach central areas.
