TY - JOUR
T1 - Introduction of the snake antenna array
T2 - Geometry optimization of a sinusoidal dipole antenna for 10.5T body imaging with lower peak SAR
AU - Steensma, Bart
AU - van de Moortele, Pierre Francois
AU - Ertürk, Arcan
AU - Grant, Andrea
AU - Adriany, Gregor
AU - Luijten, Peter
AU - Klomp, Dennis
AU - van den Berg, Nico
AU - Metzger, Gregory
AU - Raaijmakers, Alexander
N1 - Publisher Copyright:
© 2020 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine
PY - 2020/11/1
Y1 - 2020/11/1
N2 - Purpose: To improve imaging performance for body MRI with a local transmit array at 10.5T, the geometry of a dipole antenna was optimized to achieve lower peak specific absorption rate (SAR) levels and a more uniform transmit profile. Methods: Electromagnetic simulations on a phantom were used to evaluate the SAR and (Formula presented.) -performance of different dipole antenna geometries. The best performing antenna (the snake antenna) was simulated on human models in a 12-channel array configuration for safety assessment and for comparison to a previous antenna design. This 12-channel array was constructed after which electromagnetic simulations were validated by (Formula presented.) -maps and temperature measurements. After obtaining approval by the Food and Drug Administration to scan with the snake antenna array, in vivo imaging was performed on 2 volunteers. Results: Simulation results on a phantom indicate a lower SAR and a higher transmit efficiency for the snake antenna compared to the fractionated dipole array. Similar results are found on a human body model: when comparing the trade-off between uniformity and peak SAR, the snake antenna performs better for all imaging targets. Simulations and measurements are in good agreement. Preliminary imaging result were acquired in 2 volunteers with the 12-channel snake antenna array. Conclusion: By optimizing the geometry of a dipole antenna, peak SAR levels were lowered while achieving a more uniform transmit field as demonstrated in simulations on a phantom and a human body model. The array was constructed, validated, and successfully used to image 2 individuals at 10.5T.
AB - Purpose: To improve imaging performance for body MRI with a local transmit array at 10.5T, the geometry of a dipole antenna was optimized to achieve lower peak specific absorption rate (SAR) levels and a more uniform transmit profile. Methods: Electromagnetic simulations on a phantom were used to evaluate the SAR and (Formula presented.) -performance of different dipole antenna geometries. The best performing antenna (the snake antenna) was simulated on human models in a 12-channel array configuration for safety assessment and for comparison to a previous antenna design. This 12-channel array was constructed after which electromagnetic simulations were validated by (Formula presented.) -maps and temperature measurements. After obtaining approval by the Food and Drug Administration to scan with the snake antenna array, in vivo imaging was performed on 2 volunteers. Results: Simulation results on a phantom indicate a lower SAR and a higher transmit efficiency for the snake antenna compared to the fractionated dipole array. Similar results are found on a human body model: when comparing the trade-off between uniformity and peak SAR, the snake antenna performs better for all imaging targets. Simulations and measurements are in good agreement. Preliminary imaging result were acquired in 2 volunteers with the 12-channel snake antenna array. Conclusion: By optimizing the geometry of a dipole antenna, peak SAR levels were lowered while achieving a more uniform transmit field as demonstrated in simulations on a phantom and a human body model. The array was constructed, validated, and successfully used to image 2 individuals at 10.5T.
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U2 - 10.1002/mrm.28297
DO - 10.1002/mrm.28297
M3 - Article
C2 - 32367560
AN - SCOPUS:85085099462
SN - 0740-3194
VL - 84
SP - 2885
EP - 2896
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 5
ER -