Introduction of the snake antenna array: Geometry optimization of a sinusoidal dipole antenna for 10.5T body imaging with lower peak SAR. Issue 5 (5th May 2020)

• Record Type: Journal Article
• Authors: Steensma, Bart; van de Moortele, Pierre‐Francois; Ertürk, Arcan; Grant, Andrea; Adriany, Gregor; Luijten, Peter; Klomp, Dennis; van den Berg, Nico; Metzger, Gregory; Raaijmakers, Alexander
• Is Part Of: Magnetic resonance in medicine. Volume 84:Issue 5(2020)
• Page Start: 2885
• Page End: 2896
• Publication Date: 2020-05-05
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.28297
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : 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 B 1 + ‐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 B 1 + ‐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.