Comparative Analysis of Simulated Signal-to-Noise Ratio in Loop and Sleeve Antennas at 10.5 Tesla for Human Head Imaging
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'Purpose: To explore the signal-to-noise ratio (SNR) of loops and sleeve antennas for human head imaging at 10.5 tesla. Materials and Methods: Simulated SNR maps were calculated using XFdtd with a resolution of 2 × 2 × 2 mm3. The 3D CAD renderings of the loop and sleeve antennas with single- , three- , and five-channels were evaluated. Each loop coil had dimensions of 35 × 50 mm2, and the length of the individual sleeves was 180 mm, with an additional 70 mm for the required coaxial sleeve balun. All SNR maps were calculated using MATLAB. These base elements were evaluated in three-loop configurations aligned in the z-direction and compared with the same number of sleeve antenna arrays spaced 15 mm apart to achieve similar coverage. This comparison was further extended to the five-channel case for both loops and sleeve antennas in arrangements that could achieve similar overall imaging coverage. Results: The single-sleeve antenna demonstrated a 17% higher SNR in close proximity to the conductor compared to a loop. A boost in SNR performance was also observed with three- and five-channel sleeve antennas with a close gap (15 mm) between the elements, as indicated. Substantial SNR improvements were mostly associated with the peripheral gains achievable with closely coupled sleeve antennas in a high-density array arrangement. Conclusion: The sleeve antenna concept supports high-density receiver antenna arrays. Due to the higher conductor density, it can result in a significant peripheral SNR gain.
Abstract
'Purpose: To explore the signal-to-noise ratio (SNR) of loops and sleeve antennas for human head imaging at 10.5 tesla. Materials and Methods: Simulated SNR maps were calculated using XFdtd with a resolution of 2 × 2 × 2 mm3. The 3D CAD renderings of the loop and sleeve antennas with single- , three- , and five-channels were evaluated. Each loop coil had dimensions of 35 × 50 mm2, and the length of the individual sleeves was 180 mm, with an additional 70 mm for the required coaxial sleeve balun. All SNR maps were calculated using MATLAB. These base elements were evaluated in three-loop configurations aligned in the z-direction and compared with the same number of sleeve antenna arrays spaced 15 mm apart to achieve similar coverage. This comparison was further extended to the five-channel case for both loops and sleeve antennas in arrangements that could achieve similar overall imaging coverage. Results: The single-sleeve antenna demonstrated a 17% higher SNR in close proximity to the conductor compared to a loop. A boost in SNR performance was also observed with three- and five-channel sleeve antennas with a close gap (15 mm) between the elements, as indicated. Substantial SNR improvements were mostly associated with the peripheral gains achievable with closely coupled sleeve antennas in a high-density array arrangement. Conclusion: The sleeve antenna concept supports high-density receiver antenna arrays. Due to the higher conductor density, it can result in a significant peripheral SNR gain.
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