Journal Article

Monopole antenna array design for 3 T and 7 T magnetic resonance imaging

Reutens, David C., Kausar, A. S. M. Zahid, Vegh, Viktor, Weber, Ewald

2019

Overview

Ultra-high field magnetic resonance imaging poses a number of challenges for robust radio frequency coil designs. A monopole antenna array can potentially overcome key limitations of birdcage coil designs and may provide a useful radio frequency coil for brain imaging. Four, 8 and 12 element monopole antenna arrays were simulated using 3 T and 7T magnetic resonance imaging frequencies. For comparison, 4, 8 and 12 element birdcage coils were also simulated. Coil performance was evaluated and compared and the impact of shielding was assessed. A 4 element monopole antenna array was fabricated and bench tested. Comparison of the 4, 8 and 12 element designs suggest that the monopole antenna array leads to better field properties than the birdcage coil in all configurations studied: unloaded, loaded with saline and loaded using a head phantom. Improvements in field properties and homogeneity were evident at both field strengths, implying that the monopole antenna array has potential for head imaging. The monopole antenna array also appears to be more efficient than the comparable birdcage coil design. Additionally, the former is scalable via the addition of more elements whereas our results suggest that this is not the case for the latter. Bench testing results show that the monopole antenna array is well matched with the transmission line, and mutual coupling between elements is sufficiently low. We found the monopole antenna array generated a larger field intensity than the birdcage coil design, whilst also producing a more useful magnetic resonance imaging field as measured by radio frequency field homogeneity. Our study suggests that magnetic resonance imaging of the brain can likely benefit from the use of radio frequency monopole antenna arrays.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Antenna arrays / Antenna design / Antennas (Electronics) / Arrays / Biology and Life Sciences / Brain / Brain - diagnostic imaging / Brain Mapping - instrumentation / Brain Mapping - methods / Comparative analysis / Computer Simulation / Design / Diagnostic imaging / Efficiency / Engineering / Engineering and Technology / Equipment Design / Head - diagnostic imaging / Homogeneity / Humans / Magnetic resonance / Magnetic resonance imaging / Magnetic Resonance Imaging - instrumentation / Magnetic Resonance Imaging - methods / Magnetic shielding / Medical imaging / Medicine / Medicine and Health Sciences / Monopole antennas / Monopoles / Mutual coupling / Neuroimaging / NMR / Nuclear magnetic resonance / Phantoms, Imaging / Physical Sciences / Protective Devices / Radio frequency / Radio Waves / Research and Analysis Methods / Resonance / Scanners / Signal-To-Noise Ratio / Superconductivity / Transmission lines