Dipolectric antenna for high‐field MRI

Abstract

Purpose To introduce the dipolectric antenna: a novel RF coil design for high‐field MRI using a combination of a dipole antenna with a loop‐coupled dielectric resonator antenna. Methods Simulations in human voxel model Duke involving 8‐, 16‐, and 38‐channel dipolectric antenna arrays for brain MRI were conducted. An 8‐channel dipolectric antenna for occipital lobe MRI at 7 T was designed and constructed. The array was built of four dielectric resonator antennas (dielectric constant = 1070) and four segmented dipole antennas. In vivo MRI experiments were conducted in one subject, and the SNR performance was benchmarked against a commercial 32‐channel head coil. Results A 38‐channel dipolectric antenna array provided the highest whole‐brain SNR (up to a 2.3‐fold SNR gain in the center of the Duke's head vs. an 8‐channel dipolectric antenna array). Dipolectric antenna arrays driven in dipole‐only mode (with dielectric resonators used as receive‐only) yielded the highest transmit performance. The constructed 8‐channel dipolectric antenna array provided up to threefold higher in vivo peripheral SNR when compared with a 32‐channel commercial head coil. Conclusion Dipolectric antenna can be considered a promising approach to enhance SNR in human brain MRI at 7 T. This strategy can be used to develop novel multi‐channel arrays for different high‐field MRI applications.