Evaluation of a Flexible 8-Channel Coaxial Monopole Array for Knee Bone Marrow ASL Imaging at 7T

Motivation: To develop advanced parallel transmit coils to address the specific needs of knee bone marrow ASL imaging at 7T to improve perfusion SNR and imaging efficiency. Goal(s): To evaluate the performance of alternative knee coil designs in terms of B1+ coverage and RF efficiency. Approach: Fabricate and compare, both in electromagnetic simulation and experimentally, multi-channel transmit knee coil designs, including an 8-channel fractionated dipole array, and an 8-channel coaxial monopole array for knee ASL imaging studies. Results: Among the compared knee coils, the flexible 8-channel monopole array provided the largest B1+ coverage in z-direction, promising to overcome limitations found with other coils. Impact: ASL imaging of the knee is critical for scientific research and clinical studies. Developing better pTx coils will improve the quality, reliability, and efficiency of knee ASL imaging at ultra-high fields.