High-density MRI coil arrays with integrated field monitoring systems for human connectome mapping.

Purpose: To develop and test two high-density MRI coil arrays with integrated field monitoring systems for enhanced diffusion imaging with strong diffusion-sensitizing gradients.

Methods: Two multichannel head coils were constructed for first- and second-generation 3T Connectome MRI scanners, incorporating 64 and 72 receive channels, respectively. The array coils were evaluated using RF bench-level metrics, including quality factor, tuning, matching, and coupling measurements. Imaging performance was comprehensively assessed through metrics such as SNR, $B_1^{+}$ efficiency, and inter-channel noise correlations, and compared with and without field camera integration. Parallel imaging capability was evaluated using geometry (g)-factors. The field camera performance was characterized by quantifying phase errors and field probe FID lifetimes. In vivo DWI acquisitions with high $b$ -values were performed to evaluate the system's ability to correct higher-order field perturbations.

Results: The developed arrays demonstrated up to 1.4-fold higher SNR and superior g-factor performance when compared to a commercially available 32-channel head coil. Integration of the field camera was achieved without compromising the performance of either system. In vivo imaging with concurrent field monitoring enabled accurate spatiotemporal field corrections, significantly reducing geometric distortions, blurring, and ghosting in high $b$ -value DWI.

Conclusion: The integration of high-density MRI arrays with field monitoring systems facilitated the capture and correction of spatiotemporal field perturbations during strong gradient activity, substantially enhancing image quality and diffusion parameter mapping quality. These advancements provide a robust platform for exploring the structural intricacies of the human connectome.