Improved dynamic MRI of the wrist and heart at 0.55 T enabled by rapid 3D printed flexible coils.

Dynamic MRI at low field is limited by reduced signal-to-noise ratio (SNR) and additional losses imposed by accelerated acquisitions required for high temporal resolution. Flexible, anatomically conformal coils can recover SNR by maintaining proximity during motion, but lower conductor conductivity introduces resistive losses, requiring careful material optimization. We demonstrate high-quality dynamic imaging at 0.55 T using coils fabricated via two rapid, low-cost digital methods: direct-ink-write silver printing and screen printing of copper-doped EGaIn. Four-element wrist arrays were fabricated in 8 minutes per element at approximately $30 in consumable materials. In three subjects, both arrays achieved up to 4 × higher contrast and 5 × greater sharpness than a commercial coil during dynamic wrist imaging. To demonstrate generalizability, a seven-element silver-ink cardiac array produced cine images comparable to a commercial coil. These results establish digitally fabricated flexible coils as a scalable and accessible solution for dynamic musculoskeletal and cardiac MRI at low field.