High-Tc SQUID-based ultra-low field MRI in unshielded environments

A high-performance MRI based on high-Tc SQUID and flux coupling at ultralow magnetic fields is reported in this work. The technique of NMR/MRI was optimized to study MRI of water phantoms and fingers. An SNR of 62 in image contrast was achieved for a water column of 200 μL at magnetic fields of 98 μT. The MRI showed high image contrast and demonstrated a spatial resolution of 2 mm for samples in magnetically unshielded environments. This resolution is comparable to the current state-of-the-art values (typically 2.0–3.0 mm) reported for SQUID-based ULF MRI systems. A clear image of fingers was demonstrated for the first time using high-Tc SQUIDs, which shows promise for biological or clinical applications.