Simulation guided design of a cryogenic probe for micrometer-scale in vivo MR imaging

The electromagnetic (EM) simulation guided design and operation of a receive-only liquid nitrogen (LN₂) cooled coil suitable for medical imaging on a 3-T whole body MR scanner is presented. This process is easier and more cost-effective than building a range of coils. The performance of the designed probe was evaluated by comparison of signal-to-noise ratio (SNR) with the same radio-frequency (RF) coil operating at room temperature (RT). The cryogenic coil achieved a twofold SNR gain for small animal medical imaging applications. For mouse brain imaging, a 100 μm resolution was achieved in an imaging time of 3.5 minutes with an SNR of 25-40, revealing fine anatomical details unseen at lower resolution in the same time. The observed SNR was in good agreement with the expected SNR gain correlated to the loaded quality (Q) factor of RF coils from EM simulations.