Reducing the Size and Cost of MRI by Using a Zero-He Moderate-Field MRI Magnet Integrated with a Cryocooled RF Coil

Abstract:This application proposes to demonstrate that the more economic cryogen-free magnets operating at moderate fields of 0.5T-1T, and integrated with cryocooled RF coils, can produce signal to noise ratios (SNR) that are potentially comparable to those of 1.5 T MRI scanners with conventional RF coils. This project paves the way towards high-performance, smaller size, and lower cost MRI scanners suited to the emerging interventional and point-of-care applications. It is well established that reducing the RF coil resistance by cooling is advantageous for either small coils or low fields. Because the required scan time decreases in proportion to the square of SNR, even modest improvements in SNR are highly advantageous, especially in interventional and point-of-care situations. The first Aim of the Phase I effort is to demonstrate the feasibility of obtaining significantly higher SNR by conduction-cooling of RF receive coils, and establish the tradeoffs between field strength, magnet size (cost), and SNR gained by cryocooling of the RF receive coil. The second Aim of Phase I is to use results of this tradeoff study to design a practical cryogen-free magnet for head-MRI that includes an integrated cryocooled RF receive coil that will be built in Phase II of this work. The addition of cryocooled RF receive coils (higher SNR) to the magnet is provided at a small incremental cost to the magnet system. SSI, the applicant, has a proven record in the development of advanced cryogen-free MRI magnets under SBIR funding, and several international medical device companies have adopted (licensed) SSI’s MRI cryogen-free magnet technology.Project Summary (Narrative)At the heart of the proposed innovative scanner will be a moderate-field (0.5-1 T) compact cryogen-free superconducting magnet that will be complimented with a conduction- cooled RF coil operating at about 50 K that is integrated within the cryogen-free superconducting magnet system using one and the same cryostat and cryocooler. The first Aim of the Phase I effort is to demonstrate the feasibility of obtaining significantly higher SNR by conduction-cooling of RF receive coils, and establish the tradeoffs between field strength, magnet size (cost), and SNR gained by cryocooling of the RF receive coil. The second Aim of Phase I is to use the result of the tradeoff study to design a practical cryogen-free magnet for head-MRI that includes an integrated cryocooled RF receive coil that will be built in Phase II of the program.