Project Summary/Abstract This S10 High-End Instrumentation grant application from Washington University (WU) in St. Louis requests funds in partial support of the purchase of a Bruker 15.2-Tesla small-animal MRI scanner to replace a two- decades-old Agilent/Varian 11.74-Tesla pumped MRI. This 11.74-Tesla MRI consumes a significant amount of liquid helium (5500 liters annually with a cost of over $150,000), which is unsustainable given the worldwide helium supply shortage. Moreover, with Agilent/Varian's exit from the MR market, the 11.74-Tesla scanner’s outdated hardware and software no longer meet the current and future needs of pre-clinical MRI research. The requested ultra-high field Bruker 15.2-Tesla Small-Animal MRI Scanner has state-of-the-art RF coils, gradient systems, and an extensive MR pulse sequence library to perform most modern MRI experiments in a preclinical setting. Its ultra-high field strength will provide a 2.6-fold increase in signal-to-noise ratio (SNR) compared to the 9.4T MRI, our only modern preclinical MRI system. In conjunction with its high-performance gradients (1.5 times stronger, almost 2 times higher slew rate than our 9.4T system), this gain can be leveraged to provide increased spatial resolution for ultra-fine anatomical definition, more accurate voxel-wise estimation of signal amplitude, increased blood oxygenation level-dependent (BOLD) contrast in functional MRI, and sensitivity to susceptibility weighted imaging and iron nanoparticles. This SNR gain is especially crucial for X- nucleus MR. Hydrogen and X-nucleus MR spectroscopy further benefits from increased spectral dispersion at a higher field. Of equal importance, advances in magnet technology allow the new 15.2-Tesla magnet to consume only ~12% as much liquid helium as the 11.74-Tesla system being replaced, thereby improving the sustainability of our preclinical imaging program. The requested Bruker 15.2-Tesla scanner will be managed by the Mallinckrodt Institute of Radiology’s (MIR) Small-Animal MR Facility. The Facility is service-oriented, highly collaborative, and well-integrated into the Washington University biomedical research community. The small animal MR facility is one of Washington University's most successfully shared research resources. In the five years preceding the pandemic, the Facility logged an average of approximately 5,900 scanner-usage hours annually from three small-animal MRI scanners. This scanner will help advance our already robust NIH-funded imaging research programs across many departments and centers in the School of Medicine and the McKelvey School of Engineering. University-wide support for this 15.2-Tesla small animal program has been provided by the Radiology Chair, Deans of the Schools of Medicine and Engineering, and Department Chairs and Center Directors of Major Users, with a total institutional commitment of $4,669,072.