A Single, Universal, and Digitally Programmable RF System Enables MRI of Any Nucleus

About This Grant

Abstract There are 118 known elements. Nearly all of them have nuclear magnetic resonance (NMR) active isotopes and at least 39 different nuclei from 33 elements have been used in biological and biomedical NMR studies. Despite the availability of dozens of NMR active isotopes (2H, 7Li, 13C, 17O, 23Na, 31P, 35Cl, 39K, etc.), most of today’s MRI is based on one nucleus – 1H. Since its inception in the 1970s, MRI technology has made immense gains in SNR with hyperpolarization, high and ultra-high field magnets, anatomy-conforming receiver coils, improved reconstruction, and other techniques. With these SNR gains, the imaging of nuclei other than 1H, or X- nuclei, has become more clinically feasible, inspiring a variety of studies capitalizing on the essentially perfect nuclear specificity of NMR/MRI to gain information not possible with 1H alone. Notably, hyperpolarized media and deuterium imaging have made significant gains recently. These and further studies, however, are still held back by technical challenges and the low availability and high cost of the necessary tools. To overcome these bottlenecks, we aim to develop an RF system, called the ADAPT PRO system, that can be digitally programmed on the fly to image any nucleus of interest independently or simultaneously. The system will bring out the full potential of all NMR active nuclei, significantly enhancing disease knowledge, diagnoses, and treatment evaluations. X-nuclei benefits have already been shown for cancer, osteoarthritis, Alzheimer’s, and many more. The system can be mass manufactured on assembly lines without the need of highly trained coil engineers. As such, it can be produced at orders-of-magnitude lower cost, thus facilitating the clinical translation and democratization of X-nuclei spectroscopy and MRI in general. Our innovative approaches have independent transmit and receive components. The transmit side integrates high-frequency, high-power switches into the coil structure, merging the RF amplifier and coil into a single programmable device that converts DC power to any RF frequency of interest. The receive side uses high-frequency, low-noise variable capacitors (varactors) driven to convert received MRI signals from an untuned coil to the ~500 MHz range, which are then amplified by a resonant ~500 MHz circuit. These advances promise to bring MRI coils to the digital age, enabling vastly more capabilities via programmability. Any-nucleus imaging is one new capability, and more potential capabilities include magnetic field shimming for undistorted data, improving quantification by reducing coil loading effects by the patient, and being reused between scanners of different field strengths, including emerging low-field portable scanners. Our proposed work has the potential to solve a wide range of important problems all at once.