Design and Construction of a Heteronuclear 1H and 31P Double Tuned Coil for Breast Imaging and Spectroscopy

Magnetic resonance imaging (MRI) is a noninvasive imaging modality that uses radio frequency (RF) energy to excite nuclei in the presence of a strong magnetic field and linear spatially encoding magnetic field gradients. Clinically, MRI takes advantage of the spin properties of hydrogen (1H) nuclei due to the high concentration and relative abundance in tissue water and fats. However, other nuclei having the quantum mechanical property of spin can also be probed. One of the most common is phosphorous (31P), which has 100% natural abundance and reasonable in vivo concentrations that are measurable at clinical MRI field strengths. Phosphorous measurements can provide an understanding of important metabolic pathways within tissues, which ultimately can help in better understanding disease and treatment. However, clinical MRIs do not routinely come with the ability to assess non-1H nuclei. Hence, hardware and pulse sequences need development, while considering the need to easily interface with standard clinical MRI hardware and protocols. This review describes the motivation for and development of MRI RF hardware designs for a human breast imaging system that can acquire 31P data from a clinically approved breast MR imaging and biopsy table.