Magnetic Resonance Imaging can now detect cells that are labeled with contrast agents such as superparamagnetic iron oxide (SPIO). Quantitative monitoring, which is desirable for evaluating cellular therapies, remains challenging. In this work, an MRI technique called TurboSPI is implemented for quantitative cellular imaging. TurboSPI acquires maps of the relaxation rate R2', which is directly related to SPIO concentration. Quantification of R2' is demonstrated using micron-sized iron oxide particles and SPIO-labeled cells. To explain experimental results that deviated from predicted behavior, an extended analytical description of MRI signal relaxation near SPIO was developed. This model compares well to Monte Carlo simulations and experimental data, and may allow improved quantification. The slow imaging speed of TurboSPI is overcome using a signal processing technique called compressed sensing to reconstruct undersampled data, enabling in vivo animal imaging with TurboSPI. Such images demonstrate detection of iron with improved specificity and good potential for quantification.

Computed Tomography (CT) is often used for building 3D biomechanical models of human anatomy. This method exposes the subject to a significant x-ray dose and provides limited soft-tissue contrast. Magnetic Resonance Imaging (MRI) is a potential alternative to CT for this application, as MRI offers significantly better soft-tissue contrast and does not expose the subject to ionizing radiation. However, MRI requires long scan times to achieve 3D images at sufficient resolution, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). These long scan times can make subject motion a problem. This thesis describes my work to reduce scan time while achieving sufficient resolution, SNR, and CNR for 3D biomechanical modeling of (1) the human larynx, and (2) the human hip. I focused on two important strategies for reducing scan time and improving SNR and CNR: the design of RF coils optimized to detect MRI signals from the anatomy of interest, and the determination of MRI relaxation properties of the tissues being imaged (allowing optimization of imaging parameters to improve CNR between tissues). Work on the larynx was done in collaboration with the Thomson group in Mechanical Engineering at BYU. To produce a high-resolution 3D image of the larynx, a 2-channel phased array was constructed. Eight different coil element designs were analyzed for use in the array, and one chosen that provided the highest Q-ratio while still meeting the mechanical constraints of the problem. The phased array was tested by imaging a pig larynx, a good substitute for the human larynx. Excellent image quality was achieved and MR relaxometry was then performed on tissues in the larynx. The work on the hip was done in collaboration with the Anderson group in orthopedics at the University of Utah, who are building models of femoral acetabular impingement (FAI). Accurate imaging of hip cartilage requires injection of fluid into the hip joint capsule while in traction. To optimize contrast, MR relaxometry measurements were performed on saline, isovue, and lidocaine solutions (all typically injected into the hip). Our analysis showed that these substances actually should not be used for MR imaging of the hip, and alternate strategies should be explored as a result.