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Magnetic resonance imaging of human articular cartilage of the knee in vivo [electronic resource]

Osteoarthritis (OA) is a degenerative joint disease that affects over 80% of the population of the U.S. by age 65. However, there is currently no disease-modifying treatment for OA. In order to develop and evaluate potential treatments, it is necessary to assess cartilage health over the course of the disease. Here, an MRI method is presented to obtain sodium images of tissue that pushes the current state of the art of sodium MRI and can provide new information about cartilage. The method presented here enables sodium imaging at high resolution and with lower noise levels than previously reported. This technique uses custom-made radio-frequency (RF) coils and a 3D-cones k-space trajectory and is well suited to imaging at high field strengths like 3 T and 7 T. A second novel method is presented for generating high-resolution, 3D T2 and ADC maps of the human knee in vivo. The maps are derived from diagnostic-quality morphological MR images. This method is based on a new variation of the 3D double echo steady-state (DESS) sequence and solves many of the current challenges of traditional imaging techniques. Finally, a third method is presented allowing independent excitation of two or more volumes with a short RF pulse for MRI. This method enables different volumes to be excited with different RF pulse parameters, including flip angle, slice profile or thickness, phase modulation, etc., increasing the flexibility of the excitation. In summary, the techniques presented here generate measurements of sodium, T2, and ADC in cartilage, all biomarkers of interest for this tissue. These measurements are either less noisy or more efficiently obtained than with previous methods. The methods presented in this dissertation also improve the efficiency of diagnostic image acquisition for the knee.