Advances In Neuroimaging Methods for 7 Tesla Human Brain Magnetic Resonance Imaging

7-Tesla (T) magnetic resonance imaging (MRI) is currently the highest-field MRI available for clinical use. It has better spatial resolution and sensitivity than lower-field MRI scanners. High resolution and increased sensitivity can mean shorter scan times, the ability to see small structures and changes in the brain that may not be visible on lower-field MRI scans, and higher temporal resolution for functional MRI (fMRI). 7T MRI has many clinical and research uses, especially for neuroimaging, in targeting neurological, neurodegenerative, and psychiatric conditions. However, it has yet to be widely used, even in centers with these systems. Several factors, such as cost, availability, technical limitations of ultra-high-field MRI (such as signal inhomogeneities and increased power deposition in the tissue), and the need for research and clinical applications, can explain the limited adoption. In this dissertation, we use the main strengths of 7T MRI, including its high signal-to-noise ratio, increased susceptibility, and contrast for blood oxygenation level-dependent (BOLD) fMRI and high resolution (on the order of hundreds of micrometers), to develop neuroimaging methods that take advantage of these strengths. This dissertation starts by reviewing state of the art in ultra-high-field neuroimaging for small vessel disease and late-life depression. Then, we present a novel approach to connecting microscopic white matter lesion histological characterization with white matter hyperintensities acquired with MRI. Finally, we show that fMRI resting-state functional connectivity may be a neuroimaging marker for sickle cell disease severity and accelerated aging