Improvements in Dynamic Contrast-Enhanced MR Angiography and Perfusion and Non-Contrast MRI

PRIMARY OBJECTIVE: I. To study how a variety of technological approaches in MRI can be used to provide improved performance contrast-enhanced MR imaging as used for angiography and perfusion as well as in MR image acquisition without the use of contrast material. OUTLINE: This is an observational study. Participants undergo a non-contrast MRI on study and may optionally undergo a second non-contrast MRI on study. Participants may also undergo blood sample collection on study.