Visualization and quantification of renal R2* changes during water diuresis

PURPOSE: To refine and evaluate methods for analysis of renal blood oxygenation level dependent (BOLD) MRI data. MATERIALS AND METHODS: Color R2* maps and regions-of-interest (ROIs) on the borderline between cortex and medulla were applied to renal BOLD MRI data of a group of 13 young female subjects. RESULTS: The distribution of R2* within the kidneys was heterogeneous and the response of human kidneys to water diuresis was patchy. R2* values at the cortico-medullary border region have a smaller variation than in wider cortical or medullary regions and are sensitive to physiological changes produced by water diuresis. CONCLUSION: These methods provide improved visualization of the regional distribution of R2* and its variations and more precise quantification of the changes in renal R2* produced by water diuresis.