Investigating Minimally Invasive Stressors for Functional MRI of the Kidneys

Abstract

<p>Chronic kidney disease (CKD) has an annual mortality rate of 22% and can cause secondary complications including hypertension, anemia, secondary hyperparathyroidism, and malnutrition. Currently, clinical diagnosis and evaluation of CKD involves blood and urine testing and biopsy. MRI is not currently used to image CKD, but there is an interest in developing MRI techniques to test kidney function. Usually, renal functional MRI refers to single images reflecting tissue oxygenation. Using time series information may offer additional information about changes in kidneys as a result of disease. In this thesis, blood oxygen level-dependent (BOLD) MRI and diffusion weighted imaging (DWI) were used to investigate the effects of breath holding and water loading on kidneys. First, BOLD MRI was used to measure effects of breath holding on BOLD signal intensity. DWI and fractal analysis were used to measure changes in diffusion, perfusion and microcirculation shortly after water loading. Breath holding results showed no effect on temporal BOLD signal intensity in young, healthy subjects. A significant decrease in signal intensity was measured in the kidney of a single subject with impaired renal function. Although the renal BOLD signal was found to have fractal characteristics, no changes were measured using this technique between pre- and post-water loading scans during the time period examined. Because the signal appears to behave fractally, this technique may be a good candidate for similar kidney function studies in the future. DWI also remained unchanged as a result of water loading during the post-water loading time period examined.</p>