Measurement of T1 in the Vessel Wall Using MRI

This thesis presents a high-resolution volumetric technique to measure the longitudinal relaxation time T1 in the vessel wall using MRI. The method of Variable Flip Angles (VFA) was applied using a new strategy for flip angle selection that allows measurement of T1 with high accuracy (< 10% mean error) and precision (T1-to-noise ratio > 10) over the wide range of anticipated values (300-3000ms) in the vessel wall. This strategy was validated in simulation, phantom and volunteer spinal cord experiments. Initial validation of vessel wall T1 measurements was performed in ex-vivo thoracic aorta samples from cholesterol-fed rabbits. For in-vivo vessel wall T1 mapping, the technique was augmented with spatial saturation bands for flow suppression and applied to the carotid arteries of three volunteers. Preliminary results from volunteers suggest that this approach may be useful in characterizing T1 changes associated with high-risk atherosclerotic disease.