BIOMEDICAL ENGINEERING

The long term objective of this work is to improve methods to quickly and accurately diagnose human disease using magnetic resonance imaging (MRI) and provide resources that can be used for image guided therapy. Balanced steady state free precession (bSSFP or TrueFISP) is a leading rapid MR imaging pulse sequence with high signal-to-noise efficiency. However, the contrast is a mixture of T1 (longitudinal relaxation time) and T2 (transverse relaxation time) weighting and the signal from flowing blood is hyperintense. The objective of this work is to modify the magnetization preparation during the bSSFP sequence in order to extend the powerful bSSFP framework to important new applications. This presentation will describe progress toward two specific aims. The first aim is to develop and improve methods for removing T1 and isolating T2 contrast in bSSFP imaging. T2 contrast has proven to be an indispensable tool in the differentiation of many different diseases via MRI. A new method that simultaneously provides high spatial resolution and T2 contrast with fast scan time and low RF power deposition will be described. The second aim is to develop improved methods of attenuating the signal from flowing blood in bSSFP imaging. This is important for visualizing diseases involving the vessel wall (e.g. atherosclerosis), removing flow artifacts as well as providing accurate measurements of vessel sizes. New methods of providing black blood images with bSSFP contrast in stationary tissues without significantly increasing the repetition time will be described. Results from computer simulations as well as experimental testing in phantoms (stationary and moving) as well as asymptomatic human volunteers will be presented.