Modified Elliptical Centric View Orders for Improved Real-Time MRA

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The broad, long-term objective of this work is to develop novel, time-efficient methods for MR data acquisition and corresponding real-time signal processing techniques to allow formation of MR images which portray the cardiovascular system with high spatial resolution. This is significant due to the high incidence of cardiovascular disease. Specific aims to be studied in this work are: 1. Modified Elliptical Centric (EC) Acquisition Techniques. The EC view order will be combined with projection reconstruction (PR) k-space sampling to exploit the intrinsic advantages of both approaches. Variants of the EC-PR technique will be developed to provide: (i) improved resolution for given time using 2D homodyne (HD) reconstruction; (ii)time-resolved studies with frame rates as high as 2 Hz; (iii) compatibility with parallel imaging methods such as as SENSE for four-fold reduction in scan time; and (iv)compatibility with a combination of SENSE and HD reconstruction for six-fold scan time reduction for given resolution. The new methods will be applied to contrast-enhanced as well as non-contrast-enhanced MRA studies. 2. Real-Time Bolus Detection and Tracking. Means will be developed to detect and track contrast bolus transit in real time in a totally automated way as it moves through the vasculature over an extended field of view. This information will allow the generation of patient-specific bolus velocity profiles which can guide the MR angiographic pulse sequence and control table velocity and optimize spatial resolution on a patient- specific basis. 3. The Comprehensive Neurovascular Examination. The new acquisition and real-time computation techniques of Aims 1 and 2 will be integrated to provide a comprehensive angiogram of the aortic arch and great vessels, the carotid bifurcations, the intracranial arteries, and the draining veins of the brain following a single injection of contrast. Modest table motion during the exam will permit imaging of the extended FOV.