We propose to develop the MRI physics acquisition techniques, the RF coil hardware, and the image reconstruction and signal processing methods to allow MR data to be performed during continuous motion of the patient table. Compared to the current, fixed, multi-station approach this offers improved time efficiency and eliminates brightness discontinuities between stations. Further, the use of real-time image reconstruction permits the table velocity to be adjusted in real time to match the observed transit of the contrast bolus on a patient-specific basis. New approaches for use of multiple coils in the lower extremities will permit two-fold reduced acquisition time. The long term goal of the project is to allow high resolution whole body MRI. The overall hypothesis of this project is that high resolution, arterial phase 30 contrast-enhanced MR angiography can be performed using real-time, patient-specific acquisition in conjunction with a continuously moving table. Specific projects to be studied are: 1. MRI Data Acquisition During Continuous Table Motion. The specific technique for data acquisition and correction during continuous table motion will be developed. The tradeoffs between field of view, spatial and time resolution, and velocity will be studied. Phase encode orders will be optimized, and alteration of slab thickness and position during the scan will be studied. Correction algorithms will be developed for magnetic field inhomogeneities and gradient non-linearities. 2. Dual-Coil Imaging. To exploit the non-contiguous fields of view in imaging the legs, an approach using two distinct transmit and receive coils will be developed. By isolating the response of each coil from the other, it is possible to collect data from each leg separately and simultaneously using the same pulse sequence. This is expected to provide a two-fold reduction in acquisition time for given resolution without the processing and noise amplification factors associated with SENSE. 3. Peripheral Runoff Study 3D MRA. The techniques developed in Projects 1 and 2 will be adapted to imaging the peripheral vasculature. Initially, tracking of a test bolus down the legs using a rapid 2D mode will guide the selection of table velocity during the high resolution 3D scan. Eventually, tracking will be done in real-time using fluoroscopic triggering, real-time determination of the bolus front, and dynamic velocity control.
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