This application is an amended version of 1 RO1 HL56394, previously titled """"""""Improved Methods for Magnetic Resonance Angiography."""""""" The original application had proposed the broad development of several new methods for noninvasive magnetic resonance angiography (MRA) of carotid, renal, and peripheral vessels. In this resubmission, now titled """"""""Improved MR Peripheral Angiography,"""""""" the research plan focuses on the development, implementation, and evaluation of these MRA methods in a specific region-the lower extremities. The emphasis of this investigation will be on two novel MRA methods: 1) a flow-independent angiographic method that is well-suited for producing high-contrast vessel images in regions of slow flow, and 2) a modified version of two-dimensional time-of-flight angiography that uses a radial-line k- space trajectory to reduce pulsatility artifacts and achieve faster imaging. These new methods address the problems of flow artifacts, difficulties with slow flow, excessive imaging time, and inadequate spatial resolution which have limited the effectiveness of conventional MRA methods. Preliminary clinical results with these new methods amply demonstrate their substantial potential. A period of technical development and optimization will be followed by a comparative study of our MRA methods with conventional MRA and x-ray contrast angiography in patients with peripheral arterial disease. These new methods promise to provide improved detection and characterization of arteriosclerotic disease in the lower extremities.
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