The purpose of this proposal is to enhance and evaluate methods for functional Magnetic Resonance Imaging (fMRI) that are capable of whole brain coverage at high temporal and spatial resolution (20-30 slices per second). This project has been motivated by needed, and sometimes conflicting, enhancements to the methodology used during fMRI studies: 1) faster imaging, which is necessary to resolve subtle features in the fMRI time-course and to reduce artifacts from physiological processes and head movement, 2) larger volume of coverage, which is needed to image distributed processing areas and/or to increase the accuracy of the movement coverage, which is needed to image distributed processing areas and/or to increase the accuracy of the movement corrections, 3) higher spatial resolution, which is required to reduce partial volume effects and susceptibility dephasing at air/tissue boundaries. With current fMRI technology, investigators must sacrifice one or more of these features during the design and execution of their studies. As part of the proposed research plan, methods for rapid, whole brain, acquisition and reconstruction at high temporal and spatial resolution will be developed, optimized and evaluated with respect to reliability of activation and sensitivity to vascular, movement, and magnetic susceptibility artifacts. These methods include efficient implementations of Echo Volumar Imaging (EVI) and a new acquisition method called Simultaneous Multi-slice Acquisition using Rosette Trajectories (SMART). We will also conduct studies to characterize the operational parameters for image acquisition techniques capable of extracting subtle temporal dynamics from fMRI data. Success in this project will lead to valuable new imaging methods capable of imaging large volumes of the brain in a manner that is robust to artifacts. It will dramatically aid in the study of patients and pediatric populations in which head movement is a hindrance. It will allow development of activation paradigms that can take advantage of fMRI time-course information and will allow the analysis of fMRI responses to individual behavioral trials over the entire brain. Finally, it will provide new rapid imaging methods that may be useful for other applications of high-speed, dynamic MRI.
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