Wide Field MR Microscopy using Integrated Gradient and RF Array Coils

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DESCRIPTION (provided by applicant): The objective of this EBRG proposal is to develop and demonstrate a new high resolution MR imaging technique, wide-field magnetic resonance microscopy (MRM). MR microscopy, defined by most as imaging with a resolution of 100 microns or less in any dimension, will become an invaluable tool as the future of medicine clearly moves towards the cellular level due to its ability to non-invasively probe in vivo and in vitro tissue with high-resolution while providing the many contrast mechanisms of MRI. While providing high resolution imaging of the tissue microenvironment, conventional MRM is limited to a very small field-of-view by the use of small radiofrequency coils designed to improve the signal-to-noise ratio, or, alternatively, by the time required to encode the MR image over a large field-of-view at high-resolutions. This work proposes a method for wide field MR microscopy. This technique combines parallel imaging and a unique phase correcting gradient channel to enable high resolution MRI over a large field-of-view at greatly reduced imaging times. The technological advancement to be developed in this project is an integrated gradient and RF array coil which provides the user a choice between extremely high-resolution imaging or extremely fast imaging (at reduced resolution). Both are enabled by using an array of 64 or more aligned receiver coils to parallelize the imaging process, reducing reliance on gradient-based phase encoding. High- speed digital receivers enable the field-of-view to be increased along the long-axis of the parallel coils, while parallel imaging increases the field-of-view in the opposite direction. A planar gradient coil will be optimized and an independent, fourth gradient channel integrated into the MR scanner to compensate for distant dependent phase shifts imparted by the receive coils which reduce signal strength in highly accelerated MR imaging. Finally, a team of collaborators interested in the potential of wide-field MR microscopy, including two experts in MR microscopy and three clinical scientists, will provide tissue samples of different types for testing and assessing the new method. If successful, this project will enable MR microscopy with wider perspective and higher speed than previously possible, extending it into a broader range of applications. Magnetic resonance microscopy extends the power of clinical magnetic resonance imaging to extremely high resolutions, potentially down to cellular resolution. The goal of this project is to develop a new technique, wide field MR microscopy, which combines parallel imaging with a unique phase correcting gradient to enable high resolution MRI over a large field of view at greatly reduced imaging times. This technique is enabled by a new probe design which will provide the ability to perform MR microscopy at either extremely high spatial resolution or extremely high temporal resolution over the same field-of-view.