SBIR-STTR Award

The investigators propose to test the feasibility of developing efficient, actively switched radiofrequency transmit and receive coils based on transverse electromagnetic (waveguide) principles for use in magnetic resonance imaging at 3 Tesla and above, as further described by their abstract: "The investigators plan to prove the feasibility of an efficient homogeneous transmit coil for human NMR studies at high field strengths (3T-4T). Such a coil will be unique in high field human applications. Significantly this homogenous transmit coil for human heads and bodies will facilitate the extension of the present 1.5T clinical MR transmit and receive imaging methods to the growing number (now 35), of 3T and 4T systems now operating or being delivered world wide. These favored transmit and receive imaging methods make use of a large transmit (body) coil, paired with a local surface coil or a phased array coil receiver. The large transmit coil is used to generate a homogeneous B1 field. The local surface coil or phased array then receives an NMR signal response with a high signal-to-noise (SNR) ratio from a localized region of interest (ROI). These independent transmit and receive coils must be actively decoupled from each other during transmit-receive operation. This decoupling requires both transmit and receive channel switching with a TR switch, and alternate transmit and receive coil detuning circuit. The overall goal of this project is therefore to develop, build, and test an actively switched and detuned RF transmit coil for efficient operation at 3T to 4T. This RF coil system consists of 5 functional components; the development of each component will be a Specific Aim. The demonstration of feasibility will be to prove that each of the coil system components meet their respective design specifications, followed by the successful testing of the assembled sum of these components in RF transmit coil system. In Phase I, this high field transmit coil system will be developed for human head imaging. In Phase II, this coil will be scaled for human body imaging."Proposed Commercial Application:3T and 4T Head and Body Coils for the MRI industry.

Thesaurus Terms:
biomedical equipment development, electromagnetic radiation, magnetic resonance imaging, nuclear magnetic resonance spectroscopy, radiation detector bioengineering /biomedical engineering, bioimaging /biomedical imaging, human subject, swineNATIONAL CENTER FOR RESEARCH RESOURCES

In this Phase II STTR project, the investigators plan to extend their successful Phase I feasibility demonstration to the development and manufacture of an RF body coil plus phased array receive system for use in high field clinical and research MRI systems. In Phase I, the feasibility of a large homogeneous transmit coil based on the TEM design was proven, published, and patented (pending). The first actively detuned TEM volume coil was developed together with receiver coils for neuroimaging applications in the accelerating number of high field (3T +) MRI systems delivered without body coils. This actively detuned TEM head coil was also developed as a first step toward a body coil, the goal of this Phase II grant. Why is a body coil needed for high field NMR? The option of body coil transmission for homogeneous excitation and surface coil or phased array reception for highest SNR is favored in clinical imaging at 1 .5T. This option is not yet generally available for the increasing number of systems operating at fields higher than 1 .5T. While manufacturers are currently developing body coils, mostly by the birdcage design for 3T, the short coil lengths, limited homogeneous field of views, 25kW-35kW power amplifier requirements, and consequentially curtailed pulse protocol options indicate that an efficient or otherwise optimal body coil design has not yet been found for 3T. For 4T and above, there are no current options for true, whole body imaging. A high field body coil together with dedicated receiver coils are needed to increase the MRI protocol options, signal to noise, and spectral resolution for a multitude of diagnostic and research applications. High field NMR has great potential as a tool for imaging and spectroscopy based research and diagnosis of neurological disorders, cardiovascular diseases, and cancer. The goal of this proposal, the provision of a body coil and dedicated receivers for the highest magnetic field strengths, will bring the fullest benefit of high field NMR to the study of health and disease in the human body.