This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Much work has been done recently on imaging techniques that utilize chemical exchange of protons to make MR imaging sensitive to concentrations of proteins and their immediate environments. Spin-lattice relaxation in the rotating frame (T1?) is an imaging technique which is dependent on the exchange of protons but has yet to be applied to imaging specific metabolites based on their chemical exchange properties. There have been no studies to date using T1? for contrast in the chemical exchange of protons. T1? Chemical exchange effects vary quadratically with the static magnetic field. Therefore, T1? potentially offer higher sensitivity at higher fields in probing exchange mediated interactions in nuclear spin systems. This higher sensitivity of T1? MRI may enable detection of endogenous metabolites that possess a proton exchange site at low concentrations (~1 mM). Our hypothesis is that Tip based MRI will be less susceptible to line shape changes and provide higher sensitivity in detecting metabolites with exchangeable protons. The purpose of this subproject is to develop a sensitive and robust method to quantify the concentration of and metabolites exhibiting a chemical exchange of protons with water using T1?.
Study Aims : 1. To develop a method to that utilizes T1? MRI techniques that can be used to create image contrast and quantify metabolites with exchangeable protons. 2. To determine the effect that concentration, pH, static magnetic field, B1 field strength and saturation time have on the chemical exchange and subsequent T1? contrast 3. To demonstrate that our model can be reliably used to quantify the concentration of metabolites with exchangeable protons in animal models and humans.
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