INVESTIGATION OF T1 CONTRAST AND DTI AT HIGH FIELDS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Taking advantage of the high fields and rf developments developed in our Resource also requires optimization of imaging sequences if the gains are to be fully realized. In these regards, and driven by the application needs of our collaborators, we require the development, testing and application of T1 contrast and DTI sequences on our systems. As the field strength increases, T1 in tissues tend to diverge, making contrast harder to obtain. We may well improve the SNR at higher fields, but without contrast the utility of the images for many applications is compromised. For example, in one study a user examining optic neuritis in the rabbit get better SNR at 11T compared to 4.7T, but worse contrast, leading him to prefer the 4.7T. It has been shown that MDEFT sequences can alleviate this situation at fields of up to 8 Tesla. We have thus begun implementation of MDEFT sequences at 4.7, 11 and 17.6T. Following a systematic evaluation on phantoms, in vivo studies are beginning. DTI is a relatively new technique with great application to nervous tissue. For accurate fiber tracking, SNR is paramount, and hence the use of high fields and our rf coil developments is paramount. Coupled with this is the need for accurate data processing for DTI calculations and fiber track mapping. We are thus investigating methods for data analysis in collaboration with computer scientists expert in image processing and analysis. These results help guide the needed developments in MR techniques and data acquisition.