INVESTIGATION OF T1 CONTRAST AND DTI AT HIGH FIELDS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。如果要充分利用我们资源中开发的高场和射频开发，还需要优化成像序列。在这些方面，在合作者应用需求的驱动下，我们需要在我们的系统上开发、测试和应用T1对比和DTI序列。随着场强的增加，组织中的T1趋于发散，使对比更难获得。我们可以很好地提高高场的信噪比，但如果没有对比度，许多应用的图像效用就会受到损害。例如，在一项研究中，一个用户在检查兔子的视神经炎时，11T比4.7T得到更好的信噪比，但对比度更差，导致他更喜欢4.7T。研究表明，MDEFT序列可以在高达8特斯拉的电场下缓解这种情况。因此，我们已经开始在4.7、11和17.6T处实现MDEFT序列。在对幻影进行系统评估之后，体内研究开始了。DTI是一种相对较新的技术，在神经组织中有很大的应用前景。对于精确的光纤跟踪，信噪比是至关重要的，因此使用高场和我们的射频线圈的发展是至关重要的。与此相结合的是DTI计算和光纤轨迹映射需要精确的数据处理。因此，我们正在与图像处理和分析方面的计算机科学家合作，研究数据分析的方法。这些结果有助于指导核磁共振技术和数据采集方面的必要发展。

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.