INVESTIGATION OF T1 CONTRAST AND DTI AT HIGH FIELDS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。要充分利用在我们的资源中开发的高场和射频开发，还需要优化成像序列，才能充分实现增益。在这些方面，在我们合作伙伴的应用需求的推动下，我们需要在我们的系统上开发、测试和应用T1对比度和DTI序列。随着场强的增加，组织中的T1趋于发散，从而更难获得对比度。我们可以在高场下很好地提高信噪比，但如果没有对比度，图像在许多应用中的实用性就会受到影响。例如，在一项研究中，一位检查兔视神经炎的用户在11T比4.7T获得了更好的信噪比，但对比度更差，导致他更喜欢4.7T。已经证明，在高达8特斯拉的场中，MDEFT序列可以缓解这种情况。因此，我们已经开始执行4.7、11和17.6T的MDEFT序列。在对幻影进行了系统的评估之后，体内研究正在开始。弥散张量成像是一种较新的技术，在神经组织中有很大的应用前景。对于准确的光纤跟踪，信噪比是最重要的，因此使用高场和我们的射频线圈开发是至关重要的。此外，还需要对DTI计算和光纤轨迹映射进行准确的数据处理。因此，我们正在与计算机科学家和图像处理和分析专家合作，研究数据分析的方法。这些结果有助于指导磁共振技术和数据采集方面所需的发展。

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.