INVESTIGATION OF T1 CONTRAST AND DTI AT HIGH FIELDS

该子项目是利用 NIH/NCRR 资助的中心拨款提供的资源的众多研究子项目之一。子项目和研究者 (PI) 可能已从另一个 NIH 来源获得主要资金，因此可以在其他 CRISP 条目中出现。列出的机构是中心的机构，不一定是研究者的机构。如果要充分实现收益，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，在我们合作者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 往往会发散，从而更难获得对比度。我们可以很好地提高更高视场的信噪比，但如果没有对比，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，一位检查兔子视神经炎的用户在 11T 下获得的信噪比比 4.7T 更好，但对比度较差，导致他更喜欢 4.7T。事实证明，MDEFT 序列可以在高达 8 特斯拉的磁场中缓解这种情况。因此，我们开始在 4.7、11 和 17.6T 上实施 MDEFT 序列。在对模型进行系统评估后，体内研究开始。 DTI 是一项相对较新的技术，对神经组织有很大的应用。对于精确的光纤跟踪，SNR 至关重要，因此高场的使用和我们的射频线圈开发至关重要。除此之外，还需要进行 DTI 计算和光纤轨迹测绘的精确数据处理。因此，我们正在与图像处理和分析专家的计算机科学家合作研究数据分析方法。这些结果有助于指导 MR 技术和数据采集所需的发展。

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.