GRADIENT ECHO PHASE AND SUSCEPTIBILITY IMAGING OF THE MOUSE BRAIN

这个子项目是利用资源的许多研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 神经系统疾病的早期诊断通常有助于疾病症状的治疗。 除其他外，铁积累与几种神经系统疾病有关（Sehgal et al. 2005）。磁化率图像的差异对含铁组织特别敏感。 在核MR中，磁化率成像利用这些磁化率差异从梯度回波序列扫描中提取相位信息，并生成实现标准幅度图像中未发现的对比度形式的图像。 2005年，Sehgal等人提出，磁化率成像将更快，并在更高的场强下产生更好的SNR。 表征不同场强下的磁化率差异将允许量化增加用于磁化率成像的场强所带来的改善。 该项目的具体目标是审查和确定： 1)灌注固定对敏感性图像的影响，注意灌注后体内和体外扫描的差异。 2)磁化率图像中显示的任何场强依赖性。 3)T2* 衰减通过采取一系列扫描变化TE，特别注意非指数衰减及其与相位的关系，使用组合的幅度和相位图像。 我将使用梯度回波序列（GPSW）收集小鼠大脑的相位和磁化率图像。 将在以下3种条件下扫描小鼠大脑： 1)在7 T下的体内，TE H 12 ms，TR H 100 ms，α H 20度，离线平均足够的激励，以达到与9 T下条件2相似的SNR。 2)在1 T、2 T、7 T和9 T下用生理盐水灌注。 3)在1 T、2 T、7 T和9 T下灌注钆（ProHance），TE H 7 ms，TR H 100 ms，α H 90度，NEX = 2 对于22 mm x 11 mm x 11 mm的3D各向同性矩形图像，7 T和9 T扫描的扫描分辨率将为256 x 128 x 128。 对于1 T和2 T，分辨率为128 x 64 x 64。 在体内扫描之后，期望但不是必须对存活用于上述条件（2）和（3）的小鼠的脑进行灌注。 如果这些动物由于某种原因不适合灌注，则需要额外的小鼠进行灌注研究。

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. The early diagnosis of a neurological disease often aids in the treatment of disease symptoms. Among other things, iron accumulation has been associated with several neurological diseases (Sehgal et al. 2005). Differences in magnetic susceptibility images are particularly sensitive to tissues containing iron. In nuclear MR, susceptibility imaging exploits these susceptibility differences to extract phase information from a gradient echo sequence scan and generate images that achieve a form of contrast not found in standard magnitude images. In 2005, it was suggested by Sehgal et al that susceptibility imaging will be faster and yield better SNR at higher field strengths. Characterizing magnetic susceptibility differences at different field strengths would allow the improvements from increasing the field strength used for susceptibility imaging to be quantified. The specific aims of this project are to examine and characterize: 1) the effect of perfusion fixations on susceptibility images, noting differences in scans performed in vivo and ex vivo following perfusion. 2) any field strength dependence exhibited in the susceptibility images. 3) T2* decay by taking a series of scans varying TE, paying particular attention to non-exponential decay and its relationship to phase using combined magnitude and phase images. I will gather phase and susceptibility images of the mouse brain using a gradient echo sequence (GPSW). The mice brains will be scanned under each of the following 3 conditions: 1) In vivo at 7T, with TE H12 ms, TR H 100 ms, alpha H 20 degrees, averaging enough excitations offline to arrive at a SNR similar to condition 2 at 9T. 2) Perfusion with saline at 1T, 2T, 7T, and 9T. 3) Perfusion with gadolinium (ProHance) at 1T, 2T, 7T, and 9T, TE H7ms, TR H100 ms, alpha H90 degrees, NEX = 2 Scan resolution for the 7T and 9T scans will be 256 x 128 x 128 for a 22mm x 11mm x 11mm, 3D isotropic rectangle image. For 1T and 2T, resolution will be 128 x 64 x 64. After the in vivo scans, it is desired, but not necessary, to perform perfusion on the brains of the mice that survive for use in conditions (2) and (3) above. If those animals are not suitable for perfusion for some reason, then additional mice will be required for the perfusion studies.