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。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 神经系统疾病的早期诊断通常有助于疾病症状的治疗。除其他因素外，铁积累与几种神经疾病有关(Sehga等人。2005)。磁化率图像的差异对含铁的组织特别敏感。在核磁共振中，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，并生成实现标准震级图像所没有的对比度形式的图像。2005年，Sehga等人提出，磁化率成像速度更快，在高场强下产生更好的信噪比。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进。 该项目的具体目标是检查和描述： 1)灌注固定对敏感性图像的影响，注意到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关系。 3)T2*衰减，通过一系列改变TE的扫描，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)收集小鼠大脑的相图和磁化率图像。将在以下3种情况下对小鼠的大脑进行扫描： 1)在7T的活体内，TE H12ms，TRH100ms，αH20度，平均离线刺激足以达到与9T的条件2相似的SNR。 2)1T、2T、7T、9T注入生理盐水。 3)在1T、2T、7T和9T，TE H7ms，TRH100ms，Alpha H90度，NEX=2下用Gd(ProHance)灌流 对于22 mm x 11 mm x 11 mm的3D各向同性矩形图像，7T和9T扫描的扫描分辨率将为256 x 128 x 128。1T和2T的分辨率为128x x。 在活体扫描后，希望但不是必须的，对在上述条件(2)和(3)中存活的小鼠的大脑进行灌流。如果这些动物由于某种原因不适合灌流，那么将需要额外的小鼠进行灌流研究。

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.