CEST IMAGING OF GLYCOGEN

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。 最近，我们提出了一种通过糖原的OH质子与水质子相互作用来进行核磁共振成像的方法，这种相互作用可以通过磁化转移来测量。简而言之，糖原分子中的可交换质子(OH)可以用正确的质子核磁共振频率选择性地辐射。由于与水质子的快速化学交换，这种自旋标记可以通过水线检测，因此可以通过常规的磁共振实验进行检测。与其他磁化传递实验一样，关键是比较在糖原的OH质子照射下的体水信号和相对于水共振的相反频率的体水信号。在这两个频率照射得到的归一化水信号强度之间的显著差异可以检测到糖原中的OH质子的交换。更复杂的方法也是可行的。例如，可以获得完整的Z谱，而不是使用两个频率中的最小值。Z谱的不对称性可以归因于可交换的OH基团。 糖原的非侵入性测量是描述体内代谢状态的一个组成部分。虽然许多研究报告了糖原的检测，但专注于其定量的报告有限。此外，7T全身扫描仪的扩大使用需要优化这一特定领域的糖原采集方案。我们将研究三种不同的7T糖原检测和定量方法：直接~(13)C MRS、糖化和直接质子MRS。所有研究均使用半径为13厘米的半圆柱形发射-接收表面线圈。该线圈在1H和13C两种情况下均以正交方式运行。

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. Recently we proposed a method for imaging glycogen by MRI through the interaction of the OH protons of glycogen with the water protons which can be measured using magnetization transfer. Briefly, the exchangeable protons (OH) in the glycogen molecule can be selectively irradiated with the correct proton NMR frequency. Because of the fast chemical exchange with water protons, this spin label can be detected through the water line, and hence through the conventional MRI experiment. Like other magnetization transfer experiments, the key is to compare the bulk water signal in the presence of irradiation of the OH protons of glycogen with the bulk water signal at the opposite frequency with respect to the water resonance. The exchange of the OH protons in glycogen can be detected as a significant difference between the normalized water signal intensities obtained by irradiating at these two frequencies. More sophisticated approaches are also feasible. For example, instead of using the minimum of two frequencies, a full Z-spectrum can be obtained. The asymmetry in the z spectrum can be attributed to exchangeable OH groups. Noninvasive measurement of glycogen is an integral part of profiling the metabolic state in vivo. While many studies have reported detection of glycogen, there are limited reports that have focused on its quantification. Furthermore, the expanded use of 7T whole body scanners requires optimization of the glycogen acquisition protocols for this particular field. We will investigate three different approaches for glycogen detection and quantification at 7T: direct 13C MRS, glycocest and direct proton MRS. A half-cylinder transmit-receive surface coil with radius of 13-cm was used for all studies. The coil runs in quadrature for both 1H and 13C.