CEST IMAGING OF GLYCOGEN CONTENT COMPARED TO IN VIVO GLYCOGENOLYSIS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 最近，我们提出了一种通过MRI成像糖原的方法，通过糖原的OH质子与水质子的相互作用，可以使用磁化转移测量。简而言之，糖原分子中的可交换质子（OH）可以用正确的质子NMR频率选择性地照射。 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到，因此可以通过传统的MRI实验检测到。与其他磁化转移实验一样，关键是将糖原的OH质子照射存在下的本体水信号与相对于水共振的相反频率下的本体水信号进行比较。糖原中OH质子的交换可以被检测为通过在这两个频率下照射获得的归一化水信号强度之间的显著差异。更复杂的方法也是可行的。 例如，代替使用两个频率中的最小值，可以获得全Z频谱。 z光谱中的不对称性可归因于可交换的OH基团。 我们在约翰霍普金斯的团队有能力在我们的3 T系统中独立进行这些研究。 然而，我们希望整合本RR中可用的2 H NMR方法，以便我们可以在巴尔的摩的磁体中测量患者的糖原分解，将样本运送到达拉斯，并通过CEST比较人类的肝糖原分解率与氘的肝糖原分解率。

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. 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. Our group at Johns Hopkins has the capability of performing these studies independently in our 3T system. However, we would like to integrate the 2H NMR methods available in this RR so we can measure glycogenolysis in our patients in our magnet in Baltimore, ship the samples to Dallas, and compare liver glycogenolytic rates in humans by CEST to liver glycogenolytic rates by deuterium.