PDF(Pubmed)
Abstract：
Glycogen plays essential roles in glucose metabolism. Imaging glycogen in the liver, the major glycogen reservoir in the body, may shed new light on many metabolic disorders. 13C magnetic resonance spectroscopy (MRS) has become the mainstream method for monitoring glycogen in the body. However, the equipment of special hardware to standard clinical magnetic resonance imaging (MRI) scanners limits its clinical applications. Herein, we utilized endogenous glycogen as a T 2-based relaxation contrast agent for imaging glycogen metabolism in the liver in vivo. The in vitro results demonstrated that the transverse relaxation rate of glycogen strongly correlates with the concentration, pH, and field strength. Based on the Swift-Connick theory, we characterized the exchange property of glycogen and measured the exchange rate of glycogen as 31,847 Hz at 37 °C. Besides, the viscosity and echo spacing showed no apparent effect on the transverse relaxation rate. This unique feature enables visualization of glycogen signaling in vivo through T 2-weighted MRI. Two hours-post intraperitoneal injection of glucagon, a clinical drug to promote glycogenolysis and gluconeogenesis, the signal intensity of the mice\'s liver increased by 1.8 times from the T 2-weighted imaging experiment due to the decomposition of glycogen. This study provides a convenient imaging strategy to non-invasively investigate glycogen metabolism in the liver, which may find clinical applications in metabolic diseases.
摘要：
糖原在葡萄糖代谢中起重要作用。肝脏糖原成像，体内主要的糖原储库，可能为许多代谢紊乱提供新的线索。13C磁共振波谱(MRS)已成为监测体内糖原的主流办法。然而,标准临床磁共振成像（MRI）扫描仪的特殊硬件设备限制了其临床应用。在这里，我们利用内源性糖原作为基于T2的松弛造影剂,对体内肝脏糖原代谢进行成像.体外实验结果表明，糖原的横向松弛率与浓度密切相关，pH值,和场强。基于Swift-Connick理论,我们表征了糖原的交换特性，并在37°C下测量了糖原的交换速率为31,847Hz。此外,粘度和回波间距对横向弛豫率无明显影响。这种独特的特征使得能够通过T2加权MRI在体内观察糖原信号传导。腹膜内注射胰高血糖素后两小时，一种促进糖原分解和糖异生的临床药物，由于糖原的分解，小鼠肝脏的信号强度从T2加权成像实验中增加了1.8倍。这项研究提供了一种方便的成像策略，用于非侵入性地研究肝脏中的糖原代谢，这可能在代谢性疾病中找到临床应用。
