D-Glucose and 3-O-Methyl-D-glucose (3OMG) have been shown to provide contrast in magnetic resonance imaging-chemical exchange saturation transfer (MRI-CEST) images. However, a systematic comparison between these two molecules has yet to be performed. The current study deals with the assessment of the effect of pH, saturation power level (B₁) and magnetic field strength (B₀) on the MRI-CEST contrast with the aim of comparing the in vivo CEST contrast detectability of these two agents in the glucoCEST procedure. Phosphate-buffered solutions of D-Glucose or 3OMG (20 mM) were prepared at different pH values and Z-spectra were acquired at several B₁ levels at 37°C. In vivo glucoCEST images were obtained at 3 and 7 T over a period of 30 min after injection of D-Glucose or 3OMG (at doses of 1.5 or 3 g/kg) in a murine melanoma tumor model (n = 3–5 mice for each molecule, dose and B₀ field). A markedly different pH dependence of CEST response was observed in vitro for D-Glucose and 3OMG. The glucoCEST contrast enhancement in the tumor region following intravenous administration (at the 3 g/kg dose) was comparable for both molecules: 1%–2% at 3 T and 2%–3% at 7 T. The percentage change in saturation transfer that resulted was almost constant for 3OMG over the 30-min period, whereas a significant increase was detected for D-Glucose. Our results show similar CEST contrast efficiency but different temporal kinetics for the metabolizable and the nonmetabolizable glucose derivatives in a tumor murine model when administered at the same doses.

中文翻译：

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小鼠肿瘤模型中天然葡萄糖和 3-O-甲基-D-葡萄糖之间 MRI 化学交换饱和转移 (CEST) 特性的体外和体内比较

D-葡萄糖和 3-O-甲基-D-葡萄糖 (3OMG) 已显示在磁共振成像-化学交换饱和转移 (MRI-CEST) 图像中提供对比度。然而，尚未对这两种分子进行系统比较。目前的研究涉及评估 pH 值、饱和功率水平 (B ₁ ) 和磁场强度 (B ₀ ) 对 MRI-CEST 对比的影响，目的是比较这两种药物在体内的 CEST 对比可检测性。葡萄糖CEST 程序。在不同的 pH 值下制备 D-葡萄糖或 3OMG (20 mM) 的磷酸盐缓冲溶液，并在几个 B _{1下获得 Z 光谱}水平在 37°C。在小鼠黑色素瘤模型（n = 3-5 只小鼠每个分子、剂量和 B ₀场地）。对于 D-葡萄糖和 3OMG，在体外观察到 CEST 反应的明显不同的 pH 依赖性。两种分子在静脉内给药（3 g/kg 剂量）后肿瘤区域的 glucoCEST 对比增强效果相当：3 T 时为 1%–2%，7 T 时为 2%–3%。饱和转移的百分比变化3OMG 的结果在 30 分钟内几乎保持不变，而 D-葡萄糖则显着增加。我们的研究结果显示，当以相同剂量给药时，肿瘤鼠模型中可代谢和不可代谢葡萄糖衍生物的 CEST 对比效率相似，但时间动力学不同。