Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Italy.
Magn Reson Med. 2014 Jan;71(1):326-32. doi: 10.1002/mrm.24664. Epub 2013 Mar 25.
A novel method based on the use of Yb-HPDO3A as MRI Para-CEST agent for in vivo pH mapping of the tumor region in a melanoma murine model is reported. This method does not require the knowledge of the concentration of the imaging agent.
C57BL/6-mice were inoculated with B16-F10 cells. CEST-MR images of tumor and bladder were acquired upon the i.v. administration of Yb-HPDO3A (1.2 mmol/Kg). pH was assessed by the use of a ratiometric method.
Yb-HPDO3A distributes well in the extracellular space of the tumor allowing the detection of good levels of saturation transfer (ST). It is excreted throughout kidneys and accumulated in the bladder thus yielding a strong CEST signal from urine. By comparing the ST% obtained upon selective irradiation of the two OH resonances belonging to the two isomeric forms of Yb-HPDO3A, it has been possible to measure the extracellular pH for each voxel (0.22 mm(3) ). The obtained pH-maps of tumors show a great heterogeneity. Marked differences are associated to tumor staging.
The application of Yb-HPDO3A to measure extracellular tumor pH provides a good spatio-temporal resolution and it does not require the prior knowledge of the contrast agent concentration. The herein reported data support the potential clinical translation of Yb-HPDO3A.
报道一种新型方法，该方法基于使用 Yb-HPDO3A 作为 MRI Para-CEST 造影剂，用于黑色素瘤小鼠模型的肿瘤区域的体内 pH 图谱绘制。该方法不需要造影剂浓度的知识。
C57BL/6 小鼠接种 B16-F10 细胞。在静脉注射 Yb-HPDO3A（1.2mmol/Kg）后，获取肿瘤和膀胱的 CEST-MR 图像。使用比率法评估 pH 值。
Yb-HPDO3A 在肿瘤的细胞外空间分布良好，允许检测到良好的饱和转移（ST）水平。它通过肾脏排泄，并在膀胱中积累，从而从尿液中产生强烈的 CEST 信号。通过比较选择性辐照 Yb-HPDO3A 的两种 OH 共振所获得的 ST%，可以测量每个体素（0.22mm(3)）的细胞外 pH 值。获得的肿瘤 pH 图谱显示出很大的异质性。与肿瘤分期相关的显著差异。
应用 Yb-HPDO3A 测量细胞外肿瘤 pH 值提供了良好的时空分辨率，并且不需要造影剂浓度的先验知识。本文报道的数据支持 Yb-HPDO3A 的潜在临床转化。
