Evaluating pH in the Extracellular Tumor Microenvironment Using CEST MRI and Other Imaging Methods

Figure 18

CEST MRI of tumor pHe with iopamidol. (a) A CEST spectrum the agent shows two CEST effects at 4.2 and 5.5 ppm. Both CEST effects are dependent on saturation conditions, which indicates that CEST MRI measurements of pH should be performed with optimized saturation conditions for best results. (b) The calculated pH based on a ratio of the CEST effects is correlated with experimental pH measured with an electrode. (c) An anatomical image shows the locations of the kidneys. (d) The pixelwise pHe map of the kidneys shows a homogenous distribution of pHe values with an average pHe of 5.8. Reproduced with permission from [66, 98].

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