Mapping Extracellular pH of Gliomas in Presence of Superparamagnetic Nanoparticles: Towards Imaging the Distribution of Drug-Containing Nanoparticles and Their Curative Effect on the Tumor Microenvironment

Figure 3

Region of interest (ROI) analysis for the average relaxation rate () and extracellular pH () before and after infusion of SPIO-NPs for all RG2 tumor-bearing rats that underwent coinfusion of TmDOTP⁵⁻ and probenecid (). The ROI analysis is based on concentric 1 mm circular rings drawn from the center of mass of the tumor. (a) Average values in different ROIs for intrinsic contrast, after infusion of TmDOTP⁵⁻, and after infusion of TmDOTP⁵⁻ with SPIO-NPs. The average enhancement was highest inside the tumor (ROIs 1–3) compared to tumor edge (ROI 4) and nontumor regions (ROIs 5–9). The dashed line represents the tumor edge. Small enhancement was observed after infusion of TmDOTP⁵⁻. However, much higher enhancement was observed upon infusion of SPIO-NPs. See Table 1 for details. (b) The average values in different ROIs before and after infusion of SPIO-NPs. The values measured before and after infusion of SPIO-NPs were similar, both inside and outside the tumor. The was lowest in the tumor and highest in the healthy/nontumor tissue farthest from the tumor. Low was also measured on the tumor margin. See Table 2 for details.

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