ESR imaging on a solid-tumor-bearing mouse using spin-labeled dextran

Area of Science:

• Biomedical Imaging
• Medical Physics
• Chemistry

Background:

• Electron Spin Resonance (ESR) imaging is a developing technique for visualizing biological tissues.
• Developing effective contrast agents is crucial for enhancing the sensitivity and specificity of ESR imaging.

Purpose of the Study:

• To evaluate the efficacy of two spin probes, CPROXYL (low molecular weight) and TEMPO-DX (polymer), for tumor imaging using ESR.
• To compare the in vivo behavior and tumor accumulation of CPROXYL and TEMPO-DX.

Main Methods:

• Administered CPROXYL and TEMPO-DX to mice with transplanted tumors via intraperitoneal and intravenous injections.
• Analyzed probe accumulation and distribution using X-band ESR and ESR imaging.

Main Results:

• CPROXYL was rapidly excreted in urine regardless of administration method.
• TEMPO-DX showed poor absorption via intraperitoneal injection but concentrated in tumor tissue with intravenous injection.
• ESR imaging confirmed TEMPO-DX accumulation in the tumor, while CPROXYL accumulated in the bladder.

Conclusions:

• TEMPO-DX exhibits a longer in vivo half-life and superior tumor-targeting capability compared to low molecular weight spin probes.
• TEMPO-DX holds potential as a specific ESR imaging agent for tumor detection and characterization.