Targeted Dual-Modality Imaging of Inflammation Using ¹⁸F-Radiolabeled Iron Oxide Microparticles.

Area of Science:

• Biomedical Imaging
• Molecular Imaging
• Nanotechnology

Background:

• Noninvasive mapping of vascular inflammation with high resolution is a significant challenge.
• Dual-modality imaging probes integrating PET and MRI offer a promising solution.

Purpose of the Study:

• To develop and evaluate a novel ¹⁸F-labeled hydrophilic sulfotetrazine for bioorthogonal conjugation.
• To create dual-modality PET/MR imaging probes targeting vascular cell adhesion molecule-1 (VCAM-1) for inflammation detection.

Main Methods:

• Engineered an ¹⁸F-labeled sulfotetrazine for inverse electron demand Diels-Alder (IEDDA) click chemistry with BCN-functionalized MPIOs.
• Generated dual-modality PET/MR probes (¹⁸F-MPIOs@αVCAM-1) by conjugating the tracer to anti-VCAM-1 antibody-coated MPIOs.
• Utilized dynamic immuno-PET/MR imaging in a murine sepsis model.

Main Results:

• The ¹⁸F-reagent demonstrated high aqueous solubility, stability, and fast reaction kinetics with BCN.
• Specific tracer accumulation was observed in lungs and kidneys, correlating with VCAM-1 overexpression in the sepsis model.
• High-resolution T2*-MRI confirmed precise retention of the probe in the renal cortex.

Conclusions:

• The developed ¹⁸F-sulfotetrazine is a versatile tool for late-stage functionalization of nanocarriers.
• This strategy enables the creation of next-generation multimodal probes for real-time tracking of inflammatory pathologies.
• The dual-modality PET/MR approach provides enhanced spatial and molecular resolution for inflammation imaging.