Spotlight – Cyclodextrin-Based Organic Radical Contrast Agents for in vivo Magnetic Resonance Imaging


Published September 8, 2025

Contrast agents (CA) for magnetic resonance imaging (MRI) are widely used in clinical practice to improve diagnostic accuracy. Despite the success of gadolinium (III)-chelate-based CAs due to their excellent relaxation properties, some safety concerns have been raised.

Dr. Lucio Melone (Politecnico di Milano, Italy) developed a set of cyclodextrins water soluble contrast agents functionalized with different kinds of nitroxide radicals to be tested both in vitro and in vivo at the Finnish Biomedical Imaging Node.

In vivo MRI experiments at 9.4 T in a glioma rat model showed a good relaxivity and an improved retention of the contrast for at least 60 minutes, confirming an improved stability of cyclodextrins nitroxide radicals also in vivo.

Read more here:

T1 maps measured in rats bearing C6 brain tumor
T1 maps measured in rats bearing C6 brain tumor (tumor indicated with yellow arrow in pre-contrast images) before and after injection of cyclodextrins and Gd-DTPA contrast agents. Figure have been adapted from Franco et al, 2023: https://doi.org/10.1002/cphc.202300100. Used under a Creative Commons CC-BY 4.0 license.

About the Finnish Biomedical Imaging (FiBI) Node

The Finnish Biomedical Imaging Node (FiBI) is a multi-sited, multimodal Node covering biomedical imaging from mouse to man. The spearhead imaging technologies of the FiBI Node include 1) preclinical and human PET imaging and PET tracer development, 2) preclinical high-field MRI, 3) magnetoencephalography (MEG), and 4) optical intravital imaging, coupled with a broad repository of imaging tracers and probes, numerous animal models from mice to pigs, and diverse stimulation systems for both animals and humans. The key expertise and main research applications focus on major challenges especially in cardiovascular and metabolic diseases, neuroscience, and cancer. With wide coverage of imaging modalities and expertise, the FiBI Node provides exceptional opportunities not only for basic research but also for translational research from small animals to larger animals to humans and to the clinic within a single Node.


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