Within the framework of the INVENNTA project, at INL, we have been working on different strategies in order to obtain safer and more efficient contrast agents as an alternative to the traditional gadolinium (Gd) compounds currently used in clinics.

Contrast agents are chemical compounds used in magnetic resonance to obtain clinical imaging of organs and internal tissues with higher resolution. The mechanism of action of contrast agents is based on their interaction with hydrogen atoms of water molecules present in the organism. As a result of this interaction, and because the adult human body is formed of more than 60% water, it is possible to obtain internal anatomical images in grayscale, which are subsequently analyzed by medical specialists to make a patient diagnosis.

“Depending on how much more efficient these contrast agents are, we will get more resolution in the clinical images and we can better differentiate the healthy tissues from the harmful tissues of patients, therefore enabling an earlier and more effective diagnosis”, says Manuel Bañobre, INL researcher.

“Contrast agents are divided into two types: T1 (white contrast) and T2 (dark contrast). So far, T1 agents are conventionally used in clinics, mainly formed by gadolinium salts. However, these have major disadvantages related to their potential toxicity and short retention time in the body before being excreted”, added the chemist.

A strategy for safer and more efficient contrast agents is the use of nanoparticles of magnetic iron oxides, which present higher biocompatibility and manage to increase dark contrast, acting as a T2 contrast agent.

Another strategy that is being developed at INL is to combine into one single platform materials that have the ability to offer an active contrast in both T1 and T2 modalities. “In this way, using the same contrast agent, we will be able to separately acquire images in both modes and thus filter those interferences that each of them present separately, i. e. adipose tissue for images acquired in mode T1 (using T1 contrast agents) and bleeding or internal blood clots in the case of images acquired in T2 mode (using T2 contrast agents), which can lead specialists to a wrong analysis of the images and diagnosis”, explains Manuel Bañobre.

The activities carried out in this project are oriented to cover the entire process from the synthesis and physical-chemical characterization of materials to its application in vivo, in collaboration with our colleagues from the Neurosciences group, at the University Hospital of Santiago de Compostela.

“At INL, we mainly focus on the synthesis and physical characterization of nanoparticles: The magnetic nanoparticles are obtained from the corresponding iron salts by hydrothermal reaction at moderate temperatures of 180 ºC, while gadolinium compounds require a more complex organic synthesis”, explains Noelia Guldris, PhD student involved in this research area.

“The efficiency of these contrast agents will be determined by their chemical-physical properties: composition, particle size and distribution, magnetic and relaxometric properties, etc., which are characterized by different techniques and equipment available at INL”, concludes the PhD student.