Gadolinium Complexes as MRI Contrast Agents for Diagnosis

Magnetic resonance imaging (MRI) has a pivotal role in disease diagnosis, especially with the use of contrast agents which are paramagnetic compounds. Gadolinium complexes attract scientists' attention because of their positive contrast enhancement. These complexes have been applied clinically to increase contrast and result in better anatomical images. This includes the imaging of vasculature, and organs, such as the liver and the brain. We highlight the features of the structure of chelates and the mechanism of contrast enhancement via the bench-to-bedside development of Gd complexes. New complexes were prepared to generate high contrast enhancement, in addition, to have an affinity towards targeted biomolecules and stay at the site of interests for a reasonably long period of time. These examples demonstrate the importance of precise chelate designs to optimize targeting, and at the same time minimize the toxicity. By understanding the chemistry, molecular interactions and contrast enhancement patterns in disease models, new complexes could be designed as potential contrast agents for better imaging. In an era of diagnosis and therapy at molecular level, contrast agent development focuses on the targeting of specific site of interests, which allows contrast-enhanced MRI providing functional or physiological information for advanced diagnosis.