20 Thus, the development of next-generation high-relaxivity GBCAs meets a real medical need. Given the history of NSF and Gd retention in the brain and other organs, the lowest GBCA dose should be used that provides enough enhancement for diagnosis in routine practice. 18 MRI sequences and post-processing techniques may be developed to replace or decrease the use of contrast agents (for example 4D MRI instead of MRA and CEST imaging) or hybrid technologies such as PET/MR may rely on radiotracers in lieu of MR contrast agents. 16 Alternatively, the development of sequences, arrays of coils, k-space strategies, stochastic imaging, and machine learning-based image analysis procedures 17 have provided numerous opportunities to improve image contrast in MRI. Recent work has also been done to improve the relaxivity and in vivo lifetime of metal-free, nitroxide-based contrast agents. A promising example is chemical exchange dependent saturation transfer (CEST) MRI, which can generate clinically useful contrasts using diamagnetic molecules with exchangeable protons in amine, amide and hydroxyl groups. 8 This has led researchers to pursue contrast mechanisms that do not require metals. Metal-based paramagnetic contrast agents are limited by the intrinsic toxicity of many metal ions, their persistence in tissue, and their ability to provide only one type of contrast. The future of MR contrast may see a replacement of Gd with alternative metals, such as manganese (Mn) or iron-based agents.

3 Recently, however, there has been concern about Gd de-chelation from GBCAs and possible effects of bioaccumulation in the central nervous system. 1 Adverse side effects of GBCAs are uncommon, 2 and the reported GBCA-associated incidence of nephrogenic systemic fibrosis (NSF) has declined due to pre-MR patient screening and replacement of linear GBCAs with macrocyclic compounds. Gadolinium (Gd)-based contrast agents (GBCAs) dominate the current contrast-enhanced magnetic resonance imaging (CE-MRI) market and are proven to increase the efficacy of diagnostic magnetic resonance (MR) scans. This article is accredited for one SA-CME credit and is available at /SAM2.

Tea mr contrast agent