Introductory Chemistry: A Molar Relaxivity Experiment in the High School Classroom

Abstract

Dotarem and Magnevist, two clinically available magnetic resonance imaging (MRI) contrast agents, were assessed in a high school science classroom with respect to which is the better contrast agent. Magnevist, the more efficacious contrast agent, has negative side effects because its gadolinium center can escape from its ligand. However, Dotarem, though a less efficacious contrast agent, is a safer drug choice. After the experiment, students are confronted with the FDA warning on Magnevist, which enabled a discussion of drug efficacy versus safety. We describe a laboratory experiment in which NMR spin lattice relaxation rate measurements are used to quantify the relaxivities of the active ingredients of Dotarem and Magnevist. The spin lattice relaxation rate gives the average amount of time it takes the excited nucleus to relax back to the original state. Students learn by constructing molar relaxivity curves based on inversion recovery data sets that Magnevist is more relaxive than Dotarem. This experiment is suitable for any analytical chemistry laboratory with access to NMR.

Preparation of a Cobalt(II) Cage: An Undergraduate Laboratory Experiment That Produces a ParaSHIFT Agent for Magnetic Resonance Spectroscopy

“…After isolating the complex as a solid, the material is confirmed by electrospray ionization mass spectrometry (ESI MS, Figure S1) prior to preparing NMR samples (Figure S2). Students further analyze their product by 1 H NMR spectroscopy and are typically given the 13 C NMR spectrum (Figure S3). This two-step procedure is fairly straightforward and students are generally successful in obtaining product in two afternoons.…”

“…A search of this Journal for examples of MRI contrast agents yields a single article on Gd(III) complexes and measurements of T 1 relaxivity. 1 The lack of examples is surprising given the emphasis on paramagnetic states of metal ions in undergraduate inorganic chemistry courses. Notably, there are several articles in this Journal on magnetic susceptibility measurements 2−5 and EPR spectroscopy 6 that lay the foundation for paramagnetic metal ion interactions with ligands.…”

“…7 Paramagnetic shifts are reported, as part of the characterization of a complex or a metalloenzyme, but not with an emphasis on imaging. 6,7 The undergraduate laboratory experiment described here is designed to give students an appreciation for paramagnetic metal ions and their effect on 1 H NMR resonances including changes in shift and relaxation time constants. The experiment focuses on the synthesis of a paramagnetic metal ion complex that produces highly shifted proton resonances.…”

Targeted Gold Nanoparticle–Oligonucleotide Contrast Agents in Combination with a New Local Voxel-Wise MRI Analysis Algorithm for In Vitro Imaging of Triple-Negative Breast Cancer

“…Additionally, the GBCA’s longitudinal T1 mapping is also maximized using algorithms with global analysis [39,40,41] and local voxel value analysis [37,38] followed by voxel-wise normalization [42] employing control anatomical structures. The above methods can greatly augment conventional methods for obtaining superior contrast in the longitudinal T1-Weighted (T1-W) MRI images, such as variations in slice thickness, field of view (FOV), image acquisition (repetition TR/ echo TE) time and acquisition matrix [43,44,45].…”

The Heteronuclear Multiple-Quantum Correlation Experiment: Perspective from Classical Vectors, Nonclassical Vectors, and Product Operators

“…Concerning the educational literature, NMR is a recurrent topic. Many didactic papers are devoted to structure elucidation [19][20][21][22], to review media [23,24], and other applications [7,8,25,26]. However, the knowledge behind spin evolution in modern 2D-NMR is beyond the grasp of many users since it is not mandatory to interpret NMR spectra.…”