Rules of the Day 2-4-091. The popular medical diagnostic technique of magnetic resonance imaging (MRI)is based on the same principles as NMR, namely theflipping (i.e. resonance) of nuclear spins of protons byradio frequency irradiationwhen a patient is placed in a strong magnetic field. Magnetic field gradientsare used to gain imaging information, and rotation of the gradient around the center of the object gives imaging in an entire plane (i.e. slice inside patient). In an MRI image, you are looking at individual slices that when stacked make up the three-dimensional imageofrelative amounts of protons, especially the protons from water and fat, in the different tissues. [Memorize the preceding passage, as it will be worth 12 points on each exam this semester. I am not kidding] Click here for a handout on MRI.2. Organometallic reagents such as organolithium reagents, Grignard reagents, and Gilman reagentsare important because the are easy to prepare and they place a partial negative charge on a carbon atom.
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Magnetic resonance imaging, Grignard Reagents, partial negative charge