The Advent of NMR and its Impact on Chemistry and Medicine

Back in 1946, a pair of articles penned by Felix Bloch from Stanford and Edward Purcell from Harvard appeared in the Physical Review, a scientific journal. While seemingly only captivating to theoretical physicists at first glance, these articles would pave the way for a technique that would revolutionize both chemistry and medicine.

The Pivotal Role of Hydrogen Atoms in NMR

Bloch and Purcell aimed to gauge the strength of minuscule magnetic fields generated by hydrogen atoms. Their method involved positioning a hydrogen-laced compound between the poles of a large magnet. They discovered that the poles of the tiny hydrogen atom "magnets" were drawn to the opposing poles of the larger magnet. Intriguingly, they found that they could compel these hydrogen magnets to adopt a less preferred orientation by applying radio wave energy.

Other scientists quickly built upon Bloch and Purcell's discoveries, observing that not all hydrogen atoms in a sample absorbed the same energy amount. As the energy absorption was reliant on the hydrogen atoms' unique chemical environment, scientists could determine many unknown compounds' molecular structures.

The Groundbreaking Technique and its Inventors

In a few years, the novel technique dubbed nuclear magnetic resonance (NMR) was adopted globally. Bloch and Purcell were awarded the Nobel Prize in Chemistry in 1952 for this revolutionary research. In the early 1970s, a group of scientists decided to experiment with living tissue. They placed a living mouse in a large magnet, a procedure that proved to be a significant breakthrough.

The mouse's body's hydrogen atom nuclei aligned with the external field and could be disrupted using low-energy radio waves. Remarkably, the 'relaxation' time of the various nuclei was linked to the health of the tissue they were in. Before long, scientists had developed an instrument that could produce images of body sections. By the late 1970s, they had created an instrument capable of generating images of the entire human body.

How MRI works

Nuclear magnetic resonance imaging had been born, an extraordinary medical investigation technique that was noninvasive, used no dangerous radiation, and held so much promise as a tool for diagnosing conditions ranging from cancer and joint problems to spinal injuries and strokes. MRI uses electromagnetic waves of a certain frequency range (in the radio wave spectrum) that penetrate the body and act on the protons of atomic nuclei. The protons in question are first made to align by a strong magnetic field (technically referred to as spin), then are perturbed (spin reversal) by the waves, and finally are allowed to realign.

The entire process is recorded with special instruments, then sophisticated software transforms the data into images. The procedure is completely harmless, because the magnetic field and radio waves have no effect on our bodies.MRI has shown that most of us use more than 90 percent of our brains, although not necessarily all parts at the same time; thus disproving the claim that we use only 10 percent of our brains. But it is not excluded that there are indeed people who use only 10% of their brains: those who believe in this myth.