As I get older, I often hear from colleagues and friends about the medical problems they are facing. Sound familiar? And have you noticed how many times the term “MRI” has come up when someone is talking about a medical problem? MRI, or magnetic resonance imaging, has become the “Cadillac” of medical imaging. MRI provides for the non-invasive imaging of the human body for diagnostic purposes.
You might think of MRI as an evolution of the x-ray, but MRI is more sensitive and it can see our tissues and organs more clearly. MRI can be used to identify cancerous growths, blood vessel abnormalities, identify internal bleeding sites or other medical situations where abnormal tissue needs to be visualized. In a word, MRI has revolutionized medicine. This technique is more sensitive than other procedures and in many cases, it represents the ultimate imaging diagnostic tool.
MRI machines create a strong magnetic field that causes all the atoms in your cells to spin in the same direction. While in the magnetic field, these atoms are exposed to radio waves that energize the nucleus of each atom. When the nucleus slows down, these waves are re-emitted. Special films use these waves to make a detailed image of your internal organs and tissues, just like photographic films use light to make pictures.
The same technology can be scaled down to study how biochemical molecules interact in cells. One technique that has been developed is magnetic resonance spectroscopy. It can detect cellular structures down to 1/100th of a millimeter. This is about the size of one of our red blood cells. Using this type of MRI, scientists have been able to take detailed photos of small structures in tissues and cells.
The magnetic resonance microscope allows scientists to see even further down into molecular levels. The microscope can peer down to 300 nanometers, which is about 1/600th of the thickness of a credit card. The key feature that allows this level of resolution is a new sensor made of nitrogen atoms in a diamond film. The nitrogen atoms are spaced out at a specific depth in the film, and they give off a fluorescent color in a strong magnetic field. The exact color they produce depends on their spin in the magnetic field. The difference in the color of the emitted light depends on the specific atoms that are nearby and produces a distinct signature. That means you can use the emitted fluorescence color to identify the precise biochemical molecules that are interacting.
With this technology, scientists can determine what biomolecules are binding to each other, how they might be changing as the result of their interaction and other aspects of the chemistry occurring inside living cells. This is a powerful way to know what molecules are interacting with each other. Now that we can watch biochemical reactions inside a living cell, we can understand the intimate workings of cells and invent new ways to diagnose and manage diseases.