Even if you’ve never had one, you’re probably familiar with the term “magnetic resonance imaging,” or MRI. Although this medical diagnostic technique did not become widely used until the latter part of the 20th century, it quickly rose to become a mainstay of the medical profession, offering an unparalleled view of the body’s internal structure and mechanisms, that has allowed diagnostic imaging to evolve by leaps and bounds. The MRI technique has also helped physicians more thoroughly identify health problems in their nascent stages, when treatment is generally most effective.
The magnetic resonance imaging technique is based on – well, magnets. Remember how a compass always points in a N-S direction? That’s based on the charge – a very small charge – that causes the needle to align with the magnetic pole of the earth. Similarly, if you place a magnet near a compass, the compass needle will realign itself with that magnetic field.
The human body is composed largely of water and fat, both of which contain large amounts of hydrogen atoms. Like the compass needle, these hydrogen atoms have a slight magnetic charge. When a large and very powerful magnet, like that found in the magnetic resonance imaging machine, is placed near those atoms, it causes them to align in a specific way. By measuring that alignment, the scanner can make images of your organs and other internal features.
Okay, so it sounds complicated. But fortunately for you, or anyone who is preparing to undergo an MRI scan, the procedure itself is pretty straightforward. You’ll need to change into a hospital dressing gown and remove any metal from your body (remember, the MRI is based on magnetism, and any metal you’re wearing can cause a disturbance). In some cases, you may be injected with a special dye to aid in visualizing your organs.
Depending upon the scan your physician wants to have performed and the imaging center you’re visiting, you’ll either lie down or sit up during the scan itself. In the first option, you’ll lie on a flat table which is attached to the scanner. The scanning machine is like a large tube. When the scan begins, the table you’re lying on will move slowly into the scanner until you are completely inside the machine. Because the sound of the scanner can be loud, you’ll usually be offered a set of headphones to block the noise. You’ll also hear the technician speaking to you through the headphones when there are special instructions – for instance, if the technician wants you to inhale while an image is being produced.
In the sitting-up MRI scan, you will sit in a special chair attached to the scanner, and the scanner will orbit around you.
Most MRI scans take less than 30 minutes – but when used to diagnose potential health problems, they can offer years of better health.
