Shows like
”
ER
”
and
”
Medical Investigation
”
have their own terminology. What does it really mean when a
character yells,
”
Get me a CBC and Chem seven, STAT
”
? And what the heck is an EEG, anyway?
Shows like “ER” and “Medical Investigation” have their own terminology. What does it really mean when a character yells, “Get me a CBC and Chem seven, STAT”? And what the heck is an EEG, anyway?
As part of a new series, we will be bringing you the idiot’s guide to medical procedures, though we hope you’re smart enough to realize a “do not try this at home” warning should be assumed. First up: MRI.
A Magnetic Resonance Imaging scan, or MRI, is one of the best ways for doctors to get a good look at soft tissues in the body without having to open up a patient. They’re used to diagnose pinched nerves, multiple sclerosis and strokes, as well as to check for problems like potential aneurisms.
The average scan takes about 30 to 45 minutes, according to Rick Villegas, an MRI technologist at St. Louise Regional Hospital who has been performing scans with the technology since 1987.
“Typically it makes a lot of noise – like a jack hammer – so ear plugs are pretty standard for these scans,” said Villegas, gesturing to a large bag of orange plugs that, spilling out of the bag, resemble a big stack of Cheetos.
The system is basically a giant magnet with a tube cut into its center, known as a bore. At St. Louise, the magnet is 6 feet long, but some hospitals use 10-foot bores. A special table slides patients in and out of the tube, and their scan commences when the body part in need of study is at the isocenter, or exact center, of the magnet.
“We use the hydrogen atoms in the body to make a map of things,” said Villegas. “The human body is about 75 percent water, so there’s water in every structure. The machine is tuned to the same frequency as water; so essentially, when you enter the machine you become part of it.”
Radio imaging creates a picture of the body’s insides by measuring hydrogen levels on a point-by-point basis. To accomplish this, the radio pulse is turned off and the machine reads feedback from your body almost like sonar, assigning different variations on the gray scale for different densities of matter.
Newer versions of the MRI, called open MRI scanners are also on the market, but their use is specific.
“The bore MRI has superior imaging quality, but for patients who are extremely claustrophobic or obese – that weigh more than 350 pounds – it’s a good option.”
Since the scanner is a 1.5 Tesla magnet it does have limitations. People who have had metal implanted in their bodies during previous surgeries, who have an aneurysm clip or a pace maker are not eligible to be scanned. The MRI unit is actually outside the hospital right now in a mobile unit.
“You’ll see signs when you come in – authorized personnel only – and that’s because anything in the environment can affect the magnet. We have quite a bit of space around the trailer so that we don’t have problems.”
Proper maintenance is also a must. The magnet is cooled by liquid helium pumps, but should those fail, the system would quinch, meaning the magnetic field would be so strong it would suck all the oxygen out of the air, potentially asphyxiating any patient sitting in the tube. Not to worry, though.
“That’s never happened here and the idea is very, very rare,” said Villegas.
