MRI Introduction For Middle
For middle school students, MRI could be introduced
through basic science concepts, such as atoms and
molecules. This introduction is by B. M. Damon.
What is MRI?
MRI stands for Magnetic Resonance Imaging. It is a
way of using a big magnet (called a magnetic resonance
imager) to make pictures of the insides of things -
people, chicken eggs, fruit - just about anything you
can think of.
Doctors use MRI every day to make pictures of people
who have been injured or are sick. Scientists at the
U of I also use MRI to study biology. In this
project, you will join them in being the first people
ever to use MRI to look at a chicken as it grows and
develops inside of its egg.
Figure 7. Side view of human head (Image courtesy of
Dr. Andrew Webb.)
Everything that you see is made of things called
atoms. An atom is like a very, very small solar
system. As you know, the sun is at the center of the
solar system. Just like the solar system, there is
something at the center of an atom. It is called the
nucleus. So the nucleus of an atom is like the sun in
our solar system. Around the sun there are planets.
They orbit the sun. In an atom, there are things
called electrons that orbit the nucleus.
There are many different types of atoms. All of them
are electric. The nucleus of an atom has a positive
charge, while the electrons have a negative charge.
Some atoms are also magnets. For example, a hydrogen
atom is a magnet.
Two or more atoms joined together are called a
molecule. For example, when two hydrogen atoms and an
oxygen atom join together, they make a water molecule.
Because the water molecule includes two magnetic
hydrogen atoms, the water molecule is a kind of
This is very convenient for us, because things like
chicken eggs have a lot of water molecules in them.
There are water molecules in the yolk and there are
water molecules in the egg white. So there are
millions and millions of little water magnets swimming
all around the inside of a chicken egg! When you make
your MRI pictures, you are actually making a picture
of those water molecules.
In your egg project, someone will take the egg and
put it inside of the MRI magnet. You will then use
your computer to make an image. In order to do that,
the MRI magnet has to zap the little water magnets
with some energy. It will do this over and over
again. It may take as little as 10 or 12 seconds or
as much as a couple of minutes to do this.
Eventually, the MRI magnet will be done zapping and a
computer will make an picture of the inside of the
What will the picture look like?
The picture will be of a slice of the egg - sort of
like if you slice through a hard-boiled egg with a
knife. This picture will be a square, 60 mm by 60 mm
(about 2 1/2 inches by 2 1/2 inches). We call these
dimensions the field of view.
The water magnets in the yolk behave differently from
the water magnets in the white. And so you might
notice that the yolk is dark gray and the white is
light gray. This really doesn't have anything to do
with the color of the yolk and the white, though. You
can change the contrast in the image to make the yolk
lighter and the white darker. It is sort of like
looking through red cellophane at an object, and then
looking at the same object through blue cellophane.
It looks different, but you are really just looking at
two different aspects of the same thing. Of course,
you will eventually be able to see a chicken
developing - a pretty amazing thing.
So what else can you do?
Well, one thing that you can do is view the egg from
different angles - like cutting through a hard-boiled
egg sideways vs. crossways vs. lengthwise.
Another thing you can do is move the position of the
slice forward or backward - like cutting through the
egg in a different spot.
You can make the field of view smaller. This is like
zooming in: it will make the egg bigger (but if you
zoom in too much, it will make the images look weird -
try it!). You can also make the field of view larger.
This is like zooming out: it will make the egg
You can cut very, very thin slices - as thin as a
millimeter - or very thick slices - as thick as a
You can make the same image over and over and average
them all. This will make a nice-looking image, but
will take a while.
What should I do during the experiments?
You should explore the inside of the egg as much as
possible. View the egg from different angles. Move
the slice all around so that you can find different
things. Zoom in. Zoom out. Try to make your images
look as good as possible.
Don't be worried if the image turns out funny. Even
the scientists at the U of I have to experiment with
things a little (a lot, sometimes!) to get things to
turn out right.
Most of all, you should have fun doing this science
project. You will be doing something that no one has
ever done before - making MRI pictures of a developing
chicken egg. Seeing something for the very first time
is the fun of science. Have fun in your experiments
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