My Spine - Lumbar
What is an MRI (magnetic resonance imaging) scan?
This scan is performed with magnetism. A very large magnet aligns and
realigns the molecules of the body and a computer then interprets the signals
that are received and turns them into images. These images are really very
clear and all the tissues in the body can be seen in great detail. As with CT
scans, contrast can be used to give greater detail to blood vessels and also to
indicate inflammation and cancer.
Since this technology works with a large magnet, patients who have certain
metal implants cannot undergo this test.
When you undergo this test you will be placed in a machine that has a narrow
tunnel and claustrophobic patients frequently need some form of sedation for
this procedure. The machine makes quite a lot of metallic banging and clat-
tering noises and you will usually be offered earphones to block out the noise
and in some institutions soft music is piped through these.
Several types of pictures are taken. The most frequently used images are T1-
weighted and T2-weighted scans. This is a description of the different ways
that the scan manipulates the magnetic field of the tissue that is being exam-
ined. It is not important to know anything about the difference between these
different types of MRI pictures that are taken.
It is, however, useful to know that there are several cuts (planes in which the
body is examined) that are done. The most frequently used cuts are the sagit-
tal images. These are images that are taken of your body from a side-on view.
They are very useful in giving an overview of the spine in its entirety.
The images that are more important for depicting the finer detail of the
pathology are the axial cuts or planes that are taken straight through the spine
and are like slices taken of a sausage. The nerves that are leaving through the
foramina are seen side-on and look like little worms as they leave the spinal
canal. This way your specialist can see a lot of detail about the nerves and any
compression of the nerves.
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