What Is An Mri?

If you have been injured in an accident the most important task you have is to seek medical attention immediately. After your injuries have been treated and your condition has been diagnosed you may be ordered by your physician to get more tests. One of the test they may order is called Magnetic Resonance Imaging (MRI). This is a non-invasive way to take internal pictures of the body. Unlike X-Rays and Computed Tomographic (CT) scans, which use radiation, the MRI uses powerful magnets and radio waves. The MRI scanner contains a magnet. The magnetic field produced by an MRI is about 10 thousand times greater than the earth's.

This is done by the magnetic field forcing hydrogen atoms in the body to line up in a certain way, much the same way a needle on a compass moves when you hold it near a magnet. When radio waves are sent toward the lined-up hydrogen atoms, they will bounce back. A computer will then record the signal. Different signals are sent by different tissues. The signal sent back by healthy tissue is slightly different than the signal sent by cancerous tissue.

Single MRI images are called slices and these slices can be stored on a computer or printed on film. The width of the slice can affect the quality of the image produced. You can have an MRI performed through clothing. However, because the magnet is very, very strong, certain types of metal can cause significant errors, called artifacts, in the images.

The accuracy of the MRI may not be as fool proof as we have been lead to believe. An MRI reading may indicate that there is not a problem, a negative MRI, but in actuality there is a problem that is not detected. MRI's have been regarded as a highly effective way to get information on internal issues in the body. They have been used for years as evidence of injuries caused by an auto accident. The most common injury from a car accident found would be a bulging or herniated disc.

One man reported that he had an MRI after a fall and the scan showed nothing except bulging disks. He was told that bulging disks were normal. He was instructed to do neck exercises. He followed the exercise regime and eventually felt better. A year later he fell again and suffered the same symptoms but they were more painful and debilitating. The symptoms didn't lessen so he had another MRI which showed a nerve impingement that was diagnosed as serious enough to cause paralysis if he did not have surgery to widen four to five vertebrae and free the trapped nerves.

There are many explanations as to why scans can render such diverse results. MRI's are performed by Radiology centers which then send the reports to the doctors. Doctors can never be sure if the MRI was done well, interpreted well or if the machine is used is the most current available. Also, the manner that the scan was performed can affect the results. If the width of the picture slice is too wide it might be hard to read. Some companies don't even take an MRI of the entire spine if a cervical, lumbar or thoracic MRI is ordered. They set gaps between the slices. This cuts down on the time required completing the MRI, but it also creates inaccuracies since there are no images of the gaps. If the disc herniation falls within the gap there would be no image of it. The thought is that more MRI's can be scheduled by reducing the time required for each MRI. This will result in inaccurate reselts as well as more profits for the testing facility.