Posted by: Thixia | May 1, 2008

MRI 11 of 14

MRI Disadvantages


Although MRI scans are ideal for diagnosing and evaluating a number of conditions, it does have drawbacks. For example:


·     There are many people who cannot safely be scanned with MRI (for example, because they have pacemakers), and also people who are too big to be scanned.

·     There are many claustrophobic people in the world, and being in an MRI machine can be a very disconcerting experience for them.

·     The machine makes a tremendous amount of noise during a scan. The noise sounds like a continual, rapid hammering. Patients are given earplugs or stereo headphones to muffle the noise (in most MRI centers you can even bring your own cassette or CD to listen to). The noise is due to the rising electrical current in the wires of the gradient magnets being opposed by the main magnetic field. The stronger the main field, the louder the gradient noise.

·     MRI scans require patients to hold very still for extended periods of time. MRI exams can range in length from 20 minutes to 90 minutes or more. Even very slight movement of the part being scanned can cause very distorted images that will have to be repeated.

·     Orthopedic hardware (screws, plates, artificial joints) in the area of a scan can cause severe artifacts (distortions) on the images. The hardware causes a significant alteration in the main magnetic field. Remember, a uniform field is critical to good imaging.

·     MRI systems are very, very expensive to purchase, and therefore the exams are also very expensive.

The almost limitless benefits of MRI for most patients far outweigh the few drawbacks.



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