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New MRI Machines
 as your doctor ever ordered an MRI for you and when you arrived at the clinic you found that you were too claustrophobic or too large to fit in the narrow tube of the machine? Technology has resolved those problems with the new “Open” MRI machines.
MRI stands for Magnetic Resonance Imaging, a technology that
produces extremely detailed images of soft tissue, muscles, nerves and bones through the use of a powerful magnet, radio waves, and computer technology. A transmitter sends radio-frequency energy into the body, the magnetic resonance occurs in the water protons, and the receiver picks up the radio frequency magnetic fields from the protons. Gradient coils are used to make the magnetic field vary across the body. By analyzing the radio frequencies coming from the body, the computer can determine where in space the protons are, which is all that is needed to construct an image.
MRI is a safe diagnostic procedure. The patient experiences no physical sensations, however, certain scans increase body temperature in larger patients. Large units and high magnetic fields produce a banging noise. Low field magnets produce a faint knocking sound. The high resolution of the images assists the doctor in accurately diagnosing conditions without surgery or radiation. It can often find problems which other techniques such as x-ray and CT
(computerized tomography) can’t. However, due to the length of time required for abdominal studies, requiring patients to hold their breath, results are not always diagnostic on large patients.
The previous design has a round or oval opening 2 feet high. The opening is limited and the enclosed space is very uncomfortable for patients who suffer with claustrophobia. Patients who are very large find themselves wrapped up and stuffed into a very confining tunnel. Once in the machine, a patient is not able to get out by themselves. This feeling of helplessness adds to the claustrophobia, which can be very disturbing. MRI machines make a loud knocking noise from the magnetic coils changing pulse direction. Some patients find a mild dose of Valium, and/or a blindfold as well as verbal contact with the operator helps them cope with these feelings. Some clinics offer a rubber bulb connected to the machine which can be squeezed to notify the technologist of panic. The patient be removed from the machine promptly. It is said that this design can accommodate patients up to 350 pounds but patients 50 pounds less have had difficulty squeezing in. Scans generally take 30-60 minutes.
The new design is open on three or four sides which eliminates the claustrophobic feeling. It also allows more room to accommodate large patients. There
are between 18-20 inches between the table and the magnet. The open MRI is supposed to hold patients up to 450 pounds, depending on body build. Instead of a patient being inserted head first into a tube, the patient can slide in from the side. The patient can see their surroundings while the scan is being performed. For patients who are still fearful, they can even have someone sit nearby. An open MRI with low field magnetic strength can produce less detailed images. There is little or no difference in the diagnostic quality of images from a mid field magnetic field open machine as compared to a closed machine.
For anyone who is not familiar with MRIs, you need to lie still on the table of the machine. Different coils (or sensors) are used for different body parts. The coil is wrapped around the area being scanned (ie, head, knee, neck) and the patient is then put into the machine. This can also contribute to the feeling of claustrophobia. In some procedures, a contrast agent is injected into the blood stream to enhance the quality of the images produced. Patients may eat normally and go about their daily routine before and immediately after the exam. Scrubs or a gown will be provided or you can wear your own loose clothing.
Because of the magnetic field around the machine, patients are asked to leave metal or magnetic items in a locker provided outside the scan room. Patients will be asked a series of questions to ascertain a need for any precautions. Pacemakers, cochlear implants, neuro Stimulators, aneurysm clips, surgical staples, possible metal foreign objects in the eye and shrapnel may require special precautions.
The technologist are trained to ask appropriate questions regarding a patient’s medical history. It is imperative to answer honestly to avoid burns or injuries that can occur. Patient’s with implants should provide a card from the manufacturer identifying their implant. Surgeons provide these cards to patients receiving implants. Recent implants are usually surgical steel or titanium which are manufactured with MRI in mind and are not made of ferrous material. If the technologist or physician ascertains that the patient is not safe to go into the machine the exam will not be done.
With today’s technology there is no reason why patients of all sizes couldn’t have the exams done. Most facilities are accommodating and will make every effort to provide the scans a patient needs. Sometimes alternative exams can be done if a patient proves to be extremely claustrophobic. A patient should not let fear or nervousness prevent them from seeking good medical care.
Not all states/provinces have open MRI machines. If you are a large patient and/or claustrophobic and your doctor mentions an MRI you might want to ask him to locate an open MRI center. You can also locate them by doing a computer search for ‘Open
MRI’.
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