Did you know that a magnet could help doctors diagnose problems within your body? Magnetic resonance imaging (MRI) gives clear, detailed pictures of a number of body structures including:
• Soft tissues near bones
• The cardiovascular system including the heart, aorta, coronary arteries and blood vessels
• Organs in your chest and abdomen including the liver, lungs, kidneys, spleen and pancreas
How an MRI Works
MRI uses radio frequency waves and a strong magnetic field. Inside the MRI machine is a large, powerful magnet that when activated creates a magnetic field. Once the magnetic field is generated, the hydrogen atoms within the body line in the direction of the magnetic field. Next radio frequency waves that work with hydrogen protons are pulsed toward the part of the body being examined. The pulses cause the protons to absorb the energy and start to spin. When the pulses are stopped, the protons go back to the way they were and release the stored energy. This gives off a signal that the machine picks up and sends to a computer, generating an image that doctors can use.
The power of an MRI machine is measured in tesla. You may hear references to a machine being a 1.5 or a 3.0 tesla machine. Generally, a higher number means the machine produces a stronger magnetic field and will provide better detail than a machine with a lower tesla number. Tenet Healthcare is acquiring advanced technology like this and has already placed 3.0 tesla MRI’s throughout their Florida region at Delray Medical Center, Palmetto General Hospital, and West Boca Medical Center.
Uses of MRI
MRI allows doctors to look deep inside the body without surgery. This technology has many uses including:
• diagnosing tumors,
• visualizing orthopedic injuries including torn ligaments and tendon damage,
• evaluating masses in soft tissue,
• diagnosing cardiovascular disease, and
• evaluating spinal and joint problems.
Special dyes or contrast agents may be used to improve the quality of the images. The contrast material is generally given through an intravenous solution during the procedure.
MRI isn’t for everyone. MRI should not be used during the first 12 weeks of pregnancy. Patients who have had cardiac surgery or who have metal implants such as implanted insulin pumps, artificial joints, surgical clips, metal stents and cardiac valve replacements may not be able to have an MRI because of the strong magnet used. In addition, anyone who has had metal pieces in the eye or eye socket should avoid an MRI.
An MRI Exam
An MRI exam is similar to a computed tomography or CT scan. You will lie on a table moving you into the machine, which has a large center opening that resembles a donut. The technician may use soft devices to help hold you in place to help ensure a good scan. The scan itself may take several runs in order to get the pictures your doctor needs. The exam will take about 45 minutes but more time may be needed depending on the type of exam you are having.
If a contrast material will be used to enhance the images, an intravenous (IV) line will be placed in your arm, and the medicine will be given through that line. The medicine used as a contrast agent can cause you to feel at first cool and then flushed. This is normal. You may have some bruising around the area where the IV is inserted. If you do experience nausea or pain let the technician know. Also in some rare instances patients have an allergic reaction to the contrast. If you have hives or feel itchy, tell the technician immediately.
During the MRI exam, you may feel slightly warm. This is a normal reaction to the test. Tell the technician if it becomes a problem. You will need to remain still when the computer is recording the images. You can relax between images.
An MRI machine makes loud thumping and humming noises. You may want to ask for earplugs to help reduce the noise. Some scanners have built-in speakers that allow you to listen to music during the exam.
Open MRI
For those who suffer from claustrophobia or those who are obese, open MRIs may be an option. This type of MRI is designed to make patients more comfortable during the procedure. A digital open MRI design allows the images to be stored electronically on a computer and can be sent in moments for your physician to review.