Have you ever been diagnosed with back pain or a sports-related injury while living in Atlanta? An MRI exam was probably ordered by your orthopedist, chiropractor or general doctor to assess the damage to the particular body part in question. To know how to prepare for an MRI exam, you should understand what an MRI is and how it works.
MRI, or Magnetic Resonance Imaging, is a versatile and unique tool that doctors use to help diagnose spinal or joint injuries by imaging the soft tissues, muscle, ligaments, tendons, fat, fluid deposits, spinal cord, intervertebral discs, vertebrae, spinal nerves and more. An extraordinary amount of information about the inside of your body is revealed through these detailed images. MRI is also used to image the blood vessels, the heart, all the organs in your body and often the brain and neural tissue.
What is MRI and how does it work?
Magnetic Resonance Imaging uses a strong magnet and radio frequency waves (the resonance) to create images in different planes. Numerous cross-sectional images or slices are produced without the use of harmful radiation. When your body is placed in the powerful magnetic field, your hydrogen atoms line up like rows of small magnets. These atoms are then subjected to pulses of RF waves, the loud knocking noises you hear during your scan. The pulses knock the atoms out of alignment, and as they fall back into place, they produce a radio signal that is detected by the special camera placed around, on or under the specific body part that is imaged.
Different tissue types fall back into alignment at different rates and are measured by the computer, which then produces a picture in a black to white scaled image. Areas that have large amounts of hydrogen, such as the brain, will give a bright image, while areas of no hydrogen, such as bone, will give a black image. Areas in between are shown in a grey scale.
Imagine your body as a loaf of bread. Take a piece out and look at it sideways; that is how the technologist and radiologist sees the pictures, and in three different planes: left to right, bottom to top and back to front.
Who reads MRIs?
A specialty medical doctor called a radiologist reads the exam and relates abnormalities that show up in the images. Radiologists also specialize in different body parts. Neuroradiologists read the brain and spinal exams. Musculoskeletal radiologists read joint and muscle exams. Other subspecialties include gastrointestinal, breast imaging, cardiovascular and pediatric radiology.
How to prepare for an MRI exam
When you check in to the imaging center or hospital, you will be given an MRI check list or screening form to make sure that you are MRI safe. There are several contra-indications for having an MRI exam. If you have a pacemaker in your chest or aneurysm clip in your brain, you will not be able to have the exam. If there is any ferrous metal in your body, such as metal shavings in the eyes from welding work, or bullets and buckshots, you will probably be denied or heavily screened before the technologist will proceed with the exam. Usually any metal from joint implants, such as screws, pins or plates, are made from titanium and thus non-ferrous, non-magnetic and considered safe for MRI.
You will then be asked to change into a gown or scrubs depending on the body part imaged. Your valuables will be placed in a locker. Remember, you will be entering a room with a high field magnetic; if you have anything metal in your pockets, such as keys, knifes or hairpins, they can become flying projectiles. If you take your wallet into the room, the magnet will erase all of your credit cards too.
The technologist will be your guide through the process and explain everything to you. You will lie down on a table and then be placed into the bore of the magnet or scanner, which is usually four feet long. The body part that is imaged is usually in the middle of the scanner. If you are having a knee MRI, then only half your body will actually be inside the scanner. Some people are claustrophobic and need medication prescribed by the ordering doctor before the exam, so they can relax comfortably and hold still during the scan. There is no other indication for pre-exam preparations such as dietary restrictions. Most importantly, try to stay still while you hear the loud knocking noises in the machine. That is when the actual images are being acquired by the scanner.
Questions to ask
According to Dr. Ho Lin, a radiologist at OutPatient Imaging (OPI) in Atlanta, when you are looking for a site to have your MRI, and you do have a choice, ask several questions before you decide.
1. Ask if the MRI machine is ACR (American College of Radiology) certified. The ACR approves accreditation after closely evaluating the qualifications of the technologists and radiologists, the adequacy of the equipment, quality of the images and procedural evaluations.
2. Ask if there is a radiologist on site and if he or she is board certified. Ask if your exam will be read by a fellowship trained sub specialty radiologist. This way a neuroradiologist will read your spinal MRI or a musculoskeletal radiologist will evaluate your knee MRI.
3. Ask how old the equipment is. Choose a site with newer scanners and with a high magnetic field, above 0.5 tesla for an open MRI and 1.5 tesla or higher for a closed magnet. Better detailed and accurate images are acquired in a higher field magnet.
Having an MRI does not have to be a trip into the unknown. Get all the facts, ask the right questions and you will be pleasantly surprised at how easy having an MRI exam can be.