MRI myths and realities

By Joe Gallivan, R.T.(R)(MR)  |  5/6/2015

Magnetic Resonance Imaging (MRI) scans are used to diagnose a variety of medical conditions, including torn ligaments, spinal cord injuries and brain tumors.

MRI uses a powerful magnet, so it is important to keep metallic objects out of the scanning area. This is why access to the MRI scanning area is restricted, and all patients are screened to determine if they have metallic objects or implants that may place them at risk prior to their MRI exam. With that said, not all implants or metallic objects are dangerous. Here are some myths and realities to help you better understand what is safe for MRI.

Myth: I can’t have an MRI because I have metallic screws, plates or rods inside me from orthopedic/spinal surgery.

Reality: Fortunately, the majority of orthopedic devices used to care for patients can be safely scanned. This includes orthopedic joint replacements, orthopedic pins and rods and most hardware that is implanted in bone. Most patients wait 4 weeks after having an orthopedic or spinal implant before getting an MRI. This time allows the implant to fuse to the bone and develop scar tissue around the metal. In an emergency situation (such as stroke), some imaging centers can perform MRIs the day after a surgical implant as long as it is purely titanium or non-ferrous metal.

Myth: I can’t have an MRI because I have dental implants such as braces, fillings or bridges.

Reality: All patients with dental implants can have an MRI. They can even have an MRI the same day as implantation. As dental implants are securely anchored into the tooth or jaw, the MRI doesn’t have a strong enough attraction to dislodge them. If you have a partial plate or dentures, the MRI technologist may have you remove them depending on what kind of study you are having.

Myth: I can’t have an MRI because I have tattoos.

Reality: The only tattoos that are unsafe for MRIs are ones that contain ferrous metal flake in them, which are usually found in tattoos that were done in prison. Most professional tattoo parlors no longer use ferrous metal flakes in their coloring. If you have a tattoo with metal flake, it can be scanned. In this scenario, you would hit the panic button if you feel any warmth around the tattooed area. We would then slow the scan down and take breaks between sequences or put small ice packs on the metal flake tattoo.

Myth: I can’t have an MRI because I have piercings.

Reality: MRI techs are concerned for your safety first and foremost. That is why we prefer that you remove all metal piercings prior to your MRI scan. If a piercing cannot be removed, we suggest you talk directly to the Chief MRI technologist. Sometimes the placement of the piercing or the metal that the piercing is made of may not affect the MRI.

Myth: MRI exposes patients to high levels of radiation.

Reality: MRI does not use ionizing radiation like X-ray or CT, so the potential risks with radiation are avoided. Instead, MRI uses radiofrequency pulses to excite the hydrogen protons in the body and then measures the signal from the protons as they relax. MRI is thus a safe tool that can be used on people of all ages, including children and pregnant woman in their second and third trimesters.

Myth: I can’t have an MRI because I’m pregnant.

Reality: While there are no randomized trials proving safety, it is established practice to scan second and third trimester pregnant patients with serious medical conditions where MRI is the only tool that can diagnose the patient. Most facilities do not scan within the first trimester due to the rapid fetus development. We recommend that the patient contact the Chief MRI technologist who will consult with the radiologist and the referring physician to plan the protocol for the MRI (the OBGYN doctor may also be consulted for safety). The rule of thumb is “does the benefit of the MRI outweigh the risk?”

Myth: I can’t have an MRI because I’m claustrophobic.

Reality: Scanners have changed dramatically over the years. They are no longer 9 feet long and feel like a coffin. Most of today’s short bore MRI machines are 3.5 feet long and have an opening on both ends of 60cm-70cm. If you are worried about claustrophobia, inform the MRI tech before the exam. The tech will kindly support you and ease you through any fears.

Most of the time the MRI sequences are between 2-4 minutes long. The technologist will talk to you between each sequence (typically we run about 5 sequences per exam). The technologist will also arrange for his tech aide or a staff member to stay in the room with you during your MRI to hold your hand or comfort you during your MRI.

For extreme cases of claustrophobia, we can switch to faster sequences which last between 30 seconds and 1.5 minutes (we will run 4-5 fast sequences per exam). The fast protocol images aren’t as good as the standard images, but they are much better than Open MRI images.

Myth: An Open MRI is as good as a closed or short bore MRI.

Reality: A common complaint for patients having MRIs is a claustrophobic feeling upon entering the tube. Open MRIs or low-field MRIs were created to combat this feeling. It is appreciated that patients have options when it comes to scanner preference. Open or standing MRIs do not offer the same image quality as standard high field, short bore tube MRI machines. With Open MRIs or standing MRIs that have openings on the sides, the magnetic field is slightly broken and they aren’t as powerful. While you can get somewhat useful images with Open MRIs, having a standard short bore MRI is really the better option for good diagnosis.

Learn more about Imaging [link to http://www.healthquest.org/Imaging/Imaging.aspx ] and Health Quest Medical Practice Imaging Center in Kingston, which specializes in easing the fears of claustrophobic patients.