What You Should Know About MRI
X-rays are standard when it comes to photographic images of the human body, but many people are less familiar with Magnetic Resonance Imaging (MRI). MRI scanners are large machines with a large circular shaped outer structure with a magnet inside, and a table that patients lay on to enter the scanner through a tunnel-shaped opening. Using radio waves, MRI gathers detailed photographs of the human body that show up as gray scale images on a computer. The pictures can be used to develop 3-D images of the body, helping medical providers better identify issues and injuries.
Molly Casselman, BS, RT (R) (MR) is the MRI Manager for OrthoCarolina and understands that having an MRI can be worrisome for patients who may not understand what happens during the test. She answered some of the most common questions about the process and technology:
1. As an expert, how would you explain Magnetic Resonance Imaging?
MRI uses a very strong magnetic field to align the atoms in the body and a variable magnetic field that causes them to resonate and flip their spins. When the field is turned off the protons return to their normal spins at different rates depending on the tissue type.
2. How is MRI different from X-rays?
X-rays are primarily used to evaluate bones and soft tissue. MRI uses no radiation, but rather a magnetic field and offers a much more detailed image where muscles, tendons, ligaments, soft tissue, and bone can be evaluated.
3. What might someone have an MRI for?
Patients can have an MRI scan to diagnose many different issues. Some of these can include:
- Joint abnormalities caused by traumatic or repetitive injuries, such as torn cartilage or ligaments
- Disk abnormalities in the spine
- Bone infections
- Tumors of the bones and soft tissues
- Brain Tumor
- Internal organ abnormality: kidney, liver, pancreas, uterus, etc
- Disorders of eye and inner ears
- Aneurysm of cerebral vessels
- Infection in the soft tissue
4. If someone has an implant or pacemaker can their MRI be affected?
Yes it can. The screening process is VERY important for MRI patients. There are certain implants that may not be able to go into the magnetic field, namely aneurysm clips, spinal cord stimulators, cardiac pacemaker, cardiac defibrillators and certain eye/ear implants. Each patient must complete a clearance form which the MRI tech reviews along with the patient to make sure that the patient is safe to go into the MRI scanner. There are a lot of implants that are perfectly safe for MRI and there are even MRI compatible pacemakers and aneurysm clips that can be scanned, but we still must be wary of ALL implants as to not cause harm to anyone.
5. What do patients wear during MRI?
Depending on what part of the body is being scanned, some patients do not have to change into a gown (they will have to empty their pockets). If a patient has clothing with a lot of snaps or zippers in the area of interest then we would have the patient change into a gown or shorts. Most women are asked to remove their bra due to the underwire and clips in the back. Metal on clothing such as zippers or snaps can cause a black void on the image if in the area being scanned.
6. Some people say that having an MRI is like being in a tunnel with loud banging. From your perspective is that accurate?
Yes, that is fairly accurate! The MRI is very noisy, but some people actually find the consistent noises relaxing and can even fall asleep. For claustrophobic patients, we understand the unit can be a bit scary. We can offer music, a washcloth over the eyes, and can also check in after each scan to help ease the patient’s anxiety. Our newest unit is at our Ballantyne office and is a wide bore unit which offers a more spacious tunnel for patients that are claustrophobic.
7. What ARE the noises you can hear during MRI?
The gradient magnetic field is the main source of acoustic noise. The noise occurs during the rapid change of currents within the gradient coils. Patients are always provided hearing protection in the form of earplugs or headphones to block the noises during the MRI.
8. In your opinion has the technology changed much in recent years?
I think that the technology used in MRI is constantly evolving. Our newest unit in Ballanytne offers a silent scan technology which quiets the machine for certain sequences. This newer unit also offers MARS which stands for “Metal Artifact Reduction Sequence”. This allows us to image joint replacements whereas on the other units, imaging a joint replacement is nearly impossible due to the metal artifact.
9. What are the risks of MRI? What should people know? MRI is noninvasive and since no radiation is used during an MRI there is little risk as long as patients are screened properly prior to entering the magnetic field.