Open all the questions | Close all the questions
- Q: What is MRI, What is MRA?
MRI stands for magnetic resonance imaging, a type of diagnostic imaging that scans a part of the body (the brain, the abdomen or the lower leg, for example). MRI uses radio waves and magnetic fields as it scans parts of the body and generates signals that powerful computers can transform into amazingly detailed images of the human body. This technology has been safely used since 1981.
MRA stands for magnetic resonance angiography and is a group of techniques based on MRI to image blood vessels. Smart Choice MRI performs some MRA exams, but the most complicated procedures must be referred to locations with physicians available 24 hours a day.
Many times MRI can provide doctors with information about a child's condition that other types of imaging (X-rays, "CAT" scans or ultrasound) can't provide. Please visit our MRI vs CT vs X-Ray page for more information regarding the differences. MRI can be especially useful in looking at the brain, spine, soft tissue, muscle, ligaments, tendons, cartilage, bone marrow and blood vessels.
- Q: MRI vs CT
CT Scan does not show you tendons and ligaments very well at all; at least not yet. MRI is the best choice for that. Tendons and ligaments around the shoulder and knee are best seen by the physics used in MRI. This is due to the density of the tissues that compose the tendons and ligaments.
Spinal cord is best seen by MRI for the same reason. The density of the spinal cord and the composition of it is such that MRI physics can show it to us much better than CT.
There are also reasons why CT is the exam of choice over MRI. It is the preferred modality for cancer, pneumonia, and abnormal chest x-rays. Bleeding in the brain, especially from injury, is better seen on CT than MRI. But a tumor in the brain is better seen on MRI.
If you've been in an accident, organs can get torn or damaged. CT shows organ tear and organ injury quickly and efficiently. Broken bones and vertebral bodies of the spine are better seen on CT but injury to the spinal cord itself is displayed on MRI far better than CT.
CT is far superior at visualizing the lungs and organs in the chest cavity between the lungs. MRI is not a good tool for visualizing the chest or lungs at all.
MRI vs CT scan depends on what needs to be visualized and the reason you need the test. Radiologists are the doctors that specialize in reading images of the body and therefore know which test is best for showing anatomy according to the reason for the exam. Very experienced CT and MRI technologists will also know from working with Radiologists.
The difference in the way the images are produced in MRI vs CT is the physics involved. CT scan uses an x-ray beam that slices through you like a knife carving a spiral ham.
MRI ( magnetic resonance imaging) uses a magnetic field with radio frequencies introduced into it. When your body is placed inside the magnetic field, the molecules of water in your body (hydrogen molecules) will start to spin like a kid's top when he spins it. The top will begin to wobble as it slows down.
Your hydrogen molecules will start to wobble just like the top does at a certain rate of speed; the stronger the magnetic field, the faster they will wobble and the weaker the magnetic field, the slower they will wobble; it depends on the strength of the magnetic field.
Then a radio frequency is introduced into the magnetic field at the same rate of speed at which the "tops wobble" causing the wobbling tops and radio frequency to sing out together sharing the same signal frequency. (Thus the term resonance) That signal is used by the MRI computer to produce the image.
- Q: What if I am Claustrophobic?
Because MRIs can often be very intimidating to some patients, especially claustrophobic patients, Our Staff takes every step before and during your exam to help make you feel comfortable and lower your anxiety level. We always offer our patients the opportunity to see the scan room before their exam. Although we do not administer sedation to our patients, we often ask our patients to ask their referring physician for a mild sedative if they think the MRI exam will be difficult to complete due to claustrophobia. If a Closed MRI does not work for you, we do offer Open MRI options which our more sensitive patients never have problems completing the exam with.
- Q: A list of contraindications to having an MRI including pacemakers, defibulators, etc.
While MRI is an extremely safe test there are certain individuals that would be excluded, due to the magnetic strength of the machine. Some absolute contraindications would include:
-Ferromagnetic Cerebral Aneurysm clips (Clips prior to the MRI safe Titanium clips)
There are some other surgical implants and implanted mechanical devices that may be contraindications, and with the guidance of our expert Radiologists and expert staff, we can help determine the safety of your implant. Some surgeons will give you a card with MRI safety information listed so please bring this with you or let our staff know about these implants prior to your appointment so they can obtain the surgical notes to determine the safety of your implant.
If you ever had metal fragments in your eye that was not removed by a doctor, please let our staff aware before your scheduled appointment. They can coordinate an X-ray exam of your eyes to clear you for your MRI visit.
- Q: What body parts can the MRI scanner evaluate?
MRI is used by physicians to evaluate many different body parts. The most commonly examined body parts are the head, neck, back, shoulder, abdomen, pelvis, elbow, knee, ankle, foot, blood vessels and more. Unlike CT, MRI is most commonly used to distinguish soft tissues such as the brain, spinal cord and joint structures.
- Q: How long does the MRI exam take?
Although exam times differ from patient to patient, plan on spending around an hour at the MRI clinic. Scheduling will take about 10 minutes, unless you come with your scheduling forms filled out. After your forms are completed, the MRI technician will have you change into MRI safe clothing and have you place yourself on the MRI scanner. Depending on the area you are having scanned, MRI scan times vary from 25-45 minutes. Scan sequences last between 2-6 minutes and the tehnician will allow you to move in between the sequences if you need to readjust.
- Q: Are there any special preparations/restrictions for MRI exams?
- Q: Why is it so important to remove any metallic objects before I enter the MRI scanning room?
Because MRI uses strong magnetic fields, any metal or metalic object is hazardous to have in the scan room. Our MRI technologists and MRI staff will ask you safety questions regarding metal from previous surgeries and any other implants you may have. Please visit our Special Concerns page if you would like to know more.
- Q: What does the MRI scanner look like?
The look of a scanner depends on a number of variables including the type of scanner and the manufacturer. There are two types of MRI scanner options that we offer our patients; Closed MRI and Open MRI.
- Q: What does an Open MRI look like?
If you would like to see what our Open MRI scanner looks like, please visit our Open MRI page.
- Q: Will there be a problem if I have had surgery in which metal has been implanted?
During your scheduling, our Staff will ask you about any previous surgeries and any medical implants. Please be sure to inform your technologist of any prior surgeries. For a list of MRI safety requirements, please visit our Special Concerns page.
- Q: Is there any risk in having an MRI?
Because MRI uses low-energy, non-ionizing radio waves, there are no known risks or side effects. In fact, since the technique uses no radiation, it can be repeated with no known adverse effects. While there are no known hazards, MRI is not proven to be safe during pregnancy. If a pregnant woman must undergo an MRI, she will be asked to sign a special consent form. Please check our MRI During Pregnancy page for more information. The magnet at the center of the procedure may affect, or be affected by, any person fitted with a pacemaker, hearing aid, or other electrical device. People with such devices should advise the physician or technician. They are generally advised not to have an MRI. If you are concerned about an implant that you have or any previous surgeries where metallic objects were implanted, please check our Special Concerns page for a more detailed explanation of MRI safety.
- Q: MRI During Pregnancy?
- A: MRI is considered a safe test, and there is no ionizing radiation used. However, conclusive evidence showing how safe MRI is for pregnant women and the fetus is not yet available. MRI is generally not preformed during the first twelve weeks of pregnancy (first trimester). Generally, we do not perform MRI on pregnant wowen, unless there is a strong medical indication. Prior to the test you may want to consult with your obstetrician & the radiologist.
- Q: What are the noises associated with MRI exams?
Because the scanner works with large amounts of magnetic energy, there is some lost energy that we hear as sound. The sounds are usually described as loud buzzing and knocking and samples can be heard in our MRI Scan Sounds section.
- Q: Why does a traditional open MRI scan take so much longer than closed MRI?
Exam times depend on several factors including MRI scanner field strength. Generally, Closed MRIs have a much higher field strength and therefore exams average around 35 minutes. Open MRI scanners have lower field strength and therefored and exams average around 45 minutes. Open MRI exams are usually reserved for patients who are Claustrophobic or have problems fitting comfortably in the Closed MRI.