Magnetic Resonance Imaging (MRI) uses magnetic field energy, rather than X-ray radiation, to provide an unparalleled view inside the human body.
A High-Field MRI scanner is a large machine with a horizontal tube or “bore” running through the magnet from front to back. A Low-Field scanner is more of an open style magnet. The patient, lying on his or her back, slides into a special table. The largest and most important component in an MRI system is the magnet, which is rated using a unit of measure known as a Tesla. The MRI magnets in use today are in the 0.3-Tesla to 3.0-Tesla.
ProScan Imaging offers: High-Field MRI and Open MRI.
While the scan is in progress, the MRI system goes through the patient’s body point by point, building up a two- or three-dimensional map of tissue types. It then integrates all this information together to create 2-D or 3-D models of the scanned body parts.
Common uses of MRI imaging include diagnosing infections in the brain, spine, or joints; visualizing torn ligaments, shoulder injuries, and tendinitis; evaluating soft-tissue masses, cysts, and tumors; and diagnosing strokes and multiple sclerosis.
High-Field MRI:
The most powerful type of MRI scanner, offers a higher magnetic field strength. This generally means shorter scan times for the patient.
Open MRI:
This MRI has an open design that meets the needs of claustrophobic, pediatric, and larger patients. Open systems also are quieter and can be more comfortable.
Preparation
We encourage you to come to your appointment in comfortable loose fitting cotton clothing without metal fasteners or other metal lining. Many of the popular brands of sportswear have sweat wicking or antimicrobial properties that rely on a very thin metal mesh woven into the fabric, making them a poor choice to wear for your MRI. You may be asked to change at the site into a gown or medical scrubs for your exam. Unless you are told otherwise, you may follow your regular daily routine and take medications as usual.
What to Expect
As an added safety precaution before your MRI scan, your MRI technologist will review MRI safety precautions with you by discussing your responses on the safety screening form you filled out, and also scan you with a Mednovus Safescan Scanner or other similar device to determine that you have no metal on your body that will affect the safety of the MRI scan.
This new technology does not require patients to change into gowns before undergoing their imaging procedure. The Safescan Scanner detects any ferrous metal in your body. At locations without the Safescan Scanner, patients must change into gowns before the start of their procedure.You will be asked to fill out a safety screening form prior to being taken back to the scanner.
The technologist will walk you in and explain to you the type of scan you are having. If the study is ordered with contrast, the contrast is usually injected half way thru the scan after pre-contrast images are taken. At some sites the patient is connected to a power injector that will allow the contrast to be injected without the technologist going back in the room, but for many scans the tech comes into the exam room half way thru the scan – pulls the patient out of the scanner and injects them with contrast and then completes the study. The MR machine makes a noise that sounds like a continual, rapid hammering. You will be given earplugs or music headphones to muffle the noise.
MRI scans require patients to hold very still for extended periods of time. Your technician will talk to you through the exam and you will have a call bell to squeeze if you need immediate attention Now is your time to simply relax. In fact, many people fall asleep while being scanned.
MRI exams typically range in length from 20 to 30 minutes, although some procedures may take longer. Even very slight movement of the part being scanned can cause much distorted images that will have to be retaken.
Contrast
MRI and CT may require injectable contrast solutions, or dyes, for certain procedures. MRI contrast works by altering the local magnetic field in the tissue being examined. Normal and abnormal tissues respond differently to this slight alteration, giving us differing signals. These varied signals are transferred to the images, allowing us to visualize many different types of tissue abnormalities and disease processes better than we could without the contrast.
Magnetic Safety
Although there is no risk of radiation exposure from using MRI, we must take critical precautions while in the MRI suite because the extremely strong magnet will attract any metal objects taken into the scan room. For example, paperclips, pens, keys, scissors, money clips, or any other small objects can be pulled out of pockets and off the body.
Because they can interfere with the magnetic field of the MRI unit, metal and electronic objects are not allowed in the exam room. Strict precautions are taken prior to allowing a patient or support staff member into the room; he or she must first remove all metal objects and jewelry. Jewelry and other accessories should be left at home if possible, or removed prior to the MRI scan. We often let patients keep their wedding rings on after scanning them with the mednovus scanner.
Items not allowed include:
- Jewelry, watches, credit cards and hearing aids, all of which can be damaged
- Pins, hairpins, metal zippers and similar metallic items, which can distort MRI images
- Removable dental work
- Pens, pocketknives, and eyeglasses
- Body piercings and jewelry
You should tell the technologist if you have medical or electronic devices in your body, because they may interfere with the exam or potentially pose a risk.
Examples include, but are not limited to:
- Artificial heart valves
- Implanted drug infusion ports
- Implanted electronic devices, including cardiac pacemakers
- Artificial limbs or metallic joint prostheses
- Implanted nerve stimulators
- Metal pins, screws, plates, stents, or surgical staples
Patients who might have metal objects in certain parts of their bodies, such as metallic fragments, may also require an X-ray prior to an MRI. Inks used in tattoos may contain iron and could heat up during MRI, but this is rarely a problem. Tooth fillings and braces usually are not affected by the magnetic field, but they may distort images of the facial area or brain, so the technologist should be aware of them.
Most orthopedic implants are fine because they are firmly embedded in bone. Each time we encounter patients with an implant or metallic object inside their body, we investigate thoroughly to make sure it is safe to scan them. There is usually an alternative method of imaging we can use to help them. Patients who have certain types of implants, metallic fragments in the eyes, pacemakers, aneurysm clips, or some dental implants cannot be scanned.
Women should always inform their physician and the MR technologist if there is any possibility that they may be pregnant. Pregnant patients should discuss safety concerns with our imaging centers in advance of their appointment.
Advantages of MRI
There are no known biological hazards to humans from being exposed to magnetic fields of the strength used in medical imaging today. MRI systems do not use radiation, and MRI injectable contrast has a very low incidence of side effects.
MRI can image in any plane of the body, while CT is limited to one plane, the axial plane (using a loaf-of-bread analogy, the axial plane would be the way a loaf of bread is normally sliced). An MRI system can create axial images as well as images in the sagittal plane (think of slicing the bread side-to-side lengthwise) and coronally (think of the layers of a cake) or any degree in between, without the patient ever moving.
Common uses of MRI include:
- Diagnosing infections in the brain, spine, or joints
- Visualizing torn ligaments in the wrist, knee, and ankle
- Visualizing shoulder injuries
- Diagnosing tendonitis
- Evaluating masses in the soft-tissues of the body
- Evaluating bone tumors, cysts, and bulging or herniated discs in the spine
- Diagnosing strokes in their earliest stages
- Diagnosing multiple sclerosis (MS)
- Diagnosing tumors of the pituitary gland and brain
Frequently Asked Questions
1. If I have metal objects in my body, can I still have a MRI?
Patients who have implants, metallic fragments in the eyes, pacemakers, aneurysm clips, or some dental implants may not be able to be scanned. You should tell the technologist if you have medical or electronic devices in your body. ProScan will evaluate each patient prior to being scanned. Most orthopaedic implants are fine because they are firmly embedded in bone.
2. I am a large person; will I fit into the MRI unit?
Some ProScan Imaging centers can accommodate patients weighing up to 550 pounds. Please contact each imaging center directly to learn about its equipment capabilities.
3. I am claustrophobic and need an MRI scan – what can I do?
At ProScan, we are skilled at working with claustrophobic patients. We suggest you obtain a prescription from your doctor for a sedative and make transportation arrangements. We also have open MRIs at some of our centers that give patients a sense of being less enclosed. Our technologist can supply you with covers for your eyes, headphones, and if you like, you can even have a family member sit next to you while you are scanned (providing he or she has no metal in or on their body).
