About Magnetic Resonance Imaging
An MRI is a test the uses a magnetic field to image the body.
MRI is short for Magnetic Resonance Imaging. MRI is a very useful type of diagnostic imaging exam and can be used for a variety of reasons. MRI is very sensitive to changes in body tissue and has a very high resolution. This allows a radiologist to see changes that may not be visible in other imaging exams. MRI excels at imaging soft tissues such as internal organs, muscles, cartilage and the brain and spinal cord. It is also very sensitive to subtle changes in bones. While MRI is a very powerful and versatile technology, it is not used in all circumstances. Your doctor will let you know if MRI is the right exam for you.
MRI does not use radiation as CT scans and x-rays do. Instead, MRI creates images using a very strong magnet and radio waves. The images are cross sections like CT scans, but MRI can also take lengthwise images without the patient having to change position.
Some MRI scans require the use of a contrast medium called gadolinium. The contrast, which is given intravenously, highlights certain body parts so the radiologist can better see any abnormalities.
Conventional MRI machines have a donut shape with a tube that is usually about 3 feet in length. This exam causes anxiety for some people who are claustrophobic. If you know you are claustrophobic, please let our staff know at the time of scheduling. You may be given a mild sedative to help you relax during your exam.
Open-bore MRI has a shorter and wider tube, or “bore,” than a traditional MRI scanner.
Our open-bore MRI is about half the traditional length yet provides the same high field technology to achieve the same image quality. Since the tube is shorter, part of your body will be outside the scanner during your exam. For example, if your feet are being imaged, your head will be outside of the scanner. This may make the exam more comfortable for claustrophobic patients. With a wider opening (70cm or about the size of a hula hoop) and a weight limit of 550 pounds, this scanner allows us to offer MRI exams to larger patients who may exceed the size or weight limitations of a traditional MRI scanner.
Risks involved in an MRI
MRI uses a very strong magnet.
It could be dangerous to be in the magnetic field if you have any of the following:
- Aneurysm clips in the brain
- Implanted electronic devices such as nerve stimulators or medication pumps
- Metal fragments or splinters in the eye from grinding metal or welding
- Implants in the inner ear (cochlear)
Some MRI exams require the use of an intravenously given contrast medium. As with any other intravenously given substance, there is the possibility of a reaction. However, documented reactions to MRI contrast are very rare.
During the Exam
A MRI scanner has a donut shape and is about three feet long.
MRI scans vary depending on the area of the body being imaged and whether or not contrast or sedation is needed. However, here is generally what will happen:
- A technologist will ask you some safety questions.
- You will remove all metal and metallic objects, such as eyeglasses, belts, hair accessories and jewelry. You may also need to change into a gown. You may use a secure locker for your personal items during your exam.
- If you need contrast or sedation, a small IV will be placed in your hand.
- You will go to the exam room. The technologist will help position you on the MRI table. A device called a coil will be placed on or around the area being imaged. Padding may be used to prevent inadvertent movement.
- During the scan, which usually lasts 20-30 minutes, the MRI machine will make buzzing and banging sounds. You will be provided with earplugs or headphones to protect your hearing. It is extremely important not to move any part of your body during the MRI scan to avoid blurring the images.
- If an IV was placed in your hand, it will be removed after the exam is completed.
- If you changed into a gown, you will change back into your clothes.
- The technologist will not stay in the room during the scan, but you can speak with him or her throughout the exam by intercom.
- Some specialized exams may take longer than 20-30 minutes. If you require copies of your MRI images, please notify the technologist before your exam begins.
MRI Scans Requiring Contrast Medium
If your exam was ordered with contrast (gadolinium), scans will be taken both before and after your receive the contrast:
- MRI Scans Requiring Sedative
- Sedation must be given one hour before the exam is performed. Children under the age of 10 usually require sedation.
- Additional Measures for Children
- If the patient is a child, two adults may be in the MRI room with him or her.
After the Exam
You can return to your normal activities immediately after your MRI unless you received a sedative.
If you were sedated, you cannot drive after the exam.
A board-certified radiologist experienced in the interpretation of MRI scans will analyze the data and results from your exam. If the patient is a child, the exam data will be analyzed by a radiologist experienced in the interpretation of pediatric MRI scans. The results will be reported to your physician. Your physician will pass the results onto you.
During the exam, our radiologists and technologists will be happy to answer questions about the exam itself; however, they will not immediately provide you with the results of your exam.