Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is a test that provides pictures of structures inside the body. It produces these images using a magnetic field and pulses of radio wave energy. When the area being studied is surrounded by the magnet, water molecules move in the body. A computer picks up the movements and converts them into pictures. An MRI does not use X-rays to create images. Sentara offers several types of MRIs to meet the exact needs of the patient and referring physician.
About MRI Scans
MRIs can determine the presence of certain diseases that other imaging methods—such as X-ray, ultrasound, or computed tomography (CT)—may not show as well.
- Tissues and organs that contain water provide the most detailed MRI pictures, while bones and other hard materials in the body do not show up well on MRI scans.
- Because of the strong magnetic field, it is very important for us to know if you have any metal in or on your body before your MRI scan is performed.
What can an MRI be used to evaluate?
Physicians order MRI scans to obtain information about many organs and areas of the body including: the brain and spinal cord; organs of the chest, abdomen and pelvis; reproductive organs in the male (prostate and testicles) and the female (uterus, cervix and ovaries); pelvic and hip bones; breasts.
Physicians use the MRI examination to help diagnose or monitor treatment for conditions such as:
- Stroke, headache, memory loss/dementia, seizures, multiple sclerosis,spine disorders and other diseases of the nervous system
- Coronary artery disease and heart problems
- Causes of pelvic pain in women, such as endometriosis
- Diseases of the liver
- Conditions involving the bile duct, gallbladder and pancreatic ducts
- Breasts, breast cancer and implants
- Spinal abnormalities
- Liver cancer and liver disease
- Ligament evaluation in body parts containing small joints, such as the hand, wrist, ankle and foot
- Disc herniation
- Heart disease
- Chest, abdomen and pelvis, kidney, spleen pancreas and adrenal glands
- Brain structure
- Orbit, pituitary, inner ear and cranial nerve imaging
- Pelvic and hip bones.
- Conditions involving the bile duct, gallbladder and pancreatic ducts (MRCP)
How do I prepare for my exam?
Generally, no preparation is necessary for an MRI scan. Speak to your physician about eating and drinking before the exam.
It is important for us to know if you have any metal or implanted devices in your body before your MRI scan is performed. The MRI uses a strong magnet that may cause heating or movement of certain metal objects or malfunction of devices in your body. Before you are scanned you will be asked questions regarding any metal or device to determine if it is safe for you to enter the MRI scanner. Occasionally, some piercings may have to be removed prior to your scan.
In most cases, an MRI exam is safe for patients with medically placed devices, except for a few types. Please speak to your physician if you have the following types, to determine if you can safely have an MRI exam, whether you are a patient receiving an MRI or a friend or family member who will be in the room.
- Pacemaker or Automatic Implantable Cardioverter Defibrillator (AICD)
- Some types of metal coils or stents placed within blood vessels.
- Implanted mechanical or electrical device (i.e. cochlear or stapes ear implant, magnetic dentures, spinal stimulator, etc.)
- Some types of brain aneurysm clips
Knowing the make and model of the implanted device is helpful. Also, let your physician know if you are claustrophobic, are pregnant or think you could be pregnant.
How is an MRI performed?
Patients will be positioned on the moveable examination table. Small devices that contain coils capable of sending and receiving radio waves may be placed over the area of the body part being imaged.
If a contrast material will be used in the MRI exam, an IV will be set up. Patients are then moved into the magnet of the MRI unit. If a contrast material is used, it will be injected into the intravenous line after an initial series of scans. Additional series of images will be taken following the injection.
During the exam, you will hear a rhythmic tapping sound. This is the normal sound of the magnetic fields as it scans.
MRI exams generally include multiple runs (sequences), some of which may last several minutes. An MRI exam normally takes between 30 and 60 minutes, depending on the part of the body scanned. MR spectroscopy, which provides additional information on the chemicals present in the body's cells, may also be performed during the MRI. Please remain still, typically only a few seconds to a few minutes at a time, while images are being recorded for the best image quality. For some types of exams, you may be asked to hold your breath to reduce movement. You’ll know when images are being recorded because of the tapping or thumping sounds that occur when the coils that generate the radiofrequency pulses are activated. You will be able to relax between imaging sequences. Some patients require sedation to complete an MRI without moving.
Are there risks?
The MRI examination poses almost no risk to the average patient when appropriate safety guidelines are followed. Although the strong magnetic field is not harmful in itself, some medical devices that contain metal or electrical components may malfunction or cause problems during an MRI exam. If you are a nursing mother and your study involves contrast material, please speak to your physician or the radiology department about when it’s safe to nurse again.
How will I find out the results?
Your MRI is interpreted by a subspecialized radiologist, a physician specially trained in reading MRI scans and in other diagnostic imaging tests. The radiologist will prepare a report for your referring physician. You should receive the results from the physician who sent you for your diagnostic study.
Physicians can order several different types of MRIs to evaluation a patient’s conditions. These include: