MRI (magnetic resonance imaging) is a diagnostic tool that examines tissue water and fat. Unlike x-ray based techniques, MRI uses a magnet and radio waves to produce images of normal and pathologic tissues. The technique has proven very valuable for the diagnosis of a broad range of conditions in all parts of the body. MRI is being used to evaluate cancer, heart and vascular disease, stroke, joint, and musculoskeletal disorders.

MRI requires specialized equipment and expertise and allows evaluation of some body parts that may not be as visible with other radiology procedures.
MRI is a relatively safe imaging technique; however, it is not for all patients. The MRI staff carefully screens all patients prior to entry inside the MRI work area. Patients who have these situations may not be candidates for MRI: 

  • heart pace maker
  • heart pacing wires
  • implanted defibrillators
  • aneurysm surgical clips
  • cochlear implants
  • implanted tents units
  • implanted metal plates
  • bullets/shrapnel
  • obesity (over 300 pounds--most will fit depending on the type of exam)

Some tattoos and permanent eyeliner may cause discomfort. Most other surgical pins, screws, rods, artificial heart valves and vascular stents that have been in place six-eight weeks are okay. Dental work, braces, or other metal close to the area of interest will cause image artifacts. Any object that might degrade the MRI images will have to be removed (such as hairpins, jewelry, medication patches, eyeglasses, hearing aids, and any removable dental work).

What to Expect

The MRI staff will ask about drug allergies and document a medical/surgical history. If there is a chance of pregnancy, the MRI technologist should be informed. Some patients may require a mild sedative to overcome claustrophobic feeling. This should be obtained from the referring physician prior to arrival. If sedatives are used, the patient will need someone to drive them home. Please ask the staff any questions that you may have.

How does MRI work?

MRI is a unique imaging method because, unlike the usual X-Ray, Nuclear Medicine, and even CT scanning, it does not rely on ionizing radiation. Instead radio waves are directed at protons, the nuclei of hydrogen atoms, in a strong magnetic field. The protons are first excited and then relaxed emitting radio signals, which can be computer processed to form an image. In the body, protons are most abundant in the hydrogen atoms of water - the "H" of H 2 O -- so that an MRI image shows the differences in the water content in body organs or tissues (even different types of tissue within the same organ). For example the gray and white matter of the brain can easily be distinguished with MRI. Each MRI procedure has its own protocol which demonstrates contrast differences and shows a cross-section image of the body part.

How is the MRI exam performed?

The technologist will complete a medical history form and answer any questions. The patient will lie on a sliding table and be positioned comfortably usually on their back. Patients are offered earplugs to reduce the loud tapping or knocking noise during the imaging phases. If indicated IV contrast is injected via small needle in a vein in the hand or lower arm. MRI equipment (coil) is place near the body part or region of interest. The MRI table will slide into the bore or opening in the magnet. The patient will be able to communicate with the technologist by intercom. It is important that the patient follow any instructions and lie still during the imaging phase. Typically, most procedures last 30 to 45 minutes depending on the number of images needed. Patient must bring a list of all medications.

The most common uses of MRI Imaging:

  • Detecting brain and other tumors of the head and neck
  • Locating brain damage or bleeding within the brain
  • Cause of hearing or vertigo problems
  • Evaluation of carotid arteries, heart, aorta, and other blood vessels in the abdomen and lower legs
  • Evaluation of arterial aneurysm
  • Diagnosing disease of the kidneys, liver, spleen and pancreas
  • Spinal and joint problems (arthritis/herniated disc)
  • Sport related injuries
  • Evaluation of infection or metastatic process of bone and joints

What are the Benefits VS Risks?


  • Images of the soft-tissue structures of the body - such as the brain, heart, lungs, liver and other organs--are clearer and more detailed than with other imaging methods
  • MRI images can help physicians evaluate the function as well as the structure of many organs
  • The detail of MRI images makes MRI an invaluable tool in early diagnosis and evaluation of tumors
  • MRI contrast material is less likely to produce an allergic reaction than the iodine based materials used for conventional x-rays and CT scanning
  • MRI enables the detection of abnormalities that might be obscured by bone with other imaging tools
  • MRI provides a fast, noninvasive, alternative to x-ray angiography for diagnosing problems of the heart and cardiovascular system
  • Exposure to radiation is avoided


  • Patients with a pacemaker can not enter the strong magnetic field
  • Other implanted metal devices may be affected by the strong magnetic field. Examples heart stents, pacing wires, implanted defibrillators, cochlear implants, and artificial heart valves
  • MRI is generally avoided in the first 12 weeks of pregnancy. Doctors usually use other methods of imaging, such as ultrasound, unless there is a strong medical reason

Picture Archival & Communication System (PACS)
This technology allows images to be electronically captured, stored and transmitted--all without film.

PACS makes high-quality MRI, CT, X-ray and ultrasound pictures immediately available by computer. That means doctors can readily view any images the patient has had taken at any West Tennessee Healthcare facility. Patients no longer need to carry X-rays from place to place. In addition, PACS gives such clear images that doctors believe it results in a better, more accurate diagnosis.

West Tennessee Healthcare (WTH) does not exclude, deny benefits to, or otherwise discriminate against any person on the grounds of race, color, national origin, age, religion, disability, Limited English Proficiency or sex, including discrimination based on gender identity, sexual orientation, sex stereotyping or pregnancy in admission to, participation in, or receipt of the services and benefits under any of its programs and activities, whether carried out by WTH directly or through a contractor or any other entity with which WTH arranges to carry out its programs and activities.

For further information about this policy, contact Amy Garner (731) 541-9914.