The magnetic resonance imaging (MRI) test uses a powerful magnetic field to create images of structures and organs within the body. It is a safe and usually noninvasive test that can help physicians diagnose a wide range of diseases and conditions without subjecting the patient to radiation.

An MRI works by placing the patient in a chamber surrounded by a magnetic field. The center (nucleus) of atoms in the patient’s body responds to the magnetic force in characteristic ways, allowing a computer to produce clear cross-sectional or three-dimensional images.

Sometimes MRI involves the use of a contrast medium that increases the clarity of the images by making the body’s tissues more responsive to the machine’s magnetic and radio waves. Contrast medium is typically provided through intravenous injection but in some cases, it may be swallowed in liquid form. If no contrast medium is used, the patient may complete the test without any needles.

MRI is often used to diagnose the following:

• Detection and staging of various forms of cancer
  
  
• Strokes and chronic disorders of the nervous system
  
  
• Brain abnormalities in patients with dementia
  
  
• Diseases of the pituitary gland
  
  
• Eye or inner-ear tissue abnormalities
  
  
• Damage from heart attack or heart disease, including vessel plaque and blockage
  
  
• Bone and joint damage, infections, injuries or degenerative disorders
  
  
• Functional disorders of internal organs
  
  
• Reproductive system and bladder problems

Conditions that affect women and can be diagnosed using MRI include:

• Disorders of the pelvis, hips and bladder. MRI frequently is the preferred imaging technique when diagnosing conditions in these areas of the body in both women and men. Unlike other imaging systems, such as computed axial tomography (CAT scan), MRI allows the physician to view an area of the body in multiple planes. This is especially valuable in imaging pelvic structures that are not clearly viewed.
  
  MRI also does not use radiation, which is an advantage when examining reproductive organs that are vulnerable to potential damage from radiation.
  
  Several studies have shown that MRI is an effective technique for diagnosing reproductive cancers such as those of the endometrium, ovaries and cervix.
  
  

  

• Breast disorders. Clinical trials are under way to determine the effectiveness of using MRI as a screening tool for breast cancer. An MRI can produce side-to-side, top-to-bottom and front-to-back images of the breast without exposing the patient to radiation. However, MRI cannot always distinguish between conditions that are malignant (cancerous) and those that are benign (noncancerous). In addition, MRI cannot detect microcalcifications in the breast. A mammogram continues to be the optimal imaging test for detecting the first signs of breast cancer.
  
  Special MRI machines are currently available in some medical centers that are designed for breast examinations. Research studies have shown that enhanced MRI may be an effective tool for early detection of breast cancer. It is becoming increasingly popular as an addition to mammography, particularly with high-risk women, such as those with a genetic link to breast cancer.
  
  MRI is also used to evaluate breast implants for possible leaks and ruptures and screen for abnormalities in dense breast tissue, which is often found in younger women.