There are various techniques of ultrasound imaging, including:

• A-mode. Also called amplitude modulation. Recorded as a single line showing the time needed to reach the organ and return to the transducer, a small device that sends ultrasound waves through the body.
  
  
• B-mode. Also called brightness modulation. Recorded as variations in brightness and darkness.
  
  
• Gray scale. Demonstrates various organs in shades of white and gray. Shades vary according to the strength of the sound wave echoes. The strongest echoes are white and the weaker echoes are darkening shades of gray.
  
  
• Real-time imaging. Shows rapid multiple views of anatomical structures, simulating motion.
  
  
• Doppler imaging. Used to measure blood flow. A shift in frequency occurs when a sound wave is echoed from something that is moving. Using this, ultrasound can measure the velocity of what is being studied, such as blood flow in a blood vessel. Different rates of flow are displayed in different colors on the monitor. This may be used to diagnose and evaluate many conditions, including:
  
  
• Risk of stroke
• Blood clots
• Valve function and defects
• Blocked arteries
• Stenosis (narrowing) of an artery
  
  
• Echocardiogram. Shows heart anatomy and function.
  
  
• Internal ultrasound. These tests are minimally invasive. The transducer in inserted into the body to obtain more detailed images. Forms of internal ultrasound include:
  
  
• Transesophageal echocardiogram (TEE). Insertion of a flexible, tube-like probe into the esophagus to view the heart. The patient typically receives a sedative and anesthetic.  The heart chambers and valves can be visualized better with this minimally invasive procedure.
  
  
• Transrectal ultrasound (TRUS). Insertion of a probe into the rectum to view the prostate.
  
  
• Transvaginal ultrasound (TVUS). Insertion of a probe into the vagina to view the uterus and ovaries.
  
  
• Intravascular ultrasound (IVUS). Attachment of the ultrasound transducer to a catheter, which is threaded through a blood vessel to view the internal structure of the vessel or the heart.