Ultrasound for Cancer

What is an ultrasound?

An Ultrasound technique is a non-invasive diagnostic technique (the skin is not pierced) that is used to determine structures of soft tissue such as muscles, blood vessels and organs. Ultrasound uses a transducer, which sends out ultrasonic sound waves at too high a frequency to be heard. The ultrasonic sound waves pass through the skin and other body tissues to the organs and structures inside when the transducer is positioned at certain positions and angles. The sound waves bounce like an echo off the organ and return to the transducer. The transducer absorbs the reflected waves, which are then transformed into an electronic representation of the organs or tissues under analysis by a computer.

Various forms of body tissue influence the rate at which sound waves fly. Sound passes through bone tissue the fastest and moves through the air the most slowly. The transducer describes the speed at which the sound waves are transmitted to the transducer, as well as how much of the sound wave returns, as various types of tissues. A clear conductive gel is placed between the transducer and the skin to enable the transducer to pass smoothly over the skin and to remove air between the skin and the transducer for better conduction of sound. Blood flow can be measured by using an alternative mode of Ultrasound technology during an ultrasonic procedure. An ultrasonic transducer able to assess blood flow contains a Doppler probe.

Inside the transducer, the Doppler probe measures the vessel’s velocity and direction of blood flow and makes the sound waves audible. Ultrasounds are used to view internal organs as they function (like a live TV broadcast in “real-time”), and to measure blood flow into different vessels. Ultrasound tests are also used to test various areas of the body, including the heart, breasts, female pelvis, prostate, scrotum, thyroid and parathyroid glands and the vascular system. Ultrasounds are conducted during pregnancy to determine fetal growth. Ultrasound technological advances now provide images that can be viewed in a three-dimensional (3-D) and/or four-dimensional (4-D) perspective. The added 4-D dimension is motion, so it is a moving 3-D view.

What are the different types of Ultrasound procedures?

Different Ultrasound techniques exist for different conditions. Examples of some of the more common types of Ultrasound examinations include the following:

Doppler ultrasound: Used to see structures inside the body, while evaluating blood flow at the same time. Doppler Ultrasound can determine if there are any problems within the veins and arteries.

Vascular ultrasound: Used to see the vascular system and its function, including the detection of blood clots.

Echocardiogram: Used to see the heart and its valves, and to evaluate the effectiveness of the heart’s pumping ability.

Abdominal ultrasound: Used to detect any abnormalities of the abdominal organs (i.e., kidneys, liver, pancreas, gallbladder), such as gallstones or tumours.

Renal ultrasound: Used to examine the kidneys and urinary tract.

Obstetrical ultrasound: Used to monitor the development of the foetus.

Pelvic ultrasound: Used to find the cause of pelvic pain, such as an ectopic pregnancy in women, or to detect tumours or masses.

Breast ultrasound: Used to examine a mass in the breast tissue.

Thyroid ultrasound: Used to see the thyroid and to detect any abnormalities.

Scrotal ultrasound: Used to further investigate Pain in the testicles.

Prostate ultrasound: Used to examine any nodules felt during a physical examination.

Musculoskeletal ultrasound: Used to examine any joint or muscle Pain for conditions, such as a tear.

Intraoperative ultrasound: Used to help the surgeon during a minimally invasive operation or Biopsy.

Interventional ultrasound: Used by an interventional radiologist to guide a minimally invasive procedure.

Intravascular Ultrasound (IVUS): Used to provide direct visualization and measurement of the inside of blood vessels.

Endoscopic ultrasound: Used to obtain direct Ultrasound examination of the inside of a body cavity or organ, using an Ultrasound transducer inside an endoscope (a small, flexible tube with a light and a lens at the end).

How are ultrasounds performed?

An Ultrasound procedure may be done on an outpatient basis, or as part of inpatient care. Although each facility may have specific protocols in place, generally, an Ultrasound procedure follows this process:

  • A gel-like substance will be smeared on the area of the body to undergo the Ultrasound (the gel acts as a conductor).
  • Using a transducer, a tool that sends Ultrasound waves, the Ultrasound will be sent through the patient’s body.
  • The sound from the transducer will be reflected off structures inside the body, and the information from the sound waves will be analyzed by a computer.
  • The computer will create an image of these structures on a television screen. The moving pictures can be recorded.

There are no confirmed adverse biological effects on patients or instrument operators caused by exposures to Ultrasound.