Ultrasound imaging or sonography produces images of the inside of the body using high-frequency sound waves. These are real time images that show the structure and functioning of the organs. Depending on the goals of a particular test, the phenomena being invested and equipment available, the ultrasound image to be used can be of four different types- 2D, 3D, 4D and Doppler ultrasound.
The Doppler Effect is applied in sonography to provide imaging of blood vessels and flow within them. Reflected sound waves are used in a Doppler ultrasound to see how blood flows through a blood vessel. It helps doctors evaluate blood flow through major arteries and veins such as those of arms, legs and neck. It can show the blocked or reduced blood flow in the major arteries of the neck that could cause a stroke. It can also help in diagnosing deep vein thrombosis (blood clots in leg veins) which can cause pulmonary embolism (blocked blood flow to the lungs). Doppler ultrasound is also used to check the health of the fetus by looking at the blood flow in an unborn baby.
Process: During Doppler ultrasound, gel is applied on the targeted area of the body to allow the sound waves to pass through. A hand-held instrument, also known as transducer, is then passed lightly over the skin above the blood vessel. The instrument sends and receives sound waves that are amplified through a microphone. The movement of blood cells causes a change in pitch of the reflected sound waves which is known as the Doppler Effect. The information is processed by the computer to provide graphs or pictures representing the flow of blood.
The three basic types of Doppler ultrasound are:
“Bedside” or Continuous Wave Doppler: Change in pitch of the sound waves is used to evaluate the blood flow through the area that may be blocked or narrowed. It provides a quick estimate of the extent of blood vessel damage or disease.
Duplex Doppler: Standard ultrasound methods are used to produce a picture of a blood vessel and the surrounding organs. The Doppler sounds are converted into a graph to get information about the speed and direction of blood flow through the blood vessel.
Color Doppler: The Doppler sounds are converted into colors that are overlaid on the image of the blood vessel and that represent the speed and direction of blood vessel through the vessel. Power Doppler is a special type of color Doppler which is used to get some hard and impossible images.
The use of Doppler machines is a boon to the medical science. Many used doppler ultrasound for sale are available. There are a number of online shops that deal in ultrasound instruments and also provide demo ultrasound scanners for the ease of customers. They provide these devices at reasonable prices.