Ultrasound imaging, also known as “ultrasound scanning” or “sonography” includes exposure of body parts to sound waves of high frequency in order to obtain images of the inside of the body. During the ultrasound examination, there is no ionizing radiation (like the one used in X-rays) which means that they are not harmful for the human body. Considering the fact that ultrasound imaging is conducted in the real time (so called technique of live imaging), images can show structure and movement of the organs inside the body, as well as the blood flow through the veins.
Ultrasound imaging is a non-invasive medical examination which helps doctors in diagnosing and treatment of medical conditions.
Conventional ultrasound shows images in thin, flat body parts. Progress in ultrasound technology includes three-dimensional (3D) ultrasound which converts the information about sound waves into 3D images. Four-dimensional (4D) ultrasound is a 3D ultrasound in motion.
Doppler ultrasound examination can also be a part of ultrasound examination. Doppler ultrasound is a special ultrasound technique which enables display of the blood flow through the vein, including large arteries in the body and veins in the abdomen, arms, legs, neck, as well as the blood flow inside of certain organs.
There are three types of Doppler ultrasound:
- Color Doppler is a technique where the computer is used to convert Doppler measurements into the color spectrum because of the speed and direction visualisation of blood flow through the vein.
- Power Doppler is a newer technique that is more sensitive than color Doppler and it enables a more detailed display of blood flow, especially when the blood flow is weak or minimal. However, Power Doppler does not help radiologist to determine the direction of the blood flow, which in same cases can be very important.
- Spectral Doppler instead of visual display of Doppler measurements, displays the blood flow graphically, in terms of distance travelled in a unit of time.