Color-coded Doppler Ultrasonography: Treatment, Effects & Risks

In color-coded Doppler ultrasonography, a physician uses an ultrasound machine to examine the vascular structures of the body, taking advantage of the physical Doppler effect of different sound frequencies being emitted by faster- and slower-moving objects. During the examination, a transducer sends a sound into the body that is reflected back by the blood at different frequencies, with the particular sound frequency determined by the distance and speed of movement of the blood. The individual frequencies and velocities are mapped in different colors by a connected computer and in this way help the physician locate vessels and detect circulatory disorders as well as thromboses or malfunctions of the heart.

What is color-coded Doppler ultrasonography?

Color-coded Doppler sonography is an examination of the blood vessels. The practical basis for this procedure is the technique of ultrasound. Color-coded Doppler sonography is an examination of the vessels. The practical basis for this procedure is the technique of ultrasound. The physical principle of the Doppler effect is the theoretical basis of the examination. Physics uses the Doppler effect to describe a change in the frequency of sound waves as soon as they are reflected or dispersed on the basis of a fast-moving object. In the case of a rapidly approaching and receding siren, for example, the bystander hears the sound in frequencies that change with distance. Color-coded Doppler sonography transfers this principle to human blood and sends sound waves into the vessels. Depending on the distance and direction of flow of the blood, the sound waves sent in this way come back in different frequencies. The data obtained in this way is recorded by a computer and coded with different colors. In this way, both the flow direction and the flow velocity of the blood can be displayed using different color markings. In addition, the physician can assess the exact location of blood vessels, arteries and veins in this way and evaluate thromboses or altered vessel walls. Examination of the carotid arteries, assessment of flow conditions from the heart, and assessment of renal blood flow are important uses of color-coded vascular examination.

Function, effect, and goals

Color-coded Doppler ultrasonography is used primarily to diagnose circulatory disorders. The procedure is capable of distinguishing arterial blood flow from venous blood flow. Thus, the examination enables the physician to make statements about the blood circulation as a whole. The procedure can also detect smaller vessels that cannot be visualized using other techniques. In many cases, this form of Doppler sonography is also used to detect and evaluate heart muscle defects and impaired heart valve function. For the patient, the examination is a more or less normal ultrasound examination. Ultrasound gel is applied to the relevant areas in preparation. The transducer of an ultrasound machine is then passed over the areas and sends a sound into the body through the skin during the examination. This sound reaches the flowing blood inside and is reflected back in the form of a reflection. The frequency of the reflected sound depends on the spatial condition and distance of the blood from the transducer. The different tones are recorded by a measuring sensor on the ultrasound device. A computer is connected to the device, which evaluates the transmitted data and codes each of the different frequencies with a different color tone. For example, blood displayed in red corresponds to blood flowing toward the transducer. If, on the other hand, the blood flow moves away from the transducer, the frequency of the reflected sound changes and the computer codes the new sound frequency with blue color. Color-coded Doppler ultrasonography also allows the respective flow velocity of the blood to be displayed. To distinguish between fast and slow flowing blood, the connected PC encodes faster blood movements toward the transducer, therefore, with a brighter red, for example. In the same scheme, blood moving rapidly away from the transducer is represented in a lighter blue. Blood flow moving slowly away from the transducer is coded a darker blue.A blood flow slowly moving towards the head in the conclusion a dark red.

Risks, side effects and dangers

As a noninvasive vascular examination procedure, color-coded Doppler ultrasonography is not associated with any risks, pain, or side effects for the patient and likewise does not require hospitalization. The accuracy in the localization of circulatory disorders is the main distinctive feature of the procedure. The principle of Doppler sonography differs from other potential methods of vascular examination in particular by the relatively precise imaging of the smallest vascular structures. This makes color-coded Doppler sonography superior to conventional examination methods in this field in many respects, and it has since been further developed into many additional procedures. Tissue and power Doppler sonography, for example, are based on the same principle. In the tissue variant, movements of the tissue can be depicted in addition to the blood flow. In addition to the values of the color-coded Doppler, the power Doppler also determines the specific energy of the flowing blood. The significance of the Doppler effect for medicine is thus a revolutionary one, because precise localization is crucial, especially in the case of a circulatory disorder of the myocardium. In such cases of malperfusion of the muscle tissue layer between the outer and inner skin of the heart, for example, color-coded Doppler ultrasonography can provide a framework for potential therapeutic procedures, whereas other methods are unable to do so because of their lack of accuracy.