Color Doppler | CLINICAL CENTRE

Doppler ultrasound can provide information on the structure of vessels (arteries and veins), as well as the blood circulation in the organs.  This examination can evaluate the arteries and veins in the upper and lower extremities, those in the neck (for example the carotid arteries and the vertebral arteries - these are the arteries supplying the brain), and in the abdomen (the vessels related to the kidneys, the liver and the spleen, and the abdominal aorta).  It can also detect if there is narrowing or blockage in a segment of the vessel.  In certain conditions or tumors the blood supply of the affected tissues may change, which may be characteristic of the change itself and can also provide the surgeon with useful information when surgical interventions are needed.  The examination can trace the largest cervical and peripheral arteries, the width of their wall, as well as the size and composition of the plaques on their inner surface.   Furthermore, it can measure flow velocity in a particular segment of the vessel. Flow velocity can be indicative of the degree of narrowing. The examination measures flow velocity based on the Doppler effect, in the vessel segments identified with the help of the ultrasound device.   The probe of the ultrasound device emits high-frequency sound waves (ultrasounds) having a frequency range above that of human hearing range. Part of these sound waves is reflected from certain surfaces in a scattered form, while the other part is absorbed. The reflected waves - like in the case of sonars - are received and collected by the probe, which turns them into electrical signals that the computer uses to create an image on the monitor. Most devices used today are suitable for the examination of several body regions; however, the different examinations may require probes of different size, shape or frequency. It is also suitable for the examination of vessels in the neck, abdominal organs or extremities. The patient needs to remove all clothing from his/her neck, or any other region being examined and should lie face-up on the exam table.   The radiologist will apply a special gel to the skin to enhance passing of ultrasound waves into the body. The transducer is placed on the skin and may also be pressed lightly against it. The physician will move the transducer back and forth to get an image of the different segments of the vessels. Where there is a narrowing, a special ultrasound device is used to measure flow velocity.  No preparation is needed. The measured degree of narrowing indicates probability expressed in percentages.  If the degree of narrowing is so severe that it points to the need for vascular surgery, angiography will also be performed. The procedure has no known harmful effects and can be repeated as many times as needed. The examination should not be painful.