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Unlike arterial ultrasonography, venous ultrasonography is carried out with the probe in a transversal position, (perpendicular to the vein axis), displaying cross-sections of the veins. [4] All collateral veins are better detected this way, including perforator veins, but of most importance is the detection of venous thrombosis.
Doppler measurements which trace the echoes of the generated soundwaves received by the probe, enable the direction and velocity of the blood flow to be depicted. The overlay of color onto the Doppler information lets these images be seen more clearly. [8] The choice of a probe will depend on the depth needed to be studied.
Ultrasonography of chronic venous insufficiency of the legs; Duplex evaluation is usually done prior to any invasive testing or surgical procedure. [8] Ultrasound duplex scanning can provide additional information that may guide therapeutic decisions. The location and severity of arterial narrowings and occlusions can be identified.
Ultrasound methods including duplex and color flow Doppler can be used to further characterize the clot [117] and Doppler ultrasound is especially helpful in the non-compressible iliac veins. [119] CT scan venography, MRI venography, or a non-contrast MRI are also diagnostic possibilities. [120]
A duplex ultrasound (doppler ultrasonography and b-mode) can detect venous obstruction or valvular incompetence as the cause, and is used for planning venous ablation procedures, but it is not necessary in suspected venous insufficiency where surgical intervention is not indicated. [10] [6]
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
On duplex ultrasound, demonstration of echogenic material within the portal vein, complete or partial absence of colour flow in the portal vein, presence of collateral vessels around the portal vein or gall bladder that bypass the portal vein. [9] Portal vein thrombosis grading after Yerdel et al
Lower limb venography is indicated in deep vein thrombosis, oedema with unknown cause, and congenital abnormality of the venous system. Less frequently it is used to demonstrate the incompetent valves of perforating veins. Doppler ultrasound is preferable rather than venography to access the competence of the veins.