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Intravascular ultrasound image of a coronary artery (left), with color-coding on the right, delineating the lumen (yellow), external elastic membrane (blue) and the atherosclerotic plaque burden (green). The percentage stenosis is defined as the area of the lumen (yellow) divided by the area of the external elastic membrane (blue) times 100.
For example, the superficial venous system (SVS) can be very well examined using a high-frequency probe of 12 MHz. For patients who have thick adipose tissue, a probe of 7.5 MHz will be required. Deep veins require probes of around 6 MHz, while the abdominal vessels are better studied with probes of between 4 and 6 MHz. [9]
A lower limbs venous ultrasonography may refer to: Ultrasonography of chronic insufficiency of the legs; Ultrasonography of deep venous thrombosis
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.
The third lumen is useful for administration of fluids, antibiotics, medicines, or contrast without having to find other places for intravenous access. This type of catheter is useful for initiating venous access for acute renal failure patients quickly for dialysis before a permanent catheter is inserted for long term access. [1]
SWI Image acquired at 4 Tesla showing the veins in the brain. Susceptibility weighted imaging (SWI), originally called BOLD venographic imaging, is an MRI sequence that is exquisitely sensitive to venous blood, hemorrhage and iron storage. SWI uses a fully flow compensated, long echo, gradient recalled echo (GRE) pulse sequence to
The venous valves serve to prevent regurgitation (backflow) due to the low pressure of veins, and the pull of gravity. [1] They also serve to prevent the over-widening of the vein. [20] [21] A venous valve is bicuspid (having two leaflets) and is formed by an infolding of part of the tunica intima on either side of the lumen of the veins.
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers.