| UltraSound - Technology Information Portal||Wednesday, 1 March 2017 |
Phospholipids are a major component of all biological membranes. When placed in water, phospholipids form a bilayer, where the hydrophobic tails line up against each other. This forms a membrane with hydrophilic heads on both sides. This membrane is partially permeable and very flexible.|
Phospholipid containing microbubbles are in use as diagnostic ultrasound contrast agents. Phospholipids can be targeted to atheroma and other pathologic components to enhance atherosclerosis imaging. The majority of these echogenic liposomes range in diameter from 0.25 to 5.0 µm.
• View the DATABASE results for 'Phospholipid' (8).
|Bolus Injection|| |
A bolus is a rapid infusion of high dose contrast agent. Dynamic and accumulation phase imaging can be performed after bolus injection. Since the transit time of the bolus is only a short time, images with high frame rate show the wash in and wash out of the contrast material.
The injection rate and the total injected volume modifż the bolus peak profile. Substantial changes in the concentrations during signal acquisition induce artifacts. Furthermore, the hemodynamic parameters (cardiac output, blood pressure) influence the bolus profile. However, the characteristics of ultrasound contrast agents are favorable with a continuous perfusion.|
See also Negative Bolus.
• View the DATABASE results for 'Bolus Injection' (4).
|Bubble Destruction|| |
• View the DATABASE results for 'Bubble Destruction' (8).
|Negative Bolus|| |
A negative bolus is created after microbubble destruction at a specific location by the absence of bubbles.
• View the DATABASE results for 'Negative Bolus' (3).
|Bubble Rupture|| |
Ultrasound at the microbubble resonance frequency can cause bubble rupture at high acoustic power (mechanical index (MI) greater than 0.5). The result is a transient high-amplitude, broadband signal containing all frequencies, not only the harmonics. It will create a strong signal in B-mode or a short-lasting multicolored, mosaic-like effect in color Doppler sonography.|
Several terms for this typical signal have been used, e.g. induced or stimulated acoustic emission, loss of correlation imaging and sono-scintigraphy.
• View the DATABASE results for 'Bubble Rupture' (5).
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