Acoustic Enhancement And Shadowing

What is acoustic enhancement?

Clear liquids allow ultrasound to past directly through without much alteration so that echoes that come from tissue behind liquid are usually enhanced. This is known as "acoustic enhancement".

How to to displace gas-field bowel?

Drinking enough water to fill the stomach will displace the gas-bowel, providing an acoustic window. This is particularly useful in visualising the body and tail of the pancreas.

Gas in the oval or elsewhere can present a variety of sonographic patterns. The beam can be scattered, reflected, observed, and refracted, making it very difficult to image underlying structures. For this reason, ultrasound cannot be used to image the normal lungs or to demonstrate lungs disease other than peripheral masses. Chest X-ray provide much better information.

Dense material such as bones or calculi (stones) cast shadows or structures behind them, because the ultrasound waves do not go through them. This is known as "acoustic shadowing". 

e.g., ribs may obstruct the field of view so the structures behind must be examined obliquely through the intercostal spaces.

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