Yes it cause the same effect of gases

This is hard to answer without the context, where the term micro bubbles appears.

However, in medical ultrasound imaging, micro-bubbles is related to the intensity of the ultrasound and also the the contrast agent (if any) that was used to cause micro-bubbles. These bubbles are spontaneous, which means they are formed when low pressure (from the ultrasound beam) passes through the medium, and disappear when no ultrasound is applied.

I think there is a distinction between the bowel gas and micro-bubbles in the context that you are referring to. 'Bowel gas' is static (always there once formed) and the other is dynamic (only form when ultrasound is applied)

Hello,

From my understanding there are a few factors:

-Sound passes through tissue due to the speed of sound in soft tissues normally being about 1540m/s when that of gas is around 343m/s (?). The marked difference causes an interface which reflects most of the sound back to or away from the probe.

-Bowel gas is a larger, smoother interface as it is commonly of a large quantity. This makes it more of a 'specular reflector', which will reflect the sound beam back at a perpendicular angle to the probe when scanned at 90 degrees to the interface, or if the interface is non-perpendicular, will reflect the sound in an equal and opposite direction, commonly away form the probe, leading to a loss of information or shadowing beyond the interface as there is no further propagation of the sound wave through tissues

-While microbubbles for Contrast enhanced ultrasound are a gas (Commonly sulphur hexafluoride) and therefor will have a similar difference in speed of sound leading to strong reflective interface, they are about 3-5 μm in size (similar to that of a red blood cell). Due to there smaller size they are actually smaller than the wavelength of the ultrasound beam, which makes them a 'Riley scattering interface'. Meaning that the sound is scattered in all directions, this means that while yes some sound will be reflected away from the probe leading a small loss in image data, some sound will continue to propagate through the tissues and still reflect back to the probe, providing you with some image information beyond that gaseous interface.

- Nhan Minh Le is absolutely correct with stating that some are spontaneous. This is because even in the absence of microbubbles being actively injected for the use of contrast ultrasound the nature of a sound waves peaks and troughs between compression and rarefaction can lead to spontaneous bubble formation in what is known as 'cavitation' this occurs at low frequency scanning. Due to the low pressures associated with the rarefaction stages of the wavelength the low pressure can cause gaseous formation spontaneously within tissues, this can also lead to changes in cell permeability and is often avoided in day to day medical ultrasound and is known as a mechanical effect of ultrasound however, I believe some places try to use if to help break down fat tissues as an alternative to liposuction for fat loss therapies.

Sorry for the long answer, but I hope that some of it might be useful.

Kind Regards,

Stephen Moore

tq u so much sir