What is the correct order of attenuation from lowest to highest?

The correct order of attenuation from lowest to highest is aligned with the inherent properties of different tissues in their interactions with ultrasound waves. Water and biological fluids have low attenuation because they do not significantly scatter or absorb ultrasound; thus, they transmit sound waves efficiently. Fat, while having slightly higher attenuation than fluids, still allows for considerable transmission of ultrasound signals compared to denser tissues.

As we progress to soft tissue, the attenuation increases further due to the density and structure of the tissue. Muscle has even higher attenuation compared to soft tissue because of its denser cellular makeup. Bone and lung represent the highest levels of attenuation; bone, being a very dense material, absorbs and scatters ultrasound waves significantly more than softer tissues. Air, which contains pockets of gas, presents the highest level of attenuation because it dramatically impedes the passage of sound waves, causing almost complete reflection and minimal transmission.

This understanding of how various media attenuate ultrasound waves is essential in clinical practice to optimize imaging and understand the limitations of ultrasound in different anatomical regions.