What typically appears hyperechoic on ultrasound imaging?

In the context of ultrasound imaging, hyperechoic structures are those that produce a greater echogenic signal compared to surrounding tissues, resulting in brighter areas on the image. Bone and gas are typically associated with hyperechoic appearances.

Bone is densely packed and does not allow ultrasound waves to penetrate well, which leads to strong reflections of the sound waves, making it appear very bright or hyperechoic. Gas, on the other hand, reflects ultrasound waves significantly due to its low density and differences in acoustic impedance compared to soft tissues, also causing it to appear hyperechoic.

When considering the other options, the renal medulla and the gas would not generally show consistent hyperechoic features, as the renal medulla can appear hypoechoic compared to the renal cortex. The spleen and lung can also demonstrate varying echogenicity but are not predominantly hyperechoic. Lastly, the liver and spleen are typically seen as hypoechoic relative to other surrounding structures, particularly the brighter echogenicity of tissues like fat or fibrous structures.

Therefore, the choice identifying bone and gas as hyperechoic aligns with the understanding of ultrasound imaging, making it the appropriate answer.