Higher frequencies permit less penetration but provide a higher resolution image for which structures?

• A. Large organs (liver)
• B. Brain and spine MRI
• C. Superficial structures (breast tissue)
• D. Gadolinium

Answer: (C)

Higher frequencies in ultrasound give shorter wavelengths, which lets the system resolve smaller details and thus produce higher image resolution. But they’re more readily attenuated by tissue, so they don’t penetrate as deeply. That trade-off makes high-frequency probes ideal for imaging superficial structures, such as breast tissue, where you can maximize detail without needing deep penetration. For deeper organs like the liver, a lower frequency is used to achieve enough penetration, even though the resolution is not as sharp. Brain and spine imaging are typically done with MRI, not ultrasound, and gadolinium is a contrast agent, not a structure being imaged.