In ultrasound physics, if a 7 MHz transducer is replaced with a 3 MHz transducer for imaging a deep structure, which of the following BEST describes the change?

• A Both spatial resolution and penetration depth improve
• B Spatial resolution decreases and penetration depth increases ✓
• C Spatial resolution increases and penetration depth decreases
• D Both spatial resolution and penetration depth decrease

Explanation

Higher frequency ultrasound provides better spatial resolution (shorter wavelength) but attenuates more rapidly in tissue, limiting penetration. Lower frequency (3 MHz) penetrates deeper but with poorer resolution. This is the fundamental trade-off in transducer selection. The 7 MHz probe sacrifices penetration for resolution; the 3 MHz does the opposite.

Reference: Bushberg, The Essential Physics of Medical Imaging, 3rd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.