List two imaging advantages of tissue harmonic imaging compared to fundamental frequency imaging.

• A. Reduced near-field clutter and improved lateral resolution
• B. Increased near-field clutter and worse lateral resolution
• C. No change in resolution but faster imaging
• D. Improved depth penetration with heavier energy

Answer: (A)

Two imaging advantages come from using the tissue-generated second harmonic signal instead of the transmitted fundamental frequency. The harmonic signal is produced mainly inside the tissue and is filtered to reject the fundamental, so clutter from near-field reflections and superficial interfaces is greatly reduced. At the same time, the harmonic frequency is higher, giving a shorter wavelength and a narrower beam, which sharpens the lateral resolution. So the best answer reflects reduced near-field clutter and improved lateral resolution. The other options don’t fit because harmonic imaging does not increase near-field clutter, does not rely on faster imaging or unchanged resolution, and it does not improve depth penetration (in fact, higher frequency signals attenuate more, often limiting penetration).