What is the principle behind harmonic imaging?

• A. Using lower frequencies for clearer images
• B. Using harmonic frequencies to improve image quality by reducing noise and artifacts
• C. Increasing the contrast resolution of images
• D. Utilizing Doppler effects to determine blood flow

Answer: (B)

Harmonic imaging operates on the principle of utilizing harmonic frequencies, which are integer multiples of the fundamental frequency used in ultrasound. This technique improves image quality primarily by reducing noise and artifacts. During the process of ultrasound transmission, the standard frequency sound waves can create various unwanted echoes that clutter the image. However, harmonic imaging leverages the harmonics, often generated as the sound waves interact with tissue, resulting in clearer images with enhanced detail.

The harmonics tend to have better resolution and contrast compared to the fundamental frequencies, allowing for better differentiation between structures and ultimately leading to improved diagnostic capabilities. This reduction of noise and artifacts is a critical feature of harmonic imaging, making it a valuable tool in diagnostic medical sonography.