For the most part, images must be created from second harmonics. For example, when the fundamental frequency is 2 MHz, this frequency is filtered out. Therefore, the image is only formed by the first harmonic at 4 MHz. Due to this arrangement, artifactual echoes from the abdominal wall reverberations are excluded. In addition, NTHI eliminates half the artifacts seen in conventional ultrasound.
Artifacts typically occur when sound waves penetrate and exit the body wall.
However, the sound generated in NTHI exits the body wall only, generating half the artifacts seen in conventional ultrasonography. Initially, NTHI was seen to be particularly useful in scanning larger patients. Thick abdominal walls produce more reverberation artifacts. Therefore, NTHI should be used as the default in all patient cases. Ultimately, NTHI improves diagnostic confidence.