Ultrasound Science

Ultrasound Basics

If you have ever heard an echo you have experienced the fundamentals of ultrasound measurement. You hear an echo when sound travels through air and reflects from a wall or mountain and comes back to your ear. If you time how long it takes for you to hear the echo you can calculate how far away the reflecting object is. The BodyMetrix System generates an ultrasound signal that travels through tissue and then records the reflected signal. Continuing the echo analogy, the BodyMetrix device plays the role of your mouth and your ear. Ultrasound waves travel in tissue and strong reflections occur at the boundary of different tissue types, for example, fat-muscle and muscle-bone.

The illustration shows how the BodyMetrix transmits and receives pulse echos to produce a graph. The signal shows peaks (echos) from each interface (e.g. fat-muscle, muscle-muscle, and muscle-bone)

Body Composition

Body composition is calculated by measuring subcutaneous fat thickness at multiple sites. The number of sites depend on the formula and can range from an approximate single bicep measurement to as many as 9 sites which provide an accurate measurement of body composition. The sites are illustrated below.

Measurement Sites

Most common measurement sites.


Beyond point measurements the BodyMetrix can be used to scan anatomical sites to directly see fat and muscle layers as can be see below in a thigh scan. Scans offer an excellent way to directly monitor the benefits of diet and exercise.

Scan sites

Most common scan sites.