Sonography is a diagnostic imaging technique based on the application of ultrasound. It is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs. Its aim is often to find a source of a disease or to exclude pathology. The practice of examining pregnant women using ultrasound is called obstetric ultrasound and was an early development and application of clinical ultrasonography.
Ultrasound refers to sound waves with frequencies which are higher than those audible to humans. Ultrasonic images, also known as sonograms, are made by sending pulses of ultrasound into tissue using a probe. The ultrasound pulses echo off tissues with different reflection properties and are recorded and displayed as an image.
3D Sonography is a medical ultrasound technique, often used in fatal, cardiac, trans-rectal and intra-vascular applications. 3D Sonography refers specifically to the volume rendering of ultrasound data and is also referred to as 4D (3-spatial dimensions plus 1-time dimension) when it involves a series of 3D volumes collected over time.