Sometime in the past few million years, collapse at the top of the cave and surface erosion created the natural entrance of Carlsbad Cavern. This opened previously hidden underground cave passageways to the world above for the first time.
The Society of Diagnostic Medical Sonography (SDMS) defines sonography as diagnostic medical procedure that uses high frequency sound waves (ultrasound) to produce dynamic visual images of organs, tissues, or blood flow inside the body. This type of procedure is often referred to as a sonogram or ultrasound scan.
A carotid ultrasound is a noninvasive, painless screening test. Your doctor uses an ultrasound to look at the carotid arteries in your neck and see the flow of blood through them. Ultrasound, also called sonography, uses sound waves instead of X-rays to make images. carotid ultrasound is an important test that can detect narrowing, or stenosis of the carotid arteries. Carotid artery stenosis is a major risk factor for stroke.