Also, Doppler can detect abnormal blood flow within the heart, which can indicate a problem with one or more of the heart's four valves. Color Doppler. Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow.
Quick Answer. The age at which people grow armpit hair varies, but for boys it is often between the ages of nine and 14. Girls typically begin to grow this hair between eight and 13 years of age. Keep Learning.
Several areas of the body begin to change, including: 1  Muscles: Boys start developing more muscle during puberty. 2  Shoulders: Boysâ shoulders become broader during puberty as well. 3  Height: Boys grow in height quickly during puberty, often in response to growth spurts. 4  Acne: Many boys develop acne during puberty.