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.
How Long Does Puberty Last For Boys. When there is an increase in the size of the testicles, it is the first sign of puberty for boys. In the puberty early stage, you can see light hair growth on the genitals and under the arms. A boy starts to gain height and have facial hair during this time period.