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.
Growth in teenage boys occurs in spurts, generally over four to five years. The first growth spurt may start anytime between ages 10 and 14. Outside that age range, puberty is either delayed or premature. The following changes occur in a boyâs physical development. An increase in height usually begins at age 12 or 13 and continues until age 17 or 18. (If some visible growth has not occurred by age 15, consult your doctor.) Body hair appears, usually beginning in the pubic area at ages 11 to 12.