<Li> Measured areal density in g cm </Li> <Li> Z - score, the number of standard deviations above or below the mean for the patient's age, sex and ethnicity </Li> <Li> T - score, the number of standard deviations above or below the mean for a healthy 30 - year - old adult of the same sex and ethnicity as the patient </Li> <P> While there are many different types of BMD tests, all are non-invasive . Most tests differ according to which bones are measured to determine the BMD result . </P>

What is a t score in bone density
find me the text answering this question