This disclosure relates to systems and methods for measuring the composition of a body part of a patient, or for otherwise determining a clinically relevant fact using characteristics of tissue in or proximal to said body part. In an example, this disclosure relates to measuring the electrical impedance of an organ or portion of an organ, such as the female breast, so as to obtain clinically relevant information. In an aspect, the system and method can be used for measuring and utilizing certain information such as breast density data and other risk factors for determination or classification of a womans likelihood to develop breast cancer. Other aspects quantify or qualify a womans responsiveness to a drug or hormonal therapy.