Ultrasonic properties of brain and scalp

Transcranial ultrasound is used as a tool to evaluate the cerebrovascular function of the brain, to open the blood–brain barrier for targeted drug-delivery and to improve brain function with conditions such as epilepsy and other pathologies. Because the ultrasound must pass through the scalp and skull before reaching the brain, knowledge of the ultrasonic properties of these tissues is important. Prior to our work, no studies of the ultrasonic properties of human scalp were to be found in the literature and only aggregate values of ultrasonic properties were reported for mammalian brain, a highly inhomogeneous organ. The goal of the work that will be presented here was to ultrasonically characterize the speed of sound, frequency slope of attenuation and integrated backscatter coefficient of human scalp and the spatial variation of these properties in mammalian brain.