Ultrasonic Characterization of Human Scalp

Objective: The ultrasonic properties of scalp may be relevant to a variety of applications including transcranial ultrasound. However, there is no information about the ultrasonic properties of scalp available in the literature. While ultrasonic studies of skin from other anatomic regions have been previously reported, scalp tissue is gener-ally thicker with a higher density of hair follicles, blood vessels and sebaceous glands. Thus, it is unknown if the ultrasonic properties of scalp are similar to skin from other regions. The goal of this study was to measure the ultrasonic properties of human scalp. Methods: Pulse-echo measurements were performed with a 7.5 MHz ultrasound transducer to determine the speed of sound (SOS), frequency slope of attenuation (FSA) and integrated backscatter coefficient (IBC) of 32 specimens of formalin-fixed human scalp from four donors. Results: The means +/- standard deviations for these three ultrasonic quantities measured in the frequency range 2.83-7.74 MHz over all specimens were SOS = 1525 +/- 16.92 m/s, FSA = 2.59 +/- 0.724 dB/cm/MHz and IBC = 0.122 +/- 0.0746 cm-1 Sr-1. Conclusion: These values are comparable to reported values for human skin from other parts of the body, but some differences in SOS and IBC exist.