Hydrostatic-pressure-dependent acoustic properties of brain tissue and their implications in non-invasive ICP monitoring.

Abstract

Ultrasound-based non-invasive intracranial pressure (ICP) monitoring is of significance in neurological surgery, but its core limitation lies in the mechanical mechanisms of brain tissue's response to pressure, which have not been fully elucidated. This study aimed to clarify the acoustic responses of brain tissue under changing pressures using a hydrostatic pressure system. The ultrasonic speed and the attenuation coefficient were quantified via the Acoustic Pulse Transmission (APT) method at broad frequencies (0.1-2.0 MHz). Results demonstrated that the ultrasonic speed increased nonlinearly with hydrostatic pressure, rising from 1539 ± 6 m·s^-1 at baseline (0 kPa) to 1548 ± 6 m·s^-1 at 9 kPa, whereas the attenuation coefficient was frequency-dependent but pressure-independent. These findings indicate that the quantified relationship between ultrasonic speed and hydrostatic pressure establishes a biophysical basis for the feasibility of ultrasound-based ICP estimation.