Relationship between skull phantoms physical characteristics and acoustic wave signal features

Abstract

During medical investigations of the head, ultrasound measurements can offer information with simple, non-invasive, and real-time procedure. However, for human adult applications, the clinical treatment of transcranial acoustic imaging remains a challenge by the presence of the skull, results in acoustic aberrations caused by two main phenomena, i.e., attenuation and distortion. These aberrations may affect the signal understanding because of the induced artifacts and the inaccuracy of the imaging target structural information. Variations of the physical properties of the skull, its thickness and porosity, will strongly affect the mechanical properties of the medium and thus the acoustic response. We propose a method to understand the influence of these characteristics on the signal degradation. In order to mimic the human adult skull, a large quantity of epoxy resin-based phantoms is created to explore all the possible physical characteristic variation in the bone. Additional components, titanium dioxide and seeds, will be added to the samples to recreate the acoustic scattering effects of a skull bone. Signal features from pulse-echo mode ultrasound, such as signal attenuation or broadening, will be extracted and studied in the time and frequency domain. In this paper, we are looking for relationship between these physical parameters and the signal features, with the objective to determine bone characteristics without any direct access in later experiments; and going a step further into aberration correction during transcranial imaging procedure.

Photoacoustic imaging for detection of blood clot with different sizes in the brain

“…PAI has demonstrated its capability for measuring the blood flow, hemoglobin concentration, and oxygen saturation in biological tissue for the purposes of diagnosis of diseases and treatment monitoring of varieties of disorders in animals and humans [7][8][9][10][11][12][13]. However, the skull bone represents a highly acoustical impedance mismatch and dispersive barrier for the propagation of acoustic waves [14][15][16][17]. In addition, the optical illumination efficiency is affected by the skull due to important absorption and scattering [18].…”