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Speed of Sound and Attenuation Temperature Dependence of Bovine Brain: Ex Vivo Study
Author(s) -
Dahis Daniel,
Azhari Haim
Publication year - 2020
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.1002/jum.15203
Subject(s) - attenuation , medicine , ultrasound , ex vivo , white matter , biomedical engineering , thermocouple , speed of sound , attenuation coefficient , focused ultrasound , brain tissue , magnetic resonance imaging , nuclear magnetic resonance , nuclear medicine , in vivo , acoustics , radiology , materials science , optics , physics , microbiology and biotechnology , biology , composite material
Objectives Brain treatments using focused ultrasound (FUS) offer a new range of noninvasive transcranial therapies. The acoustic energy deposition during these procedures may induce a temperature elevation in the tissue; therefore, noninvasive thermal monitoring is essential. Magnetic resonance imaging is the current adopted monitoring modality, but its high operational costs and limited availability may hinder the accessibility to FUS treatments. Aiming at the development of a thermometric ultrasound (US) method for the brain, the specific objective of this investigation was to study the acoustic thermal response of the speed of sound (SOS) and attenuation coefficient (AC) of different brain tissues: namely white matter (WM) and cortical matter. Methods Sixteen ex vivo bovine brain samples were investigated. These included 7 WM and 9 cortical matter samples. The samples were gradually heated to about 45°C and then repeatedly scanned while cooling using a computerized US system in the through‐transmission mode. The temperature was simultaneously registered with thermocouples. From the scans, the normalized SOS and AC for both tissues were calculated. Results The results demonstrated a characteristic cooldown temporal behavior for the normalized AC and SOS curves, which were related to the temperature. The SOS curves enabled clear differentiation between the tissue types but depicted more scattered trajectories for the WM tissue. As for the AC curves, the WM depicted a linear behavior in relation to the temperature. However, both tissue types had rather similar temperature patterns. Conclusions These findings may contribute to the development of a US temperature‐monitoring method during FUS procedures.