Dual-frequency ultrasound imaging and therapeutic bilaminar array using frequency selective isolation layer

Area of Science:

• Biomedical Engineering
• Ultrasound Technology
• Medical Imaging

Background:

• Transcranial sonothrombolysis requires distinct ultrasound frequencies for therapy (0.5 MHz) and Doppler imaging (2 MHz).
• Existing methods face challenges due to the limited acoustic window for transcranial ultrasound, necessitating a single aperture for both functions.

Purpose of the Study:

• To develop a dual-frequency ultrasound array transducer for integrated diagnosis and therapy in transcranial sonothrombolysis.
• To achieve efficient transmission of both therapeutic and diagnostic ultrasound frequencies through a single aperture.

Main Methods:

• Proposed a bilaminar array design with separate imaging and therapy arrays and a frequency-selective isolation layer.
• Utilized 1-D and 2-D numerical simulations to optimize the isolation layer's acoustic impedance and thickness.
• Fabricated a prototype array transducer based on simulation-derived optimal parameters.

Main Results:

• The frequency-selective isolation layer effectively isolated the 2 MHz imaging array from the 0.5 MHz therapy array.
• Optimized isolation layer parameters: acoustic impedance of 3–4 MRayI and thickness of λ/10.
• The prototype transducer achieved spatial resolutions comparable to conventional imaging transducers.

Conclusions:

• The developed dual-frequency array transducer successfully integrates diagnostic and therapeutic ultrasound capabilities for transcranial sonothrombolysis.
• This technology offers a promising solution for efficient ultrasound delivery through a single aperture, potentially enhancing treatment efficacy.