Low frequency detection in clinical multispectral optoacoustic tomography

Area of Science:

• Optoacoustic imaging
• Biomedical engineering
• Signal processing

Background:

• Optoacoustic (photoacoustic) detectors capture broadband signals crucial for determining absorber size.
• Characterizing the sub-1 megahertz response is vital for imaging larger structures (centimeter-sized organs).
• Current methods struggle to reliably measure kilohertz frequency responses, limiting understanding of large-scale imaging.

Purpose of the Study:

• To develop an experimental setup for determining the lowest measurable frequency of optoacoustic detectors.
• To investigate the impact of low-frequency responses on optoacoustic image reconstruction and fidelity.
• To address the limitations in characterizing the sub-1 megahertz frequency range.

Main Methods:

• Developed a novel experimental arrangement to measure the lowest detectable frequencies.
• Utilized a standard optoacoustic detector with a 3.4 MHz center frequency and 72% 3-dB bandwidth.
• Simulated and analyzed image reconstruction artifacts caused by inaccurate kilohertz frequency response data.

Main Results:

• Demonstrated that a common optoacoustic detector can capture signals down to 75 kilohertz.
• Identified significant artifacts in image reconstruction when using erroneous kilohertz frequency response data.
• Quantified the detector's ability to capture low spatial frequencies relevant for organ imaging.

Conclusions:

• Optoacoustic detectors possess a greater low-frequency detection capability than previously characterized.
• Accurate characterization of kilohertz frequencies is essential for reliable optoacoustic image reconstruction.
• Incorporating low-frequency information enhances the fidelity of optoacoustic images, particularly for larger structures.