Quantitative photoacoustic imaging: correcting for heterogeneous light fluence distributions using diffuse optical...

Area of Science:

• Biomedical Optics
• Photoacoustic Imaging
• Diffuse Optical Tomography

Background:

• Photoacoustic (PA) imaging specificity relies on accurate absorption spectroscopy.
• PA signal strength depends on optical absorption and light fluence.
• Accurate optical fluence estimation is crucial for quantitative PA measurements.

Purpose of the Study:

• To demonstrate fluence-related artifacts in PA imaging using a tissue phantom.
• To develop and validate a method combining DOT and PA imaging for fluence correction.
• To improve the quantitative accuracy of PA spectroscopic analysis.

Main Methods:

• A tissue-mimicking phantom was used for proof-of-concept experiments.
• Diffuse optical tomography (DOT) reconstructed spatial distributions of absorption and scattering coefficients.
• DOT-derived fluence maps were used to correct PA images.

Main Results:

• Fluence-related artifacts can lead to misrepresentation of tissue properties in PA images.
• The combined DOT-PA method reduced errors in estimated absorption coefficients from 33% to 6%.
• The derived fluence map primarily contained low spatial frequency components.

Conclusions:

• Combining DOT with PA imaging significantly reduces fluence-related errors.
• This approach enables quantitatively accurate, high-resolution PA imaging of optical absorption coefficients.
• The method offers a pathway to more reliable molecular and functional PA imaging.