Photoacoustic Imaging Techniques in Biomedical Applications

Photoacoustic imaging merges the high contrast of optical absorption with the deep penetration of ultrasound detection to produce images of biological tissues with rich structural, functional and molecular information. By illuminating tissue with pulsed laser light, endogenous chromophores such as haemoglobin or exogenous agents absorb energy and generate ultrasound waves via thermoelastic expansion. These waves are captured by ultrasonic sensors and reconstructed into two- or three-dimensional images. Variants include photoacoustic tomography for deep-tissue imaging and photoacoustic microscopy for high-resolution surface studies. Recent innovations in all-optical sensors, parallelised detector arrays and compressed sensing have dramatically improved acquisition speed and image fidelity. Together, these advances underpin a growing range of preclinical and clinical applications, from mapping microvascular networks and monitoring tumour oxygenation to guiding minimally invasive interventions.

Research from Nature Portfolio

Recent studies have demonstrated an all-optical photoacoustic tomography scanner capable of volumetric vascular imaging in only a few seconds by parallelising the sensor readout, increasing laser pulse-repetition rates and applying compressed sensing. This rapid approach produces dynamic three-dimensional visualisations of arterioles, venules and tissue perfusion to depths approaching 15 mm, minimising motion artefacts and enabling quantitative assessment of peripheral vascular disease, skin inflammation and rheumatoid arthritis. Separately, a single-breath-hold photoacoustic computed tomography system has been developed for breast imaging, delivering 255 µm in-plane resolution at a 10 Hz frame rate over a 4 cm penetration depth. By acquiring a full volumetric scan within 15 s, this modality reveals tumour-associated increases in vessel density and compliance differences without ionising radiation or exogenous contrast agents, showing promise for high-sensitivity detection in dense breasts.

Photoacoustic Imaging Techniques in Biomedical Applications publication trend

The graph below shows the total number of articles in photoacoustic imaging techniques in biomedical applications across all publications each year (not limited to Nature Index journals).

Technical terms

Photoacoustic imaging (PAI): A hybrid modality that uses pulsed optical excitation to generate ultrasound waves in absorbing structures and reconstructs these signals into images of tissue composition and function.

Photoacoustic tomography (PAT): A deep-tissue imaging technique that acquires ultrasound signals from multiple angles to reconstruct cross-sectional or volumetric maps of optical absorption.

Photoacoustic microscopy (PAM): A high-resolution imaging approach that employs focused optical excitation and raster scanning to visualise microvascular and cellular features at shallow depths.

Fabry–Pérot ultrasound sensor: An optical cavity device in which pressure-induced changes in film thickness modulate reflected light, allowing sensitive detection of ultrasonic waves.

Compressed sensing: A signal-processing strategy that reconstructs images from undersampled data by exploiting sparsity, reducing acquisition time without sacrificing resolution.

Limited-view artefacts: Reconstruction distortions that arise when acoustic detectors do not fully enclose the target, leading to incomplete sampling of emitted waves.

Endogenous contrast: Optical absorption by intrinsic tissue constituents such as haemoglobin, melanin or lipids that generates photoacoustic signals without added agents.

Exogenous contrast: Externally introduced dyes, nanoparticles or molecular probes that enhance optical absorption at specific wavelengths for targeted imaging.

References

1. A fast all-optical 3D photoacoustic scanner for clinical vascular imaging. Nature Biomedical Engineering (2024).
2. Single-breath-hold photoacoustic computed tomography of the breast. Nature Communications (2018).
3. A review of clinical photoacoustic imaging: Current and future trends. Photoacoustics (2019).
4. Review on practical photoacoustic microscopy. Photoacoustics (2019).
5. Tutorial on photoacoustic tomography. Journal of Biomedical Optics (2016).
6. Model-Based Learning for Accelerated, Limited-View 3-D Photoacoustic Tomography. IEEE Transactions on Medical Imaging (2018).