University of Oulu

Zhao, Z.; Myllylä, T. Recent Technical Progression in Photoacoustic Imaging—Towards Using Contrast Agents and Multimodal Techniques. Appl. Sci. 2021, 11, 9804.

Recent technical progression in photoacoustic imaging : towards using contrast agents and multimodal techniques

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Author: Zhao, Zuomin1; Myllylä, Teemu1,2
Organizations: 1Optoelectronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, 90014 Oulu, Finland
2Research Unit of Medical Imaging, Physics and Technology, Faculty of Information Technology and Electrical Engineering, University of Oulu, 90220 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.7 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2021
Publish Date: 2022-02-08


For combining optical and ultrasonic imaging methodologies, photoacoustic imaging (PAI) is the most important and successful hybrid technique, which has greatly contributed to biomedical research and applications. Its theoretical background is based on the photoacoustic effect, whereby a modulated or pulsed light is emitted into tissue, which selectively absorbs the optical energy of the light at optical wavelengths. This energy produces a fast thermal expansion in the illuminated tissue, generating pressure waves (or photoacoustic waves) that can be detected by ultrasonic transducers. Research has shown that optical absorption spectroscopy offers high optical sensitivity and contrast for ingredient determination, for example, while ultrasound has demonstrated good spatial resolution in biomedical imaging. Photoacoustic imaging combines these advantages, i.e., high contrast through optical absorption and high spatial resolution due to the low scattering of ultrasound in tissue. In this review, we focus on advances made in PAI in the last five years and present categories and key devices used in PAI techniques. In particular, we highlight the continuously increasing imaging depth achieved by PAI, particularly when using exogenous reagents. Finally, we discuss the potential of combining PAI with other imaging techniques.

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Series: Applied sciences
ISSN: 2076-3417
ISSN-E: 2076-3417
ISSN-L: 2076-3417
Volume: 11
Issue: 21
Article number: 9804
DOI: 10.3390/app11219804
Type of Publication: A2 Review article in a scientific journal
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
217 Medical engineering
Funding: This research was funded in part by the Academy of Finland, grant number 318347.
Academy of Finland Grant Number: 318347
Detailed Information: 318347 (Academy of Finland Funding decision)
Copyright information: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (