Highlights

In brief

By pulsing laser light onto human skin and detecting acoustic waves produced, ms-RSOM could non-invasively detect disruptions in blood microcirculation two milimetres below the skin's surface.

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A non-invasive diagnostic test that “listens” to the skin

23 Aug 2022

A*STAR scientists develop an optoacoustic imaging technology for diagnosing disease by assessing subtle blood flow changes in the skin.

Believed to have been coined by William Shakespeare, the phrase “in the pink of health” refers to the rosy glow of the cheeks—commonly perceived as a mark of a healthy disposition. Interestingly, today’s science backs up this age-old notion: functional changes to the tiny blood vessels just beneath the surface of the skin have been linked to serious conditions such as vascular and inflammatory skin diseases.

These findings have spurred the development of diagnostic technologies that use skin as a barometer for health. For example, pulse oximeters clipped on to the fingertip (used extensively during the pandemic) gauge a person’s blood oxygen levels. Accurate measurements of the skin microcirculation could also be used to alert to conditions from infections and inflammation to diabetes and heart disease.

However, most existing methods for measuring the microcirculation remain unreliable and expensive, a problem that Malini Olivo, Director of Biophotonics at A*STAR’s Institute of Bioengineering and Bioimaging (IBB), hopes to change by “listening” to the skin.

“When exposed to a pulsing laser light, human tissues heat up slightly, emitting faint acoustic waves. Through the detection of these waves, we can interrogate deeper into tissues as compared with using conventional methods that detect light signals,” explained Olivo, referring to a technique known as optoacoustic imaging, or OAI.

The team employed a specialised technique known as multispectral raster-scanning optoacoustic mesoscopy (ms-RSOM)—a first-of-its-kind OAI that takes high-resolution images at millimetre depths beneath the surface of the skin. The researchers then validated the technology on a cohort of six healthy participants, through collaborations with the National Skin Centre.

Using a blood pressure cuff to simulate blood flow changes caused by various illnesses, the researchers captured images before, during and after cuff compression. The team found that ms-RSOM accurately captured even subtle physiological changes in the microcirculation across different stages of occlusion.

This is the first demonstration that ms-RSOM can accurately track disruptions to the flow of oxygenated and deoxygenated blood within the vessels, which Olivo describes as a “window of opportunity” for clinicians to non-invasively diagnose and monitor conditions associated with vascular remodelling.

Still, the current ms-RSOM iteration is not without its limitations. “Currently, the system can only image up to two millimetres below the skin and image quality is often affected by skin pigmentation,” said Olivo, whose team has their sights set on a next-generation system with brighter lights and more sensitive acoustic signal collection to improve the quality of data collected.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Bioengineering and Bioimaging (IBB).

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References

Attia, A.B.E., Moothanchery, M., Li, X., Yew, Y.W., Thng, S.T.G. et al. Microvascular imaging and monitoring of hemodynamic changes in the skin during arterial-venous occlusion using multispectral raster-scanning optoacoustic mesoscopy. Photoacoustics 22, 100268 (2021) | article

About the Researchers

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Malini Olivo

Distinguished Principal Scientist

A*STAR Skin Research Labs (A*SRL)
Malini Olivo is a Distinguished Principal Scientist at A*STAR Skin Research Labs (A*SRL) where she leads the Translational Biophotonics Laboratory. Concurrently, she is also an Adjunct Professor at the Lee Kong Chian School of Medicine, NTU; Department of Obstetrics & Gynaecology, National University Health System, NUS, Singapore; and Royal College of Surgeons Ireland, Dublin, Ireland. She obtained a PhD degree in Bio-Medical Physics in 1990 from University Malaya/University College London (UCL) and did her post-doctoral training between 1991 and 1995 at UCL, UK and both McMaster University and University of Toronto, Canada. Her current research interest is in medtech and nano-biophotonics and its applications in translational medicine. Her efforts include bridging the gap between cutting edge optical technologies and unmet clinical needs by developing in-house photonics-based devices for various industries. She has succeeded in obtaining competitive research funding of over USD 25 million to support her research in Singapore and overseas. She has published over 500 papers, three books and 20 book chapters, and filed close to 50 patents on technology platforms and devices. She is also the co- founder of three medtech companies. Furthermore, she holds many advisory international roles and is well recognised internationally for her research in biophotonics for her pioneering research contributions. She has conferred as the Fellow of Optical Society of America (OSA), Fellow of American Institute of Medical Bioengineering (AIMBE) and Fellow of Institute of Physics, UK.
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Dinish U.S

Group Leader, Translational Biophotonics Laboratory (TBL)

A*STAR Skin Research Labs (A*SRL)
Dinish U.S is the Group Leader in Translational Biophotonics Laboratory at A*STAR Skin Research Labs (A*SRL). He also holds a joint adjunct faculty position at the School of Physical and Mathematical Sciences (SPMS), Nanyang Technological University (NTU), Singapore. He has extensive expertise in various preclinical and clinical studies using Photoacoustic imaging (PAI), diffuse reflectance spectroscopy (DRS), Raman spectroscopy, surface enhanced Raman scattering (SERS), fluorescence imaging and multimodal imaging approaches. Notably, Dinish has been actively involved in pioneering ‘first in human’ clinical studies that employ PAI for diagnosing skin cancer and inflammatory conditions. He is the PI and Co-PI of numerous national and international research grants. He is currently the editorial board member of ‘Scientific Reports’ (Nature Publishing Group).

This article was made for A*STAR Research by Wildtype Media Group