Effects of skin tone on photoacoustic imaging and oximetry
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Significance: Photoacoustic imaging (PAI) provides contrast based on the concentration of optical absorbers in tissue, enabling the assessment of functional physiological parameters such as blood oxygen saturation (sO2). Recent evidence
suggests that variation in melanin levels in the epidermis leads to measurement
biases in optical technologies, which could potentially limit the application of these
biomarkers in diverse populations.
Aim: To examine the effects of skin melanin pigmentation on PAI and oximetry.
Approach: We evaluated the effects of skin tone in PAI using a computational skin
model, two-layer melanin-containing tissue-mimicking phantoms, and mice of a con sistent genetic background with varying pigmentations. The computational skin
model was validated by simulating the diffuse reflectance spectrum using the add ing-doubling method, allowing us to assign our simulation parameters to approxi mate Fitzpatrick skin types. Monte Carlo simulations and acoustic simulations
were run to obtain idealized photoacoustic images of our skin model. Photoacoustic
images of the phantoms and mice were acquired using a commercial instrument.
Reconstructed images were processed with linear spectral unmixing to estimate
blood oxygenation. Linear unmixing results were compared with a learned unmixing
approach based on gradient-boosted regression.
Results: Our computational skin model was consistent with representative literature
for in vivo skin reflectance measurements. We observed consistent spectral coloring
effects across all model systems, with an overestimation of sO2 and more image
artifacts observed with increasing melanin concentration. The learned unmixing
approach reduced the measurement bias, but predictions made at lower blood
sO2 still suffered from a skin tone-dependent effect.
Conclusion: PAI demonstrates measurement bias, including an overestimation of
blood sO2, in higher Fitzpatrick skin types. Future research should aim to characterize this effect in humans to ensure equitable application of the technology.
suggests that variation in melanin levels in the epidermis leads to measurement
biases in optical technologies, which could potentially limit the application of these
biomarkers in diverse populations.
Aim: To examine the effects of skin melanin pigmentation on PAI and oximetry.
Approach: We evaluated the effects of skin tone in PAI using a computational skin
model, two-layer melanin-containing tissue-mimicking phantoms, and mice of a con sistent genetic background with varying pigmentations. The computational skin
model was validated by simulating the diffuse reflectance spectrum using the add ing-doubling method, allowing us to assign our simulation parameters to approxi mate Fitzpatrick skin types. Monte Carlo simulations and acoustic simulations
were run to obtain idealized photoacoustic images of our skin model. Photoacoustic
images of the phantoms and mice were acquired using a commercial instrument.
Reconstructed images were processed with linear spectral unmixing to estimate
blood oxygenation. Linear unmixing results were compared with a learned unmixing
approach based on gradient-boosted regression.
Results: Our computational skin model was consistent with representative literature
for in vivo skin reflectance measurements. We observed consistent spectral coloring
effects across all model systems, with an overestimation of sO2 and more image
artifacts observed with increasing melanin concentration. The learned unmixing
approach reduced the measurement bias, but predictions made at lower blood
sO2 still suffered from a skin tone-dependent effect.
Conclusion: PAI demonstrates measurement bias, including an overestimation of
blood sO2, in higher Fitzpatrick skin types. Future research should aim to characterize this effect in humans to ensure equitable application of the technology.
Date Issued
2024-01-01
Date Acceptance
2023-11-28
Citation
Journal of Biomedical Optics, 2024, 29 (S1)
ISSN
1083-3668
Publisher
SPIE-Intl Soc Optical Eng
Journal / Book Title
Journal of Biomedical Optics
Volume
29
Issue
S1
Copyright Statement
© The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/38125716
PII: 230232SSR
Subjects
Fitzpatrick skin types
melanin
photoacoustic imaging
racial bias
spectral unmixing
Humans
Animals
Mice
Skin Pigmentation
Oxygen
Melanins
Photoacoustic Techniques
Oximetry
Phantoms, Imaging
Publication Status
Published
Coverage Spatial
United States
Article Number
S11506
Date Publish Online
2023-12-20