| 1. |
- Afshari, Ali, et al.
(författare)
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Evaluation of the robustness of cerebral oximetry to variations in skin pigmentation using a tissue-simulating phantom
- 2022
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Ingår i: Biomedical Optics Express. - Washington, DC, United States : Optica Publishing Group. - 2156-7085. ; 13:5, s. 2909-2928
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Tidskriftsartikel (refereegranskat)abstract
- Clinical studies have demonstrated that epidermal pigmentation level can affect cerebral oximetry measurements. To evaluate the robustness of these devices, we have developed a phantom-based test method that includes an epidermis-simulating layer with several melanin concentrations and a 3D-printed cerebrovascular module. Measurements were performed with neonatal, pediatric and adult sensors from two commercial oximeters, where neonatal probes had shorter source-detector separation distances. Referenced blood oxygenation levels ranged from 30 to 90%. Cerebral oximeter outputs exhibited a consistent decrease in saturation level with simulated melanin content; this effect was greatest at low saturation levels, producing a change of up to 15%. Dependence on pigmentation was strongest in a neonatal sensor, possibly due to its high reflectivity. Overall, our findings indicate that a modular channel-array phantom approach can provide a practical tool for assessing the impact of skin pigmentation on cerebral oximeter performance and that modifications to algorithms and/or instrumentation may be needed to mitigate pigmentation bias.
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| 2. |
- Grant, Alexander M., et al.
(författare)
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Diffuse optical spectroscopy of melanoma-simulating silicone phantoms
- 2009
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Ingår i: PROCEEDINGS VOLUME 7187 SPIE BIOS, 24-29 JANUARY 2009 Biomedical Applications of Light Scattering III. - : SPIE - International Society for Optical Engineering. - 9780819474339 ; , s. 718702-1-718702-12
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Konferensbidrag (refereegranskat)abstract
- Currently the only method for positively identifying malignant melanoma involves invasive and often undesirable biopsy procedures. Available ex-vivo data indicates increased vascularization in the lower regions of excised melanoma, as compared to dysplastic nevi. The ability to interrogate this region of tissue in-vivo could lead to useful diagnostic information. Using a newly developed fiber based superficial probe in conjunction with a steady-state frequency-domain photon migration (SSFDPM) system, we can probe the upper 1-2 mm of tissue, extracting functional information in the near infrared (650-1000 nm) range. To test the resolution and detection range of the superficial probe in this context, deformable silicone phantoms have been fabricated that simulate normal skin with melanocytic lesions. These phantoms consist of a two-layered matrix with the optical properties of normal light skin, containing several cylindrical inclusions that simulate highly absorbing pigmented lesions such as melanoma. These inclusions are varied in depth, diameter, and optical properties in order to fully test the probe's detection capabilities. It was found that, depending on absorption, we can typically probe to a depth of 1.0-1.5 mm in an inclusion, likely reaching the site of angiogenesis in an early-stage melanoma. Additionally, we can successfully interrogate normal tissue below lesions 1.5mm deep when absorption is about 0.4/mm or less. This data indicates that the superficial probe shows great promise for non-invasive diagnosis of pigmented lesions.
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