Spatially confined and temporally resolved refractive index and scattering evaluation in human skin performed with optical coherence tomography

Knüttel, A.; Boehlau-Godau, M

doi:10.1117/1.429972

Cited by 224 publications

(169 citation statements)

References 22 publications

(27 reference statements)

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“…Cutaneous red blood cell flux varies between comparable sites in the same individual, and 1-mm 2 areas of vascular "territories" surrounded in part by relatively avascular areas have been identified in human skin (35)(36)(37). An optical coherence tomography study of human skin showed pockets of different refractive index values in the skin (38 ). Thus, even if the shape of the MTT curve is tracking the change in glucose concentration, a constant-term difference may result from positioning of the illumination and detection fibers with respect to vascular territories and avascular areas in the skin, and/or with respect to pockets with different refractive index values.…”

Section: Discussionmentioning

confidence: 99%

Monitoring Blood Glucose Changes in Cutaneous Tissue by Temperature-modulated Localized Reflectance Measurements

2003

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Background: Most proposed noninvasive methods for glucose measurements do not consider the physiologic response of the body to changes in glucose concentration. Rather than consider the body as an inert matrix for the purpose of glucose measurement, we exploited the possibility that noninvasive measurements of glucose can be approached by investigating their effects on the skin's thermo-optical response. Methods: Glucose concentrations in humans were correlated with temperature-modulated localized reflectance signals at wavelengths between 590 and 935 nm, which do not correspond to any near-infrared glucose absorption wavelengths. Optical signal was collected while skin temperature was modulated between 22 and 38°C over 2 h to generate a periodic set of cutaneous vasoconstricting and vasodilating events, as well as a periodic change in skin light scattering. The method was tested in a series of modified meal tolerance tests involving carbohydrate-rich meals and no-meal or highprotein/no-carbohydrate meals. Results: The optical data correlated with glucose values. Changes in glucose concentrations resulting from a carbohydrate-rich meal were predicted with a model based on a carbohydrate-meal calibration run. For diabetic individuals, glucose concentrations were predicted with a standard error of prediction <1.5 mmol/L and a prediction correlation coefficient 0.73 in 80% of the cases. There were run-to-run differences in predicted glucose concentrations. Non-carbohydrate meals showed a high degree of scatter when predicted by a carbohydrate meal calibration model. Conclusions: Blood glucose concentrations alter thermally modulated optical signals, presumably through physiologic and physical effects. Temperature changes

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Section: Discussionmentioning

confidence: 99%

Monitoring Blood Glucose Changes in Cutaneous Tissue by Temperature-modulated Localized Reflectance Measurements

2003

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“…Knüttel et al expanded Tearney's focus tracking method to measure depth-resolved changes of the refractive index [131]. Based on the model by Thrane et al relating the OCT signal strength to scattering [132], Letvitz et al extracted the scattering coefficient and the effective anisotropy factor from OCT A-scans [133], and Turchin et al developed an algorithm to derive the scattering coefficients of multi-layer samples [134].…”

Section: Measurement Of Bulk Optical Propertiesmentioning

confidence: 99%

Optical coherence tomography—current technology and applications in clinical and biomedical research

et al. 2011

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Optical coherence tomography (OCT) is a non-invasive imaging technique providing real-time twoand three-dimensional images of scattering samples with micrometer resolution. Mapping the local reflectivity, OCT visualizes the morphology of the sample. In addition, functional properties such as birefringence, motion or the distribution of certain substances can be detected with high spatial resolution. The main field of application is bio-medical imaging and diagnostics. In ophthalmology, OCT is accepted as a clinical standard for diagnosing and monitoring treatment of a number of retinal diseases, and OCT is becoming an important instrument for clinical cardiology. New applications are emerging in various medical fields, e. g. early-stage cancer detection, surgical guidance, and early diagnosis of musculoskeletal diseases. OCT has also proven its value as a tool for developmental biology. The number of companies involved in manufacturing OCT systems has increased substantially during the last years-especially due to its success in opthalmology-and this technology can be expected to continue to spread into various fields of application.

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“…One of the optical parameters that can be directly measured for biological tissues is the average refractive index of the tissue [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. In the literature, one can find estimates of the average refractive index for many types of tissues (cornea, sclera, dermis, epidermis, brain tissue etc.…”

Section: Introductionmentioning

confidence: 99%

Average refractive index of tendon as a function of water content

Shvachkina

Yakovlev

Pravdin

2018

J-BPE

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Abstract. Experimental data on the dependence of the average refractive index of rat tail tendon (RTT) on water content are reported. Using optical coherence tomography, the average group refractive index (at a wavelength of 930 nm) and cross-section area of rat tail tendon fascicle specimens during their air-drying and rehydration were monitored. The dependence of the average group refractive index of RTT (ng) on the volume fraction of water (Cw) has been found to be nonlinear and to be well approximated by the quadratic polynomial ng = 1.5713 -0.1969Cw -0.0328(Cw) 2 . The reported data are shown to be in good agreement with previously published data for bovine cornea.

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Spatially confined and temporally resolved refractive index and scattering evaluation in human skin performed with optical coherence tomography

Cited by 224 publications

References 22 publications

Monitoring Blood Glucose Changes in Cutaneous Tissue by Temperature-modulated Localized Reflectance Measurements

Monitoring Blood Glucose Changes in Cutaneous Tissue by Temperature-modulated Localized Reflectance Measurements

Optical coherence tomography—current technology and applications in clinical and biomedical research

Average refractive index of tendon as a function of water content

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