In vivo real-time imaging of cutaneous hemoglobin concentration, oxygen saturation, scattering properties, melanin content, and epidermal thickness with visible spatially modulated light

Abstract

Abstract:We present the real-time single snapshot multiple frequency demodulation -spatial frequency domain imaging (SSMD-SFDI) platform implemented with a visible digital mirror device that is capable of imaging and monitoring dynamic turbid medium and processes over a large field of view. One challenge in quantitative imaging of biological tissue such as the skin is the complex structure rendering techniques based on homogeneous medium models to fail. To address this difficulty we have also developed a novel method that maps the layered structure to a homogeneous medium for spatial frequency domain imaging. The varying penetration depth of spatially modulated light on its wavelength and modulation frequency is used to resolve the layered structure. The efficacy of the real-time SSMD-SFDI platform and this two-layer model is demonstrated by imaging forearms of 6 healthy subjects under the reactive hyperemia protocol. The results show that our approach not only successfully decouples light absorption by melanin from that by hemoglobin and yields accurate determination of cutaneous hemoglobin concentration and oxygen saturation, but also provides reliable estimation of the scattering properties, the melanin content and the epidermal thickness in real time. Potential applications of our system in imaging skin physiological and functional states, cancer screening, and microcirculation monitoring are discussed at the end.

Monitoring of Hemodynamics in Human Skin Using Pulsed Photothermal Radiometry and Optical Spectroscopy

“…This supports our earlier experience with the same or very similar analyses, also including other volunteers [1][2][3]9,10]. Specifically, e.g., the fractional blood content is higher in the papillary as compared to reticular dermis, while the oxygenation level in the former is lower, in agreement with earlier reports from other groups [11,12].…”

Multi-beam scan analysis with a clinical LINAC for high resolution Cherenkov-excited molecular luminescence imaging in tissue

“…While the ultimate extent of compressed sensing methods uses complex patterns, the methodology for this could include a simpler spatial-frequency-domain imaging (SFDI) approach or more complex techniques such as used in coded aperture imaging (CAI). Current SFDI instruments typically use projected spatially modulated light, projected onto the sample, and then knowledge of the illumination patterns are used to demodulate the images [ 16 – 18 ]. CAI requires a coded mask placed either, in front of the radiation beam source to shape the incident beam, and at the detector to block the transmitted beam and disambiguate scatter angles [ 19 – 21 ].…”

Analysis of skin morphological features and real-time monitoring using snapshot hyperspectral imaging

“…Hemoglobin and melanin are the primary light absorbers in the skin [23][24][25][26]. The oxygenated and de-oxygenated hemoglobin exhibit distinct absorption curves across the visible wavelength window.…”