Estimation of porcine pancreas optical properties in the 600–1100 nm wavelength range for light-based therapies

Abstract

This work reports the optical properties of porcine pancreatic tissue in the broad wavelength range of 600–1100 nm. Absorption and reduced scattering coefficients (µa and µs′) of the ex vivo pancreas were obtained by means of Time-domain Diffuse Optical Spectroscopy. We have investigated different experimental conditions—including compression, repositioning, spatial sampling, temporal stability—the effect of the freezing procedure (fresh vs frozen-thawed pancreas), and finally inter-sample variability. Good repeatability under different experimental conditions was obtained (median coefficient of variation less than 8% and ~ 16% for µa and µs′, respectively). Freezing–thawing the samples caused an irreversible threefold reduction of µs′ and no effect on µa. The absorption and reduced scattering spectra averaged over different samples were in the range of 0.12–0.74 cm−1 and 12–21 cm−1 with an inter-sample variation of ~ 10% and ~ 40% for µa and µs′, respectively. The calculated effective transport coefficient (µeff) for fresh pancreatic tissue shows that regions between 800–900 nm and 1050–1100 nm are similar and offer the lowest tissue attenuation in the considered range (i.e., µeff ranging from 2.4 to 2.7 cm−1). These data, describing specific light-pancreas interactions in the therapeutic optical window for the first time, provide pivotal information for planning of light-based thermotherapies (e.g., laser ablation) and instruction of light transport models for biophotonic applications involving this organ.

Temperature Dependence of Thermal Properties of Ex Vivo Porcine Heart and Lung in Hyperthermia and Ablative Temperature Ranges

“…We first performed a preliminary analysis on the thermal properties of fresh and frozen-thawed tissue, at different selected temperatures, which highlighted no substantial differences between the tissues undergoing these different conservation protocols. The attained results are in accordance with previous experiments on different biological media (i.e., pancreas tissues) which showed, differently from other physical properties such as optical properties 3 , 35 , no significant variation in terms of thermal conductivity for fresh and frozen (for 7 and for 14 days) specimens. 3 These results may be useful for the improvement of laboratory protocols regarding tissue conservation for better accountability of experimental measurements.…”

Optical rogue waves in spheroids of tumor cells

“…The measured diffuse reflectance is ≈ 0.3, which suggests that light propagation is governed by diffusive transport [34]. At the operating wavelength, the measured absorption coefficient of the bioprinted spheroids without culture is ≈ 0.5 cm −1 , comparable with similar pancreatic tissues that are strongly diffusive [35]. We hence expect the wave propagation to be described by a random Gaussian process for the field amplitude (random wave theory, RWT), which results in the Rayleigh statistics [36].…”

Temporal evolution of optical properties at different temperatures of biological tissues

“…We measured the optical properties using a broadband time-resolved diffuse optical spectroscopy system based on a supercontinuum laser and single-photon detection. 5 We measured in reflectance configuration at 1 cm, 2 cm, and 3 cm of source detection (SD) separation. A Silicon photomultiplier recorded the photons' arrival.…”