Noninvasive Assessment of Regional and Temporal Variations in Tissue Oxygenation by Near-Infrared Spectroscopy and Imaging

Abstract

A combination of near-infrared spectroscopy and discrete wavelength near-infrared imaging is used to noninvasively monitor the forearm during periods of restricted blood outflow (venous outflow restriction) and interrupted blood inflow (ischemia). Multivariate analysis of image and spectral data time courses was used to identify highly correlated spectral and regional domains, while fuzzy C-means clustering of image time courses was used to reveal finer regional heterogeneities in the response of stressed tissues. Localized near-infrared spectroscopy was used to investigate the magnitude of the bulk changes in the tissue optical properties and the variation in tissue oxygenation saturation during venous outflow restriction and complete forearm ischemia. The imaging and spectroscopic analyses revealed highly localized regional variations in tissue oxygen saturation during forearm ischemia as compared to the more diffuse and global response of the forearm during venous outflow restriction.

Mapping the myoglobin concentration, oxygenation, and optical pathlength in heart ex vivo using near-infrared imaging

“…The mapping of subepicardial hemoglobin (Hb) 1 + myoglobin (Mb) oxygenation in pig hearts has been reported using a near-infrared (NIR) spectroscopic imaging technique that, however, does not provide absolute concentrations and is limited to the oxygen saturation parameter (OSP) only [1], [2], [3], [4] and [5]. In spite of these limitations, the efficiency of this approach in cardiac research has been shown to be significant [6], [7] and [8].…”

Interpreting diffuse reflectance for in vivo skin reactions in terms of chromophores

“…coherence tomography [3], Raman [4][5][6] and infrared microscopies and macroscopic imaging [7][8][9], two-and three-photon microscopy [10][11][12], CARS (Coherent Anti-Stokes Raman Scattering) microscopy [13,14], and combinations of some of these. In particular diffuse reflectance spectroscopy (DRS) has been a useful tool to investigate the identification and concentration of absorbing chemical species (chromophores) and the way that absorption and scattering may influence each other in the skin.…”

Analysis and interpretation of infrared microscopic maps: Visualization and classification of skin components by digital staining and multivariate analysis

“…17 Full descriptions of the algorithms used can be found elsewhere. 13,18,19 Spectra were partitioned into clusters based on the known number of tissue constituents present.…”

“…FCM cluster analysis, as implemented in this study, identified regions of the tissue map that exhibited similar spectral responses. 13,18,19 Five discrete clusters of spectra were identified, and are superimposed on the spectroscopic map in Figure 4(C). The colors in Figure 4(C) relate to cluster, not to tissue component (as in the digital staining), and were chosen arbitrarily.…”