Deoxyhemoglobin Hb Research Articles

Learned spectral decoloring enables photoacoustic oximetry

The ability of photoacoustic imaging to measure functional tissue properties, such as blood oxygenation sO_2, enables a wide variety of possible applications. sO_2 can be computed from the ratio of oxyhemoglobin HbO_2 and deoxyhemoglobin Hb, which can be distuinguished by multispectral photoacoustic imaging due to their distinct wavelength-dependent absorption. However, current methods for estimating sO_2 yield inaccurate results in realistic settings, due to the unknown and wavelength-dependent influence of the light fluence on the signal. In this work, we propose learned spectral decoloring to enable blood oxygenation measurements to be inferred from multispectral photoacoustic imaging. The method computes sO_2 pixel-wise, directly from initial pressure spectra S_{text {p}_0}(lambda , mathbf {x}), which represent initial pressure values at a fixed spatial location mathbf {x} over all recorded wavelengths lambda. The method is compared to linear unmixing approaches, as well as pO_2 and blood gas analysis reference measurements. Experimental results suggest that the proposed method is able to obtain sO_2 estimates from multispectral photoacoustic measurements in silico, in vitro, and in vivo.

Mössbauer study of the time evolution of the biochemical composition of the hematomas. Relationship with magnetic resonance imaging (MRI)

Biochemical constitution of the hematoma is depending of its evolution. In order to obtain a reliable diagnostic of the NMR images in case of vascular accidents, a systematic study of the time-evolution of hematomas has been performed, using Mossbauer spectrometry and complementary technics (ESR and visible absorption spectrophotometry). The change, in the course of time, of HbO2 in deoxyhemoglobin Hb and other denaturation products (MHb, hemi- and hemochromes,…) are well-recognized on the different spectra.T1 andT2 NMR relaxation times are measured in the same time and their shortening is related to the appearance of the paramagnetic denaturation blood compounds.

Electronic structure of ferrous iron in hemoglobin inferred from Mössbau measurements.

The effect of rhombic perturbation on the low-lying energy levels (calculated for tetragonal point symmetry) of ferrous iron in deoxyhemoglobin Hb(rat, pH = 10) is investigated. The resulting temperature dependent electric-field gradient is compared with experimental values in order to get information about the energy-term scheme. The rhombic perturbation is shown to be small, leading to the splitting of the orbital doublet E5 by less than 400 cm−1. Application is made to the magnetic susceptibility which is calculated by means of the electronic structure inferred from the quadrupole splitting data.