Photon migration through fetal head in utero using continuous wave, near infrared spectroscopy: clinical and experimental model studies

Abstract

Near infrared (NIR) measurements were made from the maternal abdomen (clinical studies) and laboratory tissue phantoms (experimental studies) to gain insight into photon migration through the fetal head in utero. Specifically, a continuous wave spectrometer was modified and employed to make NIR measurements at 760 and 850 nm, at a large (10 cm) and small (2.5/4 cm) source-detector separation, simultaneously, on the maternal abdomen, directly above the fetal head. A total of 19 patients were evaluated, whose average gestational age and fetal head depth, were 37 weeks +/- 3 and 2.25 cm +/- 0.7, respectively. At the large source-detector separation, the photons are expected to migrate through both the underlying maternal and fetal tissues before being detected at the surface, while at the short source-detector separation, the photons are expected to migrate primarily through the superficial maternal tissues before being detected. Second, similar NIR measurements were made on laboratory tissue phantoms, with variable optical properties and physical geometries. The variable optical properties were obtained using different concentrations of India ink and Intralipid in water, while the variable physical geometries were realized by employing glass containers of different shapes and sizes. Third, the NIR measurements, which were made on the laboratory tissue phantoms, were compared to the NIR measurements made on the maternal abdomen to determine which tissue phantom best simulates the photon migration path through the fetal head in utero. The results of the comparison were used to provide insight into the optical properties and physical geometry of the maternal and fetal tissues in the photon migration path.

Critical computational aspects of near infrared circular tomographic imaging: Analysis of measurement number, mesh resolution and reconstruction basis

“…In the recent years, there has been a heightened interest in near-infra-red (NIR) optical tomography, for applications such as diagnostic breast cancer imaging [1-3] and for brain function assay [1,4,5]. In NIR tomography, the aim is to reconstruct interior optical properties of the tissue under investigation from a finite, yet incomplete set of transmission measurements taken at the tissue external boundaries.…”

Utility of near infrared spectroscopy for the screening of the growth restricted fetus

“…The use of NIRS in neonatology and obstetrics dates back to the mid 1980s and has been used for interrogation of both fetal and maternal tissues in all stages of pregnancy (Brazy et al 1985;O'Brien et al 1992;Baños et al 2007). Antepartum NIRS, the application currently under investigation, began with photon migration studies (Jacques et al 2000;Ramanujam et al 2000;Vishnoi et al 2000), and has since matured into a means of monitoring fetal and placental tissues in utero via spatially resolved, transabdominal NIRS.…”

Determination of Reflectance Optical Sensor Array Configuration Using 3-Layer Tissue Model and Monte Carlo Simulation

“…The use of optical sensor method in detecting and measuring the fetal oximetry or heart rate applications has been adopted by many researchers [2][3][4][5]. There are a few available commercial optical sensors for fetal oximetry in the market but all inherit the same limitation; the technique is invasive to mothers.…”