Modeling photon transport in transabdominal fetal oximetry

Jacques, Steven L.; Ramanujam, Nirmala; Vishnoi, Gargi; Choe, Regine; Chance, Britton

doi:10.1117/1.429996

Cited by 22 publications

(13 citation statements)

References 9 publications

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“…Subsequently, Zourabian et al developed a transabdominal NIR CW oximeter with the capability to detect fetal arterial pulses in utero [301]. In addition, theoretical and experimental tissue phantom investigations have been performed to understand NIR photon diffusion through the fetal brain in utero [138,270]. Collectively, these studies suggest transabdominal NIR photon diffusion measurements through the fetal brain in utero are possible.…”

Section: Fetal Brain Oxygenation Monitoringmentioning

confidence: 99%

Diffuse optical tomography and spectroscopy of breast cancer and fetal brain

Choe

2005

Medical Physics

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Diffuse optical techniques utilize light in the near infrared spectral range to measure tissue physiology noninvasively. Based on these measurements, either average bulk optical properties or threedimensional spatial maps of tissue properties such as total hemoglobin concentration, blood oxygen saturation and scattering can be obtained using model-based reconstruction algorithms. In this thesis, diffuse optical techniques were applied for in vivo breast cancer imaging and transabdominal fetal brain oxygenation monitoring. For clinical in vivo breast cancer imaging, diffuse optical tomography technique and related instrumentation were developed. The clinical diffuse optical tomography instrument utilized near infrared light sources of multiple wavelengths, and multiple source-detector positions in a parallel plate geometry. Transmission continuous-wave measurements by a lens-coupled CCD camera and remission frequency-domain measurements by fiber-coupled detector channels were performed simultaneously. Human subject measurements were carried out in the prone position. The breast was softly compressed and the space adjacent to the breast was filled with a matching fluid with similar optical properties to that of the breast. A nonlinear conjugate gradient inverse algorithm with a priori spectral constraints was utilized to reconstruct threedimensional endogeneous optical and physiological breast properties. Bulk physiological properties were quantified for 52 healthy subjects in the parallel-plate transmission geometry. Threedimensional images of the breast were reconstructed for 21 subjects with breast carcinomas. Tumor contrast with respect to normal tissue was found in total hemoglobin concentration and scattering coefficient. An optical index combining total hemoglobin concentration and scattering coefficient shows the tumor contrast to be 2-3 times larger compared to the healthy tissue. Tumor contrast and tumor volume changes during neoadjuvant chemotherapy were tracked for one subject and compared to the dynamic contrast-enhanced magnetic resonance imaging ͑MRI͒. Our measurement revealed tumor shrinkage during the course of chemotherapy, in reasonable agreement with magnetic resonance images of the same subject. Finally, the feasibility of measuring blood flow of breast tumors using optical methods was demonstrated for seven subjects. In a qualitatively different set of experiments, the feasibility of transabdominal fetal brain oxygenation monitoring was demonstrated on pregnant ewes with induced transient fetal hypoxia. Preliminary noninvasive clinical measurements before and after human Cesarean sections were discussed, identifying future directions. Overall, this research has translated diffuse optical tomography techniques into a clinical research environment.

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Section: Fetal Brain Oxygenation Monitoringmentioning

confidence: 99%

Diffuse optical tomography and spectroscopy of breast cancer and fetal brain

Choe

2005

Medical Physics

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“…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.…”

Section: Nirs In Obstetrics and Neonatologymentioning

confidence: 99%

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

Acton

Goswami

McKenna

2013

Congenital Anomalies

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A myriad of factors have been linked to increased risk for intrauterine growth restriction and the associated complications; the majority of which are based on observational statistics of demographics, socioeconomics and patient history. Unfortunately, there is a paucity of factors available that can appropriately address the underlying anatomy and physiology responsible for intrauterine growth restriction. To this point, it becomes necessary to use data acquisition modalities capable of addressing both the etiology and pathology in an effort to improve clinical management strategies. Near-infrared spectroscopy, although not traditionally used in standard, clinical screening has proven valuable for risk assessment in a number of recent investigational studies. Simulations based on the current literature are presented to assess near infrared spectroscopy utility regarding the ability to distinguish between the normal fetus and the growth restricted fetus. Findings are presented for all simulated data as well as the equipment-specific data derived from the NIRO-100 system (Hamamatsu Photonics, Hamamatsu, Japan). Results suggest an overall sensitivity and specificity on the order of 62% and 58%, respectively, and NIRO-100 sensitivity and specificity on the order of 85% and 92%, respectively.

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“…Previous studies have demonstrated, through simulations, [18][19][20][21][22] phantom models, 23 and in vivo experiments, 22,24 the feasibility of detecting NIR photons that have penetrated an underlying fetal layer, centimeters deep. There has been a discussion among investigators as to which photon diffusion model most accurately describes photon propagation through a two-layer model, 11,12,14,16,22 such as that described here.…”

Section: Introductionmentioning

confidence: 99%

Effect of errors in baseline optical properties on accuracy of transabdominal near-infrared spectroscopy in fetal sheep brain during hypoxic stress

et al. 2005

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A continuous-wave (cw) near-infrared spectroscopy (NIRS) instrument has been developed to noninvasively quantify fetal cerebral blood oxygen saturation (StO2). A linear Green's function formulism was used to analytically solve the photon diffusion equation and extract the time-varying fetal tissue oxy- and deoxy-hemoglobin concentrations from the NIR measurements. Here we explored the accuracy with which this instrument can be expected to perform over a range of fetal hypoxic states. We investigated the dependence of this accuracy on the accuracy of the reference optical properties chosen based on the literature. The fetal oxygenation of a pregnant ewe model was altered via maternal aortic occlusion. The NIR cw instrument was placed on the maternal abdomen directly above the fetal head, continuously acquiring diffuse optical measurements. Blood was sampled periodically from the fetus to obtain fetal arterial saturation (SaO2) measurements from blood gas analysis. The NIR StO2 values were compared with the fetal SaO2 measurements. Variations in the NIR results due to uncertainty in the reference optical properties were relatively small within the fetal SaO2 range of 30 to 80%. Under hypoxic conditions, however, the variability of the NIR StO2 calculations with changes in the assumed reference properties became more significant.

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Modeling photon transport in transabdominal fetal oximetry

Cited by 22 publications

References 9 publications

Diffuse optical tomography and spectroscopy of breast cancer and fetal brain

Diffuse optical tomography and spectroscopy of breast cancer and fetal brain

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

Effect of errors in baseline optical properties on accuracy of transabdominal near-infrared spectroscopy in fetal sheep brain during hypoxic stress

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