Transabdominal near infrared oximetry of hypoxic stress in fetal sheep brain
            <i>in utero</i>

Choe, Regine; Durdurán, Turgut; Yu, Guoqiang; Nijland, Mark J.; Chance, Britton; Yodh, Arjun G.; Ramanujam, Nirmala

doi:10.1073/pnas.1735462100

Cited by 41 publications

(28 citation statements)

References 43 publications

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“…Reflectance diffuse spectroscopy measurement of tissue oxygenation is a well-established methodology (21,32,34,(41)(42)(43)(44). In addition, validation of our diffuse optical reflectance approach in tissues has been reported in brain activation (33,45) and tumor studies (46).…”

Section: Resultsmentioning

confidence: 88%

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Treatment-Induced Changes in Tumor Oxygenation Predict Photodynamic Therapy Outcome

Putt²,

et al. 2004

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Photodynamic therapy (PDT) requires oxygen to cause tumor damage, yet therapy itself can deplete or enhance tumor oxygenation. In the present work we measured the PDT-induced change in tumor oxygenation and explored its utility for predicting long-term response to treatment. The tissue hemoglobin oxygen saturation (SO 2 ) of murine tumors was noninvasively measured by broadband diffuse reflectance spectroscopy. In initial validation studies, the oxyhemoglobin dissociation curve for mouse blood was accurately recreated based on measurements during deoxygenation of a tissue phantom of mouse erythrocytes. In vivo studies exhibited excellent correlation between carbogen-induced changes in SO 2 and pO 2 of radiation-induced fibrosarcoma tumors measured by reflectance spectroscopy and the Eppendorf pO 2 histograph, respectively. In PDT studies radiation-induced fibrosarcoma tumor SO 2 was measured immediately before and after Photofrin-PDT (135 J/cm 2 , 38 mW/cm 2 ). Animals were subsequently followed for tumor growth to a volume of 400 mm 3 (time-to-400 mm 3 ) or the presence of tumor cure (no tumor growth at 90 days after treatment). In animals that recurred, the PDT-induced change in tumor SO 2 , i.e., relative-SO 2 (SO 2 after PDT/SO 2 before PDT) was positively correlated with treatment durability (time-to-400 mm 3 ). The predictive value of relative-SO 2 was confirmed in a second group of animals with enhanced pre-PDT oxygenation due to carbogen breathing. Furthermore, when all of the animals were considered (those that recurred and those that were cured) a highly significant association was found between increasing relative-SO 2 and increasing probability of survival, i.e., absence of recurrence. As independent variables, the SO 2 after PDT, the pre-PDT tumor volume, and light penetration depth all failed to predict response. As an independent variable, the SO 2 before PDT demonstrated a weak negative association with treatment durability; this association was driven by a correlation between decreasing pre-PDT SO 2 and increasing relative-SO 2 . These data suggest that monitoring of PDTinduced changes in tumor oxygenation may be a valuable prognostic indicator.

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Section: Resultsmentioning

confidence: 88%

“…Reflectance diffuse spectroscopy is a well-documented technique of measuring tissue optical properties, including concentrations of oxyhemoglobin and deoxyhemoglobin (21,32,34,35,(41)(42)(43)(44). From these quantities tissue hemoglobin oxygen saturation, or SO 2 , can be calculated.…”

Section: Discussionmentioning

confidence: 99%

Treatment-Induced Changes in Tumor Oxygenation Predict Photodynamic Therapy Outcome

Putt²,

et al. 2004

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“…The importance of absolute measurements for in vivo interrogation of cerebrovascular health has been shown in animal models [35], [40], [41], [42]. Briefly, Saxena et al .…”

Section: Introductionmentioning

confidence: 99%

“…Finally, Choe et al . demonstrated that absolute values of [HbO 2 ] and [Hb] can be used to measure hypoxic stress in fetal sheep brain in utero and emphasized the potential implications of such measurements for the imaging of the human fetus [41]. Such diagnostic and/or long-term monitoring approaches presented above could only be made possible by quantification of concentration and saturation of hemoglobin in absolute terms.…”

Section: Introductionmentioning

confidence: 99%

Optical Characterization of Two-Layered Turbid Media for Non-Invasive, Absolute Oximetry in Cerebral and Extracerebral Tissue

2013

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We introduce a multi-distance, frequency-domain, near-infrared spectroscopy (NIRS) method to measure the optical coefficients of two-layered media and the thickness of the top layer from diffuse reflectance measurements. This method features a direct solution based on diffusion theory and an inversion procedure based on the Levenberg-Marquardt algorithm. We have validated our method through Monte Carlo simulations, experiments on tissue-like phantoms, and measurements on the forehead of three human subjects. The Monte Carlo simulations and phantom measurements have shown that, in ideal two-layered samples, our method accurately recovers the top layer thickness (L), the absorption coefficient (µa) and the reduced scattering coefficient (µ′s) of both layers with deviations that are typically less than 10% for all parameters. Our method is aimed at absolute measurements of hemoglobin concentration and saturation in cerebral and extracerebral tissue of adult human subjects, where the top layer (layer 1) represents extracerebral tissue (scalp, skull, dura mater, subarachnoid space, etc.) and the bottom layer (layer 2) represents cerebral tissue. Human subject measurements have shown a significantly greater total hemoglobin concentration in cerebral tissue (82±14 µM) with respect to extracerebral tissue (30±7 µM). By contrast, there was no significant difference between the hemoglobin saturation measured in cerebral tissue (56%±10%) and extracerebral tissue (62%±6%). To our knowledge, this is the first time that an inversion procedure in the frequency domain with six unknown parameters with no other prior knowledge is used for the retrieval of the optical coefficients and top layer thickness with high accuracy on two-layered media. Our absolute measurements of cerebral hemoglobin concentration and saturation are based on the discrimination of extracerebral and cerebral tissue layers, and they can enhance the impact of NIRS for cerebral hemodynamics and oxygenation assessment both in the research arena and clinical practice.

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“…Subsequently, an optical fetal heart rate detection (OFHR) system has been designed and developed using low-cost, low-power IR light (890 nm with optical power < 68 mW) and a commercially available silicon photo-detector ). Previous literature Chance 2005;Zourabian et al 2000;Nioka et al 2005;Vintzileos et al 2005;Choe et al 2003) shows that the Source-Detector separations depends on the type of sources and the photo-detectors implemented in their studies. Since in our work the developed instrument utilizes low optical power, the source-to-detector separation plays an important role as it affects the detectivity of the photo-detector.…”

Section: Adaptive Filtering Applications 142mentioning

confidence: 99%

Application of Adaptive Noise Cancellation in Transabdominal Fetal Heart Rate Detection Using Photoplethysmography

Beng¹,

Zahedi²,

Ali³

2011

Adaptive Filtering Applications

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Transabdominal near infrared oximetry of hypoxic stress in fetal sheep brain in utero

Cited by 41 publications

References 43 publications

Treatment-Induced Changes in Tumor Oxygenation Predict Photodynamic Therapy Outcome

Treatment-Induced Changes in Tumor Oxygenation Predict Photodynamic Therapy Outcome

Optical Characterization of Two-Layered Turbid Media for Non-Invasive, Absolute Oximetry in Cerebral and Extracerebral Tissue

Application of Adaptive Noise Cancellation in Transabdominal Fetal Heart Rate Detection Using Photoplethysmography

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