The phase-II application describes a systematic approach for the optimization and validation of trans-abdominal, near infrared (NIR) imaging of fetal cerebral blood saturation in utero. The phase-I accomplishments and additional preliminary investigations, demonstrate that it is possible to measure and quantify photon migration through the fetal head in utero, using continuous wave, NIR technology. The goal of the phase-II effort is to further optimize the NIR technology in order to enable quantitative, trans-abdominal, NIR imaging. First, a model based iterative image reconstruction (MOBIIR) scheme, will be adapted and optimized in conjunction with experimental and theoretical models for measurement geometries and data types, appropriate for trans-abdominal, NIR imaging. Next, two, complementary, dual wavelength, NIR devices will be optimized for trans-abdominal, NIR imaging. The first instrument will be a frequency domain device, with multiple source-detector pairs. The amplitude attenuation and phase delay in the tissue, measured with this device, will be incorporated in the MOBIIR scheme to quantify the blood saturation of the maternal and fetal tissues. The second instrument is a previously developed, continuous wave device. The amplitude modulation due to the fetal and maternal arterial pulses, measured with this device, will be incorporated into an algorithm based on pulse oximetry to extract the maternal and fetal arterial blood saturation. The accuracy and sensitivity of the two devices and corresponding analysis schemes will be validated using the near-term, pregnant ewe model. The feasibility of performing trans-abdominal, NIR imaging of fetal cerebral blood saturation in utero, will be evaluated in near-term patients.
Trans-abdominal, NIR imaging has the potential to assess fetal well being in near term, patients and patients during early labor (prior to descent of the fetal head). Fetal cerebral blood saturation obtained from trans- abdominal, NIR imaging in near-term patients or from patients in early labor can be used as an analog to scalp pH (which is generally obtained later in labor) to determine whether less aggressive or more aggressive clinical intervention is required. A low reading indicating fetal compromise could warrant the need for a cesarean delivery, while a normal reading could allow for the normal progression of labor. Trans- abdominal, NIR imaging may be particularly useful in early labor because during this period, the clinician may be confronted with non-reassuring fetal testing, but is unable to perform an NST, BPP (generally believed to be uninterpretable in labor), fetal scalp pH or internal monitoring (which requires cervical dilatation). Preventing the cesarean delivery of uncompromised fetuses (both premature and mature) in this manner, could have tremendous economic and medical benefits in the health care of children and mothers.
| Ren, Kui; Abdoulaev, Gassan S; Bal, Guillaume et al. (2004) Algorithm for solving the equation of radiative transfer in the frequency domain. Opt Lett 29:578-80 |
| Bluestone, A Y; Stewart, M; Lasker, J et al. (2004) Three-dimensional optical tomographic brain imaging in small animals, part 1: hypercapnia. J Biomed Opt 9:1046-62 |
| Hielscher, A H; Bluestone, A Y; Abdoulaev, G S et al. (2002) Near-infrared diffuse optical tomography. Dis Markers 18:313-37 |
