Quantitative depth analysis of optic nerve head using stereo retinal fundus image pair
Depth analysis of the optic nerve head (ONH) in the retinal fundus is important for the early detection of glaucoma. In this study, we investigate an automatic reconstruction method for the quantitati...
In vivo staining of neocortical astrocytes via the cerebral microcirculation using sulforhodamine B
Staining and imaging glial cells in vivo while observing the microvasculature could help understand brain physiology, namely neuronal-glial-vascular communication. Two-photon excitation microscopy pro...
Kathryn Osann University of California, Irvine, Department of Medicine, 1002 Health Sciences Road East, Irvine, California 92612
Matthew Brenner University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine California 92612 and University of California, Irvine Medical Center, Pulmonary and Critical Care Division, Building 53, Room 119, 101 City Drive South, Orange, California 92868
Wedemonstrate noninvasive near-infrared diffuse optical spectroscopy (DOS) measurements of tissuehemoglobin contents that can track progressive reductions in central bloodvolume in human volunteers. Measurements of mean arterial blood pressure(MAP), heart rate (HR), stroke volume (SV), and cardiac output(Q) are obtained in ten healthy human subjects during baselinesupine rest and exposure to progressive reductions of central bloodvolume produced by application of lower body negative pressure (LBNP).Simultaneous quantitative noninvasive measurements of tissue oxyhemoglobin (OHb), deoxyhemoglobin (RHb),total hemoglobin concentration (THb), and tissue hemoglobin oxygen saturation (StO2)are performed throughout LBNP application using broadband DOS. As progressivelyincreasing amounts of LBNP are applied, HR increases, and MAP,SV, and Q decrease (p<0.001). OHb, StO2, and THb decrease(p<0.001) in correlation with progressive increases in LBNP, while tissueRHb remained relatively constant (p=0.378). The average fractional changes frombaseline values in DOS OHb (fOHb) correlate closely with independentlymeasured changes in SV (r2=0.95) and Q (r2=0.98) during LBNP.Quantitative noninvasive broadband DOS measurements of tissue hemoglobin parameters ofperipheral perfusion are capable of detecting progressive reductions in centralblood volume, and appear to be sensitive markers of earlyhypoperfusion associated with hemorrhage as simulated by LBNP.
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