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Measuring the global cerebral metabolic rate of oxygen (CMRO(2)) is a valuable tool for assessing brain vitality and function. Measurement of blood oxygen saturation (HbO(2)) and flow in the major cerebral outflow and inflow vessels can provide a global estimate of CMRO(2). We demonstrate a rapid noninvasive method for quantifying CMRO(2) by simultaneously(More)
Several subtypes of melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) have been reported. The M1 type of ipRGCs exhibit distinct properties compared with the remaining (non-M1) cells. They differ not only in their soma size and dendritic arbor, but also in their physiological properties, projection patterns, and functions.(More)
The effect of hypercapnia on cerebral metabolic rate of oxygen consumption (CMRO(2)) has been a subject of intensive investigation and debate. Most applications of hypercapnia are based on the assumption that a mild increase in partial pressure of carbon dioxide has negligible effect on cerebral metabolism. In this study, we sought to further investigate(More)
A time-efficient method is described for in vivo venous blood T(1) measurement using multiphase inversion-recovery-prepared balanced steady-state free precession imaging. Computer simulations and validation experiments using a flow phantom were carried out to demonstrate the accuracy of the proposed method for measuring blood T(1) by taking advantage of the(More)
Quantification of blood oxygen saturation on the basis of a measurement of its magnetic susceptibility demands knowledge of the difference in volume susceptibility between fully oxygenated and fully deoxygenated blood (Δχ(do) ). However, two very different values of Δχ(do) are currently in use. In this work we measured Δχ(do) as well as the susceptibility(More)
PURPOSE To investigate whether intravitreally injected peanut agglutinin (PNA) conjugated with a fluorochrome can specifically label retinal cones in vivo and to evaluate its clinical potential. METHODS Fluorescein- or rhodamine-conjugated PNA (0.005%-0.5%) was intravitreally injected into anesthetized mouse, guinea pig, or monkey and retinas were removed(More)
Measuring venous oxygen saturation (HbO2) in large blood vessels can provide important information about oxygen delivery and its consumption in vital organs. Quantification of blood's T2 value via MR can be utilized to determine HbO2 noninvasively. We propose a fast method for in vivo blood T2 quantification via computing the complex difference of(More)
PURPOSE To evaluate the longitudinal repeatability and accuracy of cerebral blood flow (CBF) measurements by using pseudo-continuous arterial spin-labeled (pCASL) perfusion magnetic resonance (MR) imaging in typically developing children. MATERIALS AND METHODS Institutional review board approval with HIPAA compliance and informed consent were obtained.(More)
INTRODUCTION Astronauts face transient disruptions of sensorimotor functions after spaceflight. Computerized dynamic posturography (CDP) testing has been used to document functional recovery; however, its objective value in return-to-duty decision-making has not been established. Therefore, we studied the diagnostic accuracy of CDP to determine the most(More)
Photoreceptor degeneration is followed by significant morphological changes in the second-order retinal neurons in humans and in several genetic animal models. However, it is not clear whether similar changes occur when photoreceptor degeneration is induced nongenetically, raising the question whether these changes are a general effect of deafferentation(More)