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author:("Yu, guoyang")
1.  Direct measurement of tissue blood flow and metabolism with diffuse optics 
Diffuse optics has proven useful for quantitative assessment of tissue oxy- and deoxyhaemoglobin concentrations and, more recently, for measurement of microvascular blood flow. In this paper, we focus on the flow monitoring technique: diffuse correlation spectroscopy (DCS). Representative clinical and pre-clinical studies from our laboratory illustrate the potential of DCS. Validation of DCS blood flow indices in human brain and muscle is presented. Comparison of DCS with arterial spin-labelled MRI, xenon-CT and Doppler ultrasound shows good agreement (0.50
doi:10.1098/rsta.2011.0232
PMCID: PMC3263785  PMID: 22006897
diffuse correlation spectroscopy; blood flow; cerebral blood flow; oxygen metabolism; brain; cancer
Journal of biomedical optics  2009;14(3):034015.
We used a nonimpact inertial rotational model of a closed head injury in neonatal piglets to simulate the conditions following traumatic brain injury in infants. Diffuse optical techniques, including diffuse reflectance spectroscopy and diffuse correlation spectroscopy (DCS), were used to measure cerebral blood oxygenation and blood flow continuously and noninvasively before injury and up to 6 h after the injury. The DCS measurements of relative cerebral blood flow were validated against the fluorescent microsphere method. A strong linear correlation was observed between the two techniques (R = 0.89, p < 0.00001). Injury-induced cerebral hemodynamic changes were quantified, and significant changes were found in oxy- and deoxy-hemoglobin concentrations, total hemoglobin concentration, blood oxygen saturation, and cerebral blood flow after the injury. The diffuse optical measurements were robust and also correlated well with recordings of vital physiological parameters over the 6-h monitoring period, such as mean arterial blood pressure, arterial oxygen saturation, and heart rate. Finally, the diffuse optical techniques demonstrated sensitivity to dynamic physiological events, such as apnea, cardiac arrest, and hypertonic saline infusion. In total, the investigation corraborates potential of the optical methods for bedside monitoring of pediatric and adult human patients in the neurointensive care unit.
doi:10.1117/1.3146814
PMCID: PMC3169814  PMID: 19566308
diffuse correlation spectroscopy (DCS); diffuse reflectance spectroscopy (DRS); cerebral hemodynamics; cerebral blood flow; traumatic brain injury; near—infrared spectroscopy (NIRS)
Neurocritical care  2010;12(2):173-180.
Background
This study assesses the utility of a hybrid optical instrument for noninvasive transcranial monitoring in the neurointensive care unit. The instrument is based on diffuse correlation spectroscopy (DCS) for measurement of cerebral blood flow (CBF), and near-infrared spectroscopy (NIRS) for measurement of oxy- and deoxy-hemoglobin concentration. DCS/NIRS measurements of CBF and oxygenation from frontal lobes are compared with concurrent xenon-enhanced computed tomography (XeCT) in patients during induced blood pressure changes and carbon dioxide arterial partial pressure variation.
Methods
Seven neurocritical care patients were included in the study. Relative CBF measured by DCS (rCBFDCS), and changes in oxy-hemoglobin (ΔHbO2), deoxy-hemoglobin (ΔHb), and total hemoglobin concentration (ΔTHC), measured by NIRS, were continuously monitored throughout XeCT during a baseline scan and a scan after intervention. CBF from XeCT regions-of-interest (ROIs) under the optical probes were used to calculate relative XeCT CBF (rCBFXeCT) and were then compared to rCBFDCS. Spearman’s rank coefficients were employed to test for associations between rCBFDCS and rCBFXeCT, as well as between rCBF from both modalities and NIRS parameters.
Results
rCBFDCS and rCBFXeCT showed good correlation (rs = 0.73, P = 0.010) across the patient cohort. Moderate correlations between rCBFDCS and ΔHbO2/ΔTHC were also observed. Both NIRS and DCS distinguished the effects of xenon inhalation on CBF, which varied among the patients.
Conclusions
DCS measurements of CBF and NIRS measurements of tissue blood oxygenation were successfully obtained in neurocritical care patients. The potential for DCS to provide continuous, noninvasive bedside monitoring for the purpose of CBF management and individualized care is demonstrated.
doi:10.1007/s12028-009-9305-x
PMCID: PMC2844468  PMID: 19908166
Near-infrared spectroscopy; Diffuse correlation spectroscopy; Cerebral blood flow; Xenon CT; Neurocritical care
Optics express  2009;17(15):12571-12581.
Four very low birth weight, very premature infants were monitored during a 12° postural elevation using diffuse correlation spectroscopy (DCS) to measure microvascular cerebral blood flow (CBF) and transcranial Doppler ultrasound (TCD) to measure macrovascular blood flow velocity in the middle cerebral artery. DCS data correlated significantly with peak systolic, end diastolic, and mean velocities measured by TCD (pA =0.036, 0.036, 0.047). Moreover, population averaged TCD and DCS data yielded no significant hemodynamic response to this postural change (p>0.05). We thus demonstrate feasibility of DCS in this population, we show correlation between absolute measures of blood flow from DCS and blood flow velocity from TCD, and we do not detect significant changes in CBF associated with a small postural change (12°) in these patients.
PMCID: PMC2723781  PMID: 19654660

Results 1-4 (4)