Optical measurement of cerebral hemodynamics and oxygen metabolism in neonates with congenital heart defects

Abstract

Abstract. We employ a hybrid diffuse correlation spectroscopy ͑DCS͒ and near-infrared spectroscopy ͑NIRS͒ monitor for neonates with congenital heart disease ͑n =33͒. The NIRS-DCS device measured changes during hypercapnia of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations; cerebral blood flow ͑rCBF DCS ͒; and oxygen metabolism ͑rCMRO 2 ͒. Concurrent measurements with arterial spin-labeled magnetic resonance imaging ͑rCBF ASL-MRI , n =12͒ cross-validate rCBF DCS against rCBF ASL-MRI , showing good agreement ͑R = 0.7, p = 0.01͒. The study demonstrates use of NIRS-DCS on a critically ill neonatal population, and the results indicate that the optical technology is a promising clinical method for monitoring this population.

Cerebral Oxygen Metabolism in Neonatal Hypoxic Ischemic Encephalopathy during and after Therapeutic Hypothermia

“…Here the subscript 'i' in CMRO 2i is used to acknowledge that CMRO 2 is derived using a CBF index (CBF i ), which although a flux (in mm 2 /second), correlates well with other measures of cerebral perfusion (in ml/100 g per minute). In fact, DCS CBF i correlates well with MR arterial spin labeling 38 and with phase-encoded velocity mapping (VENC) MRI measures of relative blood flow in the jugular veins and superior vena cava in neonates/children with congenital heart defect. 39 Further support for the use of DCS CBF i measures was provided by the high correlation (r 2 ¼ 0.73, Po0.01) between relative CBF i and Xenon CT cerebral blood perfusion measures in critically brain-injured adults.…”

Cerebral Oxygen Metabolism in Neonates with Congenital Heart Disease Quantified by MRI and Optics

“…This observation agrees with our previous experience in healthy adults 20 and with several other publications that examined cerebrovascular reactivity to hypercapnia in patients with congenital heart defects using localized measurement techniques, such as DOS and DCS. 15,24,38 In addition to generating new physiologic data, this work also achieved several technical goals. First, it demonstrates the feasibility of a combined MRI-susceptometry and phase-contrast method to measure S v O 2 , CBF and CMRO 2, in neonates with complex CHD, all in absolute physiologic units.…”

“…The study protocol has been described previously 15,16 and the timeline is illustrated in Figure 1. Briefly, once the anesthetized and paralyzed patient was stabilized and baseline DOS measurements were made while obtaining vascular access, patients were brought to the MRI scanner where a second MRI-compatible, noninvasive optical probe was placed on the forehead for continuous DOS/ DCS monitoring.…”

“…These techniques are described in Durduran et al 21 and the specific protocol and measurement details for the present study is detailed in references 15,16 and in Appendix 1. In brief, frequency-domain DOS enables quantification of absolute regional (microvascular) cerebral oxy-and deoxy-hemoglobin concentration (HbO 2 and HbR, respectively, in mmol/L) using photon diffusion theory 21 From this information, total Hb concentra-…”

“…Previous studies have shown that changes of BFI relative to a baseline are strongly correlated with changes in CBF relative to baseline values measured by other CBF techniques. 15,21,24 Diffuse Optical Spectroscopy and Diffuse Correlation Spectroscopy Instrumentation and Study Protocol A schematic of the measurement protocol is provided in Figure 1, and further details are given in Appendix 1. First, baseline DOS measurements of absolute tissue physiologic parameters, i.e., HbR, HbO 2 , THC, and StO 2 were made on the patient's forehead while the subject was sedated, stabilized, and while vascular access was obtained outside the MRI scanner.…”