Regional heterogeneity of cerebral hemodynamics in mild neonatal encephalopathy measured with multichannel near-infrared spectroscopy

Wavelet-based neurovascular coupling can predict brain abnormalities in neonatal encephalopathy

“…We used a MATLAB-based software package and analytic Morlet wavelet to perform WTC analysis ( Grinsted et al, 2004 ) between the spontaneous oscillations of artifact-free NIRS-SctO2 and aEEG signals in neonates with encephalopathy, as reported in our recent publications ( Das et al, 2020 , Tian et al, 2016 , Tian, 2020 ). WTC is a time–frequency domain analysis and characterizes the squared cross-wavelet coherence, R 2 , and relative phase, Δ ϕ , between two time series at multiple time scales and over the entire time duration, without a prior assumption of linearity and stationarity.…”

“…All the pixels which have statistically significant coherence values are marked as black contours within the time-scale map. Using a time-scale (equivalent to time–frequency) domain, NVC was assessed by percentage of the number of significant pixels ( Pix sig ) over the number of total pixels ( Pix total ) within the given time-scale map ( Das et al, 2020 , Tian et al, 2016 , Tian, 2020 ), namely, Pix sig / Pix total . Specifically, Pix sig and Pix total were quantified by summing pixel numbers across all wavelet time scales only within the identified contours and all scales respectively.…”

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

“…In neonates with CHD, equipoise is likely lost for clinical studies of NIRS since it is already widely used in these patients in cardiac intensive care units and its benefit in that population has been demonstrated in small studies. Clinical trials of NIRS and time-synchronized analytical tools are being studied in other populations, however, such as neonates with HIE ( 64 , 65 , 168 ) and those born preterm ( 121 , 122 , 169 ).…”

Optimal neuromonitoring techniques in neonates with hypoxic ischemic encephalopathy

“…Various measures of autoregulation using NIRS have included a higher pressure passivity index with increased coherence between mean arterial pressure and cerebral oxygen saturation, increased time domain reactivity index, and wavelet coherence analysis ( 53 – 55 ). Regionality of impaired autoregulation has also been described, with greatest differences in anterior compared to posterior measures ( 56 ). These findings suggest that temporal-occipital regions may potentially be more vulnerable to autoregulatory impairment given higher baseline perfusion and metabolism in these areas in the newborn.…”