Phase Analysis of Low Frequency Hemodynamic Oscillations in Near Infrared Spectroscopy.
Zheng, Feng.
2011
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Abstract: To study low
frequency oscillations (around 0.1 Hz) of tissue, oxy-hemoglobin and deoxy-hemoglobin
concentrations measured by near-infrared spectroscopy, we proposed two phase analysis
methods: one is a cross-correlation phasor method, and another is a phase
synchronization analysis method. Both methods yield similar results and provide a
straightforward visualization of the phase ... read morerelationships between deoxy- and
oxy-hemoglobin concentrations with the help of circular statistics. We argued that
measured oscillations of deoxy- and oxy-hemoglobin with an intermediate phase difference
which is neither 0 nor pi; may results from the interplay of different physiological
processes that are out-of-phase with respect to each other. We observed that in most
cases under the Watson-Williams statistical test, there is a change in the phase
difference between deoxy- and oxy-hemoglobin from rest conditions to mental workloads.
The change in standard deviation of the phase distribution may be connected with the
change in regulation of physiological processes in human cerebral cortex. The analytical
tools we developed from phasor concepts, such as phase-sector (to display the phase
distribution) and TARGET map (to display the temporal evolution of the phase), can be
powerful tools for dynamic monitoring and physiological assessment. The phase methods in
this thesis would provide novel opportunities for understanding cerebral autoregulation,
functional connectivity networks and physiological processes underlying the measured
near-infrared signals.
Thesis (M.S.)--Tufts University, 2011.
Submitted to the Dept. of Biomedical Engineering.
Advisor: Sergio Fantini.
Committee: Fiorenzo Omenetto, and Robert Jacob.
Keywords: Biomedical Engineering, and Computer Science.read less - ID:
- 0k225p115
- Component ID:
- tufts:21071
- To Cite:
- TARC Citation Guide EndNote
