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Human cortical perfusion and the arterial pulse: a near-infrared spectroscopy study.

Kwan HC, Cheng A, Liu R, Borrett DS - BMC Physiol. (2004)

Bottom Line: The arterial pulse pattern was extracted from the left middle finger by means of plethesmographic techniques.Cross-correlation analysis was performed to provide evidence for a causal relation between the arterial pulse and relative changes in cortical total hemoglobin.In addition, the determination of the statistical significance of this relation was established by the use of phase-randomized surrogates.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology Medical Sciences Building, Room 3232, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8 Canada. h.kwan@utoronto.ca

ABSTRACT

Background: The pulsatile nature of the arterial pulse induces a pulsatile perfusion pattern which can be observed in human cerebral cortex with non-invasive near-infrared spectroscopy. The present study attempts to establish a quantitative relation between these two events, even in situations of very weak signal-to-noise ratio in the cortical perfusion signal. The arterial pulse pattern was extracted from the left middle finger by means of plethesmographic techniques. Changes in cortical perfusion were detected with a continuous-wave reflectance spectrophotometer on the scalp overlying the left prefrontal cortex. Cross-correlation analysis was performed to provide evidence for a causal relation between the arterial pulse and relative changes in cortical total hemoglobin. In addition, the determination of the statistical significance of this relation was established by the use of phase-randomized surrogates.

Results: The results showed statistically significant cross correlation between the arterial and perfusion signals.

Conclusions: The approach designed in the present study can be utilized for a quantitative and continuous assessment of the perfusion states of the cerebral cortex in experimental and clinical settings even in situations of extremely low signal-to-noise ratio.

Show MeSH
Power spectrum of change in total hemoglobin (upper trace of Figure 1). Power in arbitrary units.
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Figure 3: Power spectrum of change in total hemoglobin (upper trace of Figure 1). Power in arbitrary units.

Mentions: A stretch of 8 second raw data is shown in Figure 1 from one subject. The upper trace shows the optical signal representing changes in total hemoglobin in the prefrontal cortex, and the corresponding arterial pulse signals recorded at the left middle finger is shown below. Note that in this experimental setting, there is no evident oscillatory response in the optical data at the cortical level associated with each of the arterial pulses. This indicates that the response was weak, a conclusion corroborated by a weak Fourier component at the heart rate frequencies observed in the optical signal (Figure 3).


Human cortical perfusion and the arterial pulse: a near-infrared spectroscopy study.

Kwan HC, Cheng A, Liu R, Borrett DS - BMC Physiol. (2004)

Power spectrum of change in total hemoglobin (upper trace of Figure 1). Power in arbitrary units.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC411046&req=5

Figure 3: Power spectrum of change in total hemoglobin (upper trace of Figure 1). Power in arbitrary units.
Mentions: A stretch of 8 second raw data is shown in Figure 1 from one subject. The upper trace shows the optical signal representing changes in total hemoglobin in the prefrontal cortex, and the corresponding arterial pulse signals recorded at the left middle finger is shown below. Note that in this experimental setting, there is no evident oscillatory response in the optical data at the cortical level associated with each of the arterial pulses. This indicates that the response was weak, a conclusion corroborated by a weak Fourier component at the heart rate frequencies observed in the optical signal (Figure 3).

Bottom Line: The arterial pulse pattern was extracted from the left middle finger by means of plethesmographic techniques.Cross-correlation analysis was performed to provide evidence for a causal relation between the arterial pulse and relative changes in cortical total hemoglobin.In addition, the determination of the statistical significance of this relation was established by the use of phase-randomized surrogates.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology Medical Sciences Building, Room 3232, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8 Canada. h.kwan@utoronto.ca

ABSTRACT

Background: The pulsatile nature of the arterial pulse induces a pulsatile perfusion pattern which can be observed in human cerebral cortex with non-invasive near-infrared spectroscopy. The present study attempts to establish a quantitative relation between these two events, even in situations of very weak signal-to-noise ratio in the cortical perfusion signal. The arterial pulse pattern was extracted from the left middle finger by means of plethesmographic techniques. Changes in cortical perfusion were detected with a continuous-wave reflectance spectrophotometer on the scalp overlying the left prefrontal cortex. Cross-correlation analysis was performed to provide evidence for a causal relation between the arterial pulse and relative changes in cortical total hemoglobin. In addition, the determination of the statistical significance of this relation was established by the use of phase-randomized surrogates.

Results: The results showed statistically significant cross correlation between the arterial and perfusion signals.

Conclusions: The approach designed in the present study can be utilized for a quantitative and continuous assessment of the perfusion states of the cerebral cortex in experimental and clinical settings even in situations of extremely low signal-to-noise ratio.

Show MeSH