Spectral analysis of near-infrared spectroscopy signals measured from prefrontal lobe in subjects at risk for stroke

• Published in: Medical physics (Lancaster) Vol. 39; no. 4; pp. 2179 - 2185
• Main Authors: Li, Zengyong, Zhang, Ming, Xin, Qing, Chen, Guoqiang, Liu, Feifei, Li, Jianping
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.04.2012
• Subjects: Algorithms; arterial stiffness; biomechanics; biomedical optical imaging; blood vessels; brain; cerebral oxygenation; Diagnosis, Computer-Assisted - methods; Digital computing or data processing equipment or methods, specially adapted for specific applications; diseases; elastic constants; Elastic properties; Female; Haemodynamics; Heart; Hemoglobins - analysis; Humans; Infrared; Infrared spectrometers, auxiliary equipment, and techniques; infrared spectroscopy; Male; medical signal processing; Middle Aged; Muscles; near-infrared spectroscopy; Optical imaging of neuronal activity; oscillations; Oscillations and resonance; Prefrontal Cortex - metabolism; Reproducibility of Results; Risk Assessment; Risk Factors; Sensitivity and Specificity; spectral analysis; Spectrometry; Spectrophotometry; Monochromators; Measuring colours; Spectroscopy, Near-Infrared - methods; Spectrum analysis; spontaneous oscillation; Stroke; Stroke - blood; Stroke - diagnosis; Tissues; Vascular system; Velocity measurement; wavelet transform; wavelet transforms; Wavelets; arterial stiffness; near-infrared spectroscopy; spontaneous oscillation; wavelet transform; cerebral oxygenation
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.3696363

Purpose: The objective of this study was to assess the spontaneous cerebral oscillations based on the wavelet transform of near-infrared spectroscopy (NIRS) signals in subjects at risk for atherosclerotic stroke. Methods: A total of 32 subjects were recruited from the university to participate in this study: 20 were normal subjects (age = 59.6 ± 10.2 year) and the other 12 were subjects at risk for ischemic stroke (age = 60.2 ± 10.1 year).The cerebral oxygenation signal was monitored for 10 min from the left prefrontal lobe using NIRS. Results: With spectral analysis based on wavelet transform, five frequency intervals were identified (I, 0.005–0.02 Hz; II, 0.02–0.06 Hz; III, 0.06–0.15 Hz; IV, 0.15–0.40 Hz; and V, 0.40–2.0 Hz). The amplitude of the [Hb] in the frequency intervals from I to V and of the [HbO2] in frequency intervals I and V in subjects at risk for stroke were found to be significantly lower compared to the amplitudes in normal subjects. Conclusions: The reduction of spontaneous oscillations in these subjects suggests an increased stiffness in the cerebral artery. This indicates the possibility of applying spontaneous oscillations, based on the wavelet transform of NIRS signals, to assess the risk in subjects with atherosclerosis.