Observing temperature fluctuations in humans using infrared imaging

In this work we demonstrate that functional infrared imaging is capable of detecting low frequency temperature fluctuations in intact human skin and revealing spatial, temporal, spectral, and time-frequency based differences among three tissue classes: microvasculature, large sub-cutaneous veins, and the remaining surrounding tissue of the forearm. We found that large veins have stronger contractility in the range of 0.005-0.06 Hz compared to the other two tissue classes. Wavelet phase coherence and power spectrum correlation analysis show that microvasculature and skin areas without vessels visible by IR have high phase coherence in the lowest three frequency ranges (0.005-0.0095 Hz, 0.0095-0.02 Hz, and 0.02-0.06 Hz), whereas large veins oscillate independently.

[1]  C. Torrence,et al.  A Practical Guide to Wavelet Analysis. , 1998 .

[2]  M. Kendall.  Rank Correlation Methods , 1949 .

[3]  Conrad Kufta,et al.  Intraoperative infrared functional imaging of human brain , 2003, Annals of neurology.

[4]  A. Stefanovska,et al.  Low-frequency oscillations of the laser Doppler perfusion signal in human skin. , 2006, Microvascular research.

[5]  G. Vainer,et al.  Heterogeneous thermograms: the methods of attack , 2007 .

[6]  José M. Bioucas-Dias,et al.  Estimation of signal subspace on hyperspectral data , 2005, SPIE Remote Sensing.

[7]  Frank Klawonn,et al.  Fuzzy Clustering of Short Time-Series and Unevenly Distributed Sampling Points , 2003, IDA.

[8]  Karl J. Friston,et al.  Human Brain Function , 1997 .

[9]  J. MacQueen.  Some methods for classification and analysis of multivariate observations , 1967 .

[10]  Alan Bernjak,et al.  Wavelet Phase Coherence Analysis: Application to Skin Temperature and Blood Flow , 2004 .

[11]  J. Boardman,et al.  Discrimination among semi-arid landscape endmembers using the Spectral Angle Mapper (SAM) algorithm , 1992 .

[12]  T. Warren Liao,et al.  Clustering of time series data - a survey , 2005, Pattern Recognit..

[13]  Chein-I Chang,et al.  An information-theoretic approach to spectral variability, similarity, and discrimination for hyperspectral image analysis , 2000, IEEE Trans. Inf. Theory.

[14]  M. Kendall,et al.  Rank Correlation Methods , 1949 .

[15]  James McNames,et al.  A Biomedical Signal Processing Toolbox , 2002 .

[16]  A. Stefanovska,et al.  Low-frequency blood flow oscillations in congestive heart failure and after β1-blockade treatment , 2008, Microvascular research.

[17]  Paul Wintz,et al.  Digital image processing (2nd ed.) , 1987 .