Mapping of calf muscle oxygenation and haemoglobin content during dynamic plantar flexion exercise by multi-channel time-resolved near-infrared spectroscopy.
A compact and fast multi-channel time-resolved near-infrared spectroscopy system for tissue oximetry was developed. It employs semiconductor laser and fibre optics for delivery of optical signals. Photons are collected by eight 1 mm fibres and detected by a multianode photomultiplier. A time-correlated single photon counting board is used for the parallel acquisition of time-resolved reflectance curves. Estimate of the reduced scattering coefficient is achieved by fitting with a standard model of diffusion theory, while the modified Lambert-Beer law is used to assess the absorption coefficient. In vivo measurements were performed on five healthy volunteers to monitor spatial changes in calf muscle (medial and lateral gastrocnemius; MG, LG) oxygen saturation (SmO2) and total haemoglobin concentration (tHb) during dynamic plantar flexion exercise performed at 50% of the maximal voluntary contraction. At rest SmO2 was 73.0 +/- 0.9 and 70.5 +/- 1.7% in MG and LG, respectively (P = 0.045). At the end of the exercise, SmO2 decreased (69.1 +/- 1.8 and 63.8 +/- 2.1% in MG and LG, respectively; P < 0.01). The LG desaturation was greater than the MG desaturation (P < 0.02). These results strengthen the role of time-resolved near-infrared spectroscopy as a powerful tool for investigating the spatial and temporal features of muscle SmO2 and tHb.
Torricelli
Alessandro
A
INFM-Dipartimento di Fisica and IFN-CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, 1-20133 Milan, Italy.
Quaresima
Valentina
V
Pifferi
Antonio
A
Biscotti
Giovanni
G
Spinelli
Lorenzo
L
Taroni
Paola
P
Ferrari
Marco
M
Cubeddu
Rinaldo
R
D000273:Adipose Tissue; D000328:Adult; D015444:Exercise; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D019047:Phantoms, Imaging; D017785:Photons; D013053:Spectrophotometry; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013997:Time Factors
D006454:Hemoglobins; D010100:Oxygen