Maps of optical differential pathlength factor of human adult forehead, somatosensory motor and occipital regions at multi-wavelengths in NIR

Abstract

The optical differential pathlength factor (DPF) is an important parameter for physiological measurement using near infrared spectroscopy, but for the human adult head it has been available only for the forehead. Here we report measured DPF results for the forehead, somatosensory motor and occipital regions from measurements on 11 adult volunteers using a time-resolved optical imaging system. The optode separation was about 30 mm and the wavelengths used were 759 nm, 799 nm and 834 nm. Measured DPFs were 7.25 for the central forehead and 6.25 for the temple region at 799 nm. For the central somatosensory and occipital areas (10 mm above the inion), DPFs at 799 nm are 7.5 and 8.75, respectively. Less than 10% decreases of DPF for all these regions were observed when the wavelength increased from 759 nm to 834 nm. To compare these DPF maps with the anatomical structure of the head, a Monte Carlo simulation was carried out to calculate DPF for these regions by using a two-layered semi-infinite model and assuming the thickness of the upper layer to be the sum of the thicknesses of scalp and skull, which was measured from MRI images of a subject's head. The DPF data will be useful for quantitative monitoring of the haemodynamic changes occurring in adult heads.

Motor imagery in response to fake feedback measured by functional near-infrared spectroscopy

“…Based on the raw data, the given geometry of the sensor, and the application of the modified Beer-Lambert law, concentration changes of O 2 Hb and HHb were calculated (Haensse, et al 2005). The differential path length factor (DPF) was set to 7.5, 7.25 and 7.0 at 750nm, 800nm and 875nm (Zhao, et al 2002).…”

Wireless miniaturized in-vivo near infrared imaging

“…For the arterial occlusion experiment described hereafter, the DPF values published in [6] were interpolated according to the DPF as a function of wavelength published in [5]: we used 4.48 for 760 nm and 3.81 for 870 nm. For the reconstruction of the cortical hemodynamic signals a DPF of 7.75 for 760 nm and 7.25 for 870 nm was chosen [7]. The absorption coefficients for the O 2 Hb and HHb were taken from [8].…”

Assessment of Potential Short-Term Effects of Intermittent UMTS Electromagnetic Fields on Blood Circulation in an Exploratory Study, Using Near-Infrared Imaging

“…Δ[O2Hb] and Δ[HHb] were calculated using the modified Lambert-Beer law. The differential pathlength factors (DPF) for C3 given in the literature [8] were linearly interpolated to DPF690 nm= 8.21 and DPF830 nm = 7.3 and used in the modified Lambert-Beer law.…”