Parameters of the experimental setup of blood pulsations imaging.

<p>Parameters of the experimental setup of blood pulsations imaging.</p

Spatial distributions of the blood pulsation amplitude (odd rows) and the relative phase of pulsations (even rows) calculated for four subjects (A–D) at sequential moments before occlusion of blood vessels.

<p>In the left corner of each map there is indicated the starting moment (in seconds) after which these maps are calculated for each cardiac cycle. The color scales on the right show the BPA (upper, in arbitrarily units) and the relative phase (lower, in degrees). White circles on phase maps show positions of asynchronous spots.</p

Time traces of the BPA (black curves) and the mean intensity of the back-reflected light (blue curves) calculated for four subjects by data averaging within selected ROI of 8×8 pixels.

<p>We placed the ROI in the ‘hot’ spots of 2D maps of the blood pulsation amplitude which are shown in the middle of each row. Yellow arrows indicate the ROI positions (which are shown in the BPA maps with the black squares) within which the respective graphs were calculated. Moments of blood vessels occlusion and its release are shown in every graph by red arrows.</p

Time traces of raw PPG signal within the palm area.

<p>(A) An example of the signal during the complete occlusion test (about 12 min). (B) Zoomed part of the signal (blue line) with the temporal boundaries of each cardiac cycle (shown by red circles), which has been approximated to the harmonic reference signal (red dotted line). The black line in the part (B) is the raw PPG signal filtered by continuous averaging of the data over 30 frames.</p

Estimation of the signal-to-noise ratio.

<p>(A) An example of 2D map of the blood pulsation amplitude for subject's arm and the cardboard; (B) Time-traces of the BPA averaged within 15×15 pixels regions shown by black rectangles in (A): the blue line for the arm and the green line for the cardboard; (C – F) Time-averaged BPA from randomly chosen regions within white rectangles sizing 30×30 (C), 15×15 (D), 8×8 (E) pixels, and for single pixel (F).</p

Simplified layout of the experiment.

<p>Video of subject’s palm and electrocardiogram were simultaneously recorded. Green illumination of the palm was switched to the NIR and vice versa in a frame-to-frame regime.</p

Spatial and amplitude correlation of changes induced by the skin-glass contact at green and NIR illumination.

<p>(a) The shift between the centers of the “hot” spots in the amplitude maps found at green and NIR illumination for all studied subjects. (b) Scatter plot of the PPG-amplitude increase due to the contact calculated at green and NIR illumination.</p

Influence of the skin-glass contact on the PPG amplitude measured at green and NIR wavelengths.

<p>(a) Average PPG amplitude measured in “hot” spots in the contact experiment (Gl) and in respective spots in the contactless experiment (NC). Here Gr and NIR stand for green (525 nm) and NIR (810 nm) illumination, respectively. (b) Ratio of the mean amplitude measured in the glass-contact to that in the contactless experiment for both wavelengths. The individual measurements are shown by circles, whereas the bars represent mean values for the whole data sets.</p

Asynchronicity of Facial Blood Perfusion in Migraine

<div><p>Asymmetrical changes in blood perfusion and asynchronous blood supply to head tissues likely contribute to migraine pathophysiology. Imaging was widely used in order to understand hemodynamic variations in migraine. However, mapping of blood pulsations in the face of migraineurs has not been performed so far. We used the Blood Pulsation Imaging (BPI) technique, which was recently developed in our group, to establish whether 2D-imaging of blood pulsations parameters can reveal new biomarkers of migraine. BPI characteristics were measured in migraineurs during the attack-free interval and compared to healthy subjects with and without a family history of migraine. We found a novel phenomenon of transverse waves of facial blood perfusion in migraineurs in contrast to healthy subjects who showed synchronous blood delivery to both sides of the face. Moreover, the amplitude of blood pulsations was symmetrically distributed over the face of healthy subjects, but asymmetrically in migraineurs and subjects with a family history of migraine. In the migraine patients we found a remarkable correlation between the side of unilateral headache and the direction of the blood perfusion wave. Our data suggest that migraine is associated with lateralization of blood perfusion and asynchronous blood pulsations in the facial area, which could be due to essential dysfunction of the autonomic vascular control in the face. These findings may further enhance our understanding of migraine pathophysiology and suggest new easily available biomarkers of this pathology.</p></div

Examples of the images obtained with the BPI system and with the thermographic camera: (A) 2D distribution of the blood pulsation amplitude; (B) 2D map of the blood pulsation phase; (C) 2D distribution of the skin temperature.

<p>Examples of the images obtained with the BPI system and with the thermographic camera: (A) 2D distribution of the blood pulsation amplitude; (B) 2D map of the blood pulsation phase; (C) 2D distribution of the skin temperature.</p