Medical video recording

Kymography is a technique of function imaging of vocal folds using registered glottal cycle over a period of time, at any cross-section of the folds.

Kymography requires proper conduct it in a precise way and steps must be performed in the correct order. The diagram of the kymographic imaging registration is presented below, thanks to which the kymographic cross-section will give a complete picture of the function of the vocal folds in time and will allow for a complete analysis about the condition of the voice organ.

Figure 1 shows a schematic time analysis of the cropped images. Kymography begins with framing the videostroboscopic recording on the basis of images selected by the user recorded in different positions of the vocal folds (i.e. the moments of the positions of the vocal folds). Corresponding rectangular areas containing the entire vocal folds are (for three exemplary positions) marked in yellow at the top of the drawing.

After the cropping stage is completed, we get (red arrows) rotated and magnified images of the vocal folds for all frames from the source video - shown on the left in the figure (for three sample positions). After the framing stage is completed, we get (red arrows) rotated and magnified images of the vocal folds for all frames from the source video - shown on the left in the figure (for three sample positions).

From the created frames, sections through the vocal folds are selected at a predetermined place in successive positions, i.e. a predetermined horizontal line from each frame. These lines are used to compose the time section (time analysis of the folds operation on the selected section) - as shown by the orange arrows for the three exemplary positions. Using the slider on the timeline, it is possible to set the selected moment of the recording time, on the left side the full cropped frame from this position is automatically previewed.

Fig. 1 The slider on the cropped frame allows you to select the place of the cross-section that is to be analyzed (i.e. the selection of the appropriate horizontal line of the image), as shown in Fig. 2. Changing the position of the slider up or down automatically determines the appropriate time section and displays it on the right parts of the window. On the right side of the diagram, the time sections obtained for three, for example, selected locations on the vocal folds are shown.

Kymographic imaging allows you to perfectly define the occurrence and place of regurgitation of the vocal folds or irregular functionality. These are conditions that particularly affect groups of people who work with their voices, such as singers and teachers. The use of a kymographic cross-section to diagnose the function of the vocal folds allows for clear and unambiguous information about the condition of the voice organ. An example of the use of kymography to determine the regurgitation of folds and the place of its occurrence (the cross-section in which it occurs) is presented in the diagram below.

Fig. 2. Scheme of selection of the analyzed site of the cross-section

In the temporal view shown in Figure 2 at the top right, regurgitation of the vocal folds is very clearly visible: along the entire length of the temporal section, i.e. in the entire time range of the folds analyzed, there is a gap between the left and right folds. The other two sections, made for other places on the vocal folds, do not show regurgitation - the phases of closings and openings are visible. By setting the appropriate cross-section and location with the use of sliders, you can very precisely visualize the degree of regurgitation and determine the place on the folds where it occurs. Other abnormalities in the work of the vocal folds, e.g. asymmetry, can be examined similarly.

Kymography significantly exceeds the amount of information that can be obtained from a single frame recorded using strobe camera. The study of unevenness of the function of the vocal folds using the kymographic method is at least comparable with the acoustic analysis in terms of the ease of documentation and the amount of information contained in a single kymographic image.