Medical video recording

After correctly recording the video sequence and selecting the appropriate fragment from it, the next step of the analysis is cropping. Cropping involves cutting, aligning (if necessary - rotating) and enlarging the area containing the vocal folds (Fig. 1). To this end, the ends of the vocal folds (i.e. the front and back ends of the glottis fissure) are marked on the image with the ends of the segment. The selected points are then automatically tracked thanks to the intelligent algorithms used in the DiagnoScope Specialist program, which significantly improves the quality of the obtained kymographic cross-section and significantly reduces the labor consumption of the analysis.

Fig. 1. Recording imaging the function of the vocal folds; at the top: original video recorded from endoscope; at the bottom: the same video but properly cropped

If the selected fragment of the video sequence contains one short circuit and one fold opening, the ends of the vocal folds in three operating phases should be marked, i.e. at the largest opening, the smallest short circuit and in the instant between these two boundary phases.

Between the times when the user has marked the exact positions of the ends of the vocal cords, the program approximates the movement of the ends of the vocal cords and searches for their actual location near the expected location. Therefore, it should be noted that in the time intervals between the marked positions of the folds there should be no large changes in the direction of movement of the marked points. If there is a large change in the direction of movement, in particular a turn in the opposite direction, then it is advantageous to additionally mark the extreme position of the point to facilitate automatic tracking of the selected points and to enable a quick analysis.

In order to obtain an accurate time course of the function of the vocal folds, it is necessary to correctly select the appropriate points to be tracked by the program, and mark them at appropriate times, which requires the user to gain some experience in cropping video sequences.

Cropping a video recording is a very important function of the DiagnoScope Specialist. Image stabilization greatly helps to obtain the correct and, above all, clear results of the kymographic cross-section of the function of the vocal folds.

The lack of cropping results in a very illegible result, which makes it practically impossible to conduct a full analysis. Examples of kymography made with the use of standard software and the DiagnoScope Specialist program are shown in Fig. 2.

Fig. 2. At the top: Kymographic cross-section of the function of the vocal folds obtained using standard software; at the bottom: kymographic cross-section obtained from the same source recording using the DiagnoScope Specialist program with correct cropping

A properly cropped video sequence gives a full picture of the workflow of the vocal folds in time and allows for a complete diagnosis of abnormalities in the function of the vocal folds. In comparison with the upper image in Fig. 2, the function of the vocal folds as a function of time (the image made with the DiagnoScope Specialist program) is visualized in a very legible way, the kymographic cross-section is arranged along a straight line.

After making the correct video recording and its cropping, it can be said that we received a video recording prepared for the kymographic analysis, i.e. to study the function of the vocal folds in time, which we receive as a result. We invite you to view sample images of kymography made with the DiagnoScope Specialist program.