Computerized Image Processing in Swallowing Analysis

One valuable diagnostic tool for the evaluation of patients with swallowing disorders is fluoroscopic imaging. Traditionally, the modified barium swallow procedure has been the preferred method utilized in the diagnosis of dysphagia. This method has allowed for the direct observation of many different types of swallowing problems such as delays in oral and pharyngeal transit time, delays in pharyngeal response time, and aspiration. This paper presents a protocol outlining the use of a computer software program to aid in the videofluorographic analysis of the modified barium swallow procedure and the calculation of transit times.

Frame by frame videofluorographic analysis often focuses on temporal measurements of bolus movement, and the coordination and movement of oropharyngeal structures during a swallow. These measurements are then compared to the temporal measurements of a normal swallow. The timing information that has been recorded on each frame creates a reference point for the occurrence of specific events during the swallow (Logemann,1993). Most VCRs are capable of recording timing information (by interfacing a counter time within the videotaping process) on each field (60 fields/sec) or frame (30 frames/sec) of the video study. However, calculating elapsed time for a specific event is often an involved process because it relies on identifying specific events with visual inspection and calculating times based on the fact that the videotape is being recording at a rate of 60 fields/second or 100 fields/second (Dengel, Robbins, & Rosenbek, 1991).

The videotape analysis of the modified barium swallow procedure is a process that is both time consuming and dependent on the viewer's subjectivity for the identification of the specific events. It frequently requires accessory equipment that many working clinicians may not have at their disposal. However, most clinicians have access to personal computers that are capable of running video editing software. The purpose of this paper is to discuss ways of helping the working clinician accomplish videofluorographic analysis and the calculation of transit times in a fast, economical manner. The following is a description of the videofluorographic analysis of a modified barium swallow procedure employing a protocol that includes the utilization of a video editing computer software program. This computer software program will be used to calculate transit times and to indicate at what time aspiration occurs.

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Software

Video Shop is a computer program that allows the user to capture video segments and edit these video segments for multimedia programs. Video Shop is currently distributed by Strata Software. For the clinician, it is a valuable program to use for the analysis of videofluorographic studies of the swallowing process as it allows the user to obtain temporal measurements immediately and view the video studies without time coding frame by frame for a micro analysis of the swallowing process.

Installation Procedures

1. Insert VideoShop CD into the CD ROM drive on the Macintosh.
2. Double-click on VideoShop Installer and follow the installation process to install VideoShop onto the your Macintosh.
3. Restart the computer after the installation process has been completed.

Recording Procedures

1. Connect the VCR to the appropriate video input jack. Newer Macintosh computers such as the Power Macintosh G3 & G4 have a video input jack already installed. For older Macintosh models, a video digitizing board and its software need to be installed on the computer.
2. Open VideoShop folder by double-clicking it.
3. Double-click the VideoShop application to launch VideoShop.
4. Choose Movie Recording (Figure 2) from the Windows menu (Figure 1). The Recording Window will appear. Turn on the VCR and locate the video segment to be recorded. Once the video tape is qued to the appropriate location, start the recording process by activating the play button on the VCR and the record button in the Recording Window. To save the video clip in the VideoShop folder, click on "File" then Save as" and name the file. Close the Recording window.

Figure 1. Windows menu.

 

Figure 2. Recording window.

Analyses Procedures

1. After closing the Recording window, the following windows will appear on the Macintosh desktop: Sequencer window, Canvas Window, Info palette, and Video Clips folder. Figure 3 displays the opened windows.

 

Figure 3. Sequencer window, canvas window, info palette, and video clips folder.

1. After video clip is saved, select the video clip file to analyze by dragging the video clip file from the Video Clips folder to the top track of the sequencer window. Figure 4 shows the file(s) available for analysis. Figure 5 displays the Sequencer window.

 

Figure 4. Recording folder.

 

Figure 5. Sequencer window. 

1. To view the selected video clip, click on the Play button in the Canvas window or press the space bar. Figure 6 shows the Canvas window, with an arrow indicating the Play button. To improve clarity of the video clip, access the Apple Studio Display panel (Figure 8) in the Macintosh Systems folder through the Control Panel (figure 7) and set the monitor display to 256 grays.

1. In order to analyze the video clip for temporal measurements, the video clip must be viewed in the Time View Mode. In the Sequencer window, click the Storyboard/Time View button to change to time view. The clock icon will appear when the Tme View Mode is active. Figure 9 displays the Time View Mode.

 

Figure 9. Time view mode.

1. A time line will be seen at the top of the sequencer to indicate the time of each frame in the sequence. Click on or near the time line and a vertical bar will appear. Figure 10 displays the vertical bar, which is activated by moving the cursor near the time line. Clicking a frame displays the corresponding frame in the canvas window, which will give you a larger view of the frame. This process allows you to search for any frame you want to analyze.

1. Before obtaining temporal measures make sure the Dur button is selected in the Info window. In order to obtain the temporal measure of the beginning frame and ending frame, position the vertical bar on the first frame and drag the vertical bar to the ending frame. Video clips are framed at the rate of 30 frames per second. Figure 10 shows an example of a selected segment of frames to be analyzed. The 24 in the Info window indicates a duration of 24 frames, which is equivalent to .8 second. 

 

Figure 11. Selected segment of video to be analyzed.

1. As you move the vertical bar, note the duration information in the Info Palette, which will displays the duration of the segment that was selected. You also can view the video in the Canvas window, which will give a clearer picture of the swallowing segment that is being analyzed. This process can be used to obtain the oral and pharyngeal transit temporal measurements. Figure 12 displays Information palette window temporal duration data.

Summary

Computer software designed for video editing provides a simple, fast, accurate, and economic means of aiding in the process of videofluorographic analysis. This type of program enables the clinician to enhance both the quality of the videofluorographic image and the accuracy of temporal measurements. A diagnostic tool such as this would help provide the working clinician with an simple and efficient means of assessing swallowing and identifying oral and pharyngeal disorders. Many times, it is cumbersome to review the videofluorographic studies with a slow motion video playback system as it is difficulty to locate the target segment to be analyzed.

References

Avid Technology, Inc. (1995). Videoshop. Tewksbury, MA.

Dengel, G., Robbins, J., and Rosenbek, J.C. (1991). Image processing in swallowing and speech research. Dysphagia, 6, 30-39.

Logemann, J. A. (1993). Manual for the Videofluorographic Study of Swallowing, Second Edition. Austin: Pro-Ed.

Strata Software, Inc. (2000). Videoshop. St. George, UT.

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