Coordinate Mapping of Hyolaryngeal Mechanics in Swallowing

Coordinate mapping is a method of documenting salient features of hyolaryngeal biomechanics in the pharyngeal phase of swallowing. This methodology uses image analysis software to record coordinates of anatomical landmarks. These coordinates are imported into an excel macro and translated into kinematic variables of interest useful in dysphagia research.

The overall goal of this procedure is to derive biomechanical data from modified barium swallow studies. This is accomplished by first reducing swallow studies in single swallow video clips. Next image J is configured to collect, coordinate data.

Then coordinates are mapped from anatomical landmarks. Finally, an Excel macro is used to convert, coordinate data into results. Ultimately, multiple kinematic measurements of interest are derived from the collection of coordinate data.

The main advantage of coordinate mapping over using line measurements to calculate displacement measurements is that adjustments for the movement of the subjects and the fluoroscope are automatically accounted for in the calculations embedded in the Excel macro. Furthermore, multiple measurements can be calculated from a single set of coordinates, and these coordinates can be used to run a morphometric analysis of degli tissue. This method can help answer key questions in the area of dysphagia research, such as changes in muscle mechanics due to treatment or impairment.

The implications of this technique extend toward the assessment and treatment of dysphagia because the impact of various etiologies of impairment can be documented and the efficacy of novel treatments can be determined. Though this method can be used with clinical imaging modalities to derive quantitative data has also been applied to research imaging such as dynamic magnetic resonance imaging of swallowing. Generally, individuals new to this method will struggle because image quality varies and swallowing is a complicated physiological process.

I first had the idea for this method when I was a graduate student, and I needed an efficient method for collecting data from kinematic and morpho metric analysis of swallowing using different imaging Modalities. Visual demonstration of this method is critical. Since multiple moving targets representing many frames of reference can confound mapping of key anatomical coordinates using fluoroscopy.

Getting valid and reliable measurements requires some interpretation of correct frame of reference and coordinate mapping After converting video files from various formats into DO MOV files according to the text protocol. To edit the clip length of a file, begin by using QuickTime. To open a MOV video file, identify five milliliter thin liquid and PUD swallows by audio cues or by swallow sequence.

Next, select edit trim and adjust the trimming bar so that the entire five milliliter thin fluid swallow is visualized. Then click, trim, select file, export, and create a file name that will be used to link the subject data to the coordinate mapping results. Trim the clip for the pudding swallow in a similar manner to de-identify images.

If a file contains any personal health information, use image J to upload the file using the rectangle tool to frame the swallowing study. To exclude personal health information, select image crop, then select file save as QuickTime movie. Configure the dialogue box by choosing compression syringe in three quality maximum, and enter the appropriate frame rate, which is usually 30 frames per second.

To take measurements, begin by opening image J.Click on the double forward arrow icon on the toolbar. Then select arrow labeling tools for uploading images. Click on the QuickTime icon on from the dropdown menu.

Select open movie as a stack and locate the edited QuickTime clip to process the images. To improve image quality, select process math add, check the preview box and adjust the numbers to the desired image quality. Choose yes to process the entire stack of images.

To set the measurements, select, analyze, set measurements In the dialogue box mark stack position and invert y coordinate and unmark everything else. Select the multi-point tool from the toolbar to mark anatomical landmarks. For example, click on the hyoid and the crico.

To use the multi-point tool, click on an anatomical landmark of interest. Take a measurement of all the points by selecting analyze measure from the menu. Useful commands for controlling the coordinates on the screen include using command A to remove all points.

Alternatively, remove single points by hovering over a point. Then using the command option keys and click on the point to be removed. To move a single point, hover over it, then click drag and drop it to a new location.

Use the arrow keys to move all points together to map landmarks. Begin at the first frame and advance to a clear frame. In the pre oral phase, observe the position of the bolus on the anterior superior margin of the tongue prior to initiation of oral transport of the swallow.

Use the image J Multipoint tool to map the first nine coordinates at the following anatomical landmarks, including the mandible, hard palate, tubercle of the atlas, C two C four, upper esophageal sphincter, posterior cricoid, anterior cricoid, and hyoid. Then use command M to record them. Advance the frames until the hyoid bone has reached maximum position in the anterior and superior directions.

Confirm the maximum position by advancing frames to ensure that descent of the hyoid begins on the following frame. Relocate points one through five to their new positions. These new positions will be recorded as coordinates 10 through 14.

Then relocate 0.9, which in turn becomes coordinate 18. Next, locate the frame depicting maximum laryngeal elevation. Adjust points seven and eight, which will serve as coordinates 16 and 17.

Then find frames representing the maximum excursion of the upper esophageal sphincter or UES 0.6. From the maximum hyoid frame, locate the frame where the bolus is impeded by the UES in the hypo pharynx. Adjust the coordinate point for UES from the minimum frame to represent UES maximum coordinate 15.

Use the command M keys to record the second nine coordinates for coordinates 19 and 20. Mark the edges of the scaler at the axis representing the longest diameter of the radiopaque marker. Use command M to record the coordinates.

If results are wanted in centimeters coordinates, 19 and 20 should be collected. Use either an American penny or a 1.9 centimeter ring. Use the following macro enabled Excel file to transform the coordinate data into kinematic measurements.

Note that trigono metric calculations embedded in the macros. Calculate the kinematic measurements. Download the coordinate mapping dot x LSM file from the JoVE article page.

Follow the instructions on the spreadsheet to initialize the file. The initialization macro will create three sheets, including results, data, and an input sheet. Finally, copy coordinates from the image J results window and paste into the designated cell in the input sheet.

Then run the data capture line. Macro results will appear on the results sheet. Lines of coordinate data will appear on the data sheet.

Intraclass correlation coefficients or iccs of coordinates collected by six investigators who independently analyzed 80 video fluoroscopic files were performed to demonstrate the reliability of the Raiders. Iccs were used to compare strings of variables by subject. This allowed for the determination of poor image quality leading to excluding the results from the subject in the analysis.

A breakdown of iccs by the following coordinate groupings is shown here. These results indicate that strong reliability between judges is achievable using coordinate mapping, iccs of 10 variables calculated from coordinates, collected from six independent raters by subject and bolus swallow revealed a single subject with poor ICC ratings. Visual examination of this MBS study confirmed poor image quality excluding this subject.

The mean of all iccs and 95%confidence intervals is 0.91, 0.84 to 0.96, excluding subject 15. The mean of all iccs equals 0.91 with a 95%confidence interval from 0.84 to 0.96 when comparing strings of variables by subject across six raters. This slide demonstrates that strong reliability among all trials can be visually associated with good image quality.

These results indicate that inter judge reliability of variables is useful to determine acceptable image quality. Shown here are the representative data showing comparisons of bolus differences. Significance is set at P is less than 0.005 with a bonferroni correction for multiple comparisons.

Although these results demonstrate the usefulness of this method, conclusions should not be drawn from them as age and gender were not controlled in this comparison. This table shows the results of this random sample, a Pearson correlation coefficient and a coefficient of determination of hyoid excursion calculated with the vertebrae as an axis of reference versus hyoid excursion compared with the mandible as an axis of reference for the five milliliter thin liquid and five milliliter pudding swallows is shown here. This result shows that hyoid movement is multifactorial.

If supra hyoid muscles solely displaced the hyoid, then these measurements would be strongly correlated. Hyoid excursion in reference to the vertebrae likely also accounts for extension of the head and neck, as well as supra hyoid muscle function. Once mastered, this technique can be done in less than 30 minutes when done properly.

While attempting this procedure, it's important to remember to adjust contrast on the videos so that the bolus in the landmarks can be easily identified Following this procedure. Other methods like morphometric analysis or coordinates can be performed in order to answer additional questions like the co-variant function of muscle groups and skeletal levers underlying hial, laryngeal elevation and swallowing. Since this development, this technique has been used in the field of dysphagia to determine the impact of new therapies such as transcranial, direct current stimulation on swallowing, and document swallowing difficulties in patient populations like Polytraumatized warriors with dysphagia as a result of blast injuries.

After watching this video, you should have a good understanding of how to acquire biomechanical data from modified barium swallowing studies using coordinate mapping of anatomical landmarks.