Do Your Swallow Studies Measure Up?

October 22, 2015

Do Your Swallow Studies Measure Up?

A Blog about the Swallowtail software application from Belldev Medical, Inc.

Picture of a real swallowtail butterfly

by Karen Sheffler, MS, CCC-SLP, BCS-S of

(Disclosure: Nothing to disclose; No financial relationship)

Imagine yourself reviewing your patients’ Modified Barium Swallow studies with a fellow clinician. Does this sound familiar?

  • His swallow is a little delayed.
  • His hyolaryngeal excursion is a little bit better since he started therapy, don’t you think?
  • I think her residue is less now. It was moderate-severe on the Modified Barium Swallow 3 months ago, and now it is just mild-moderate.

Even when we standardize our protocol and use the validated MBSImp tool (Martin-Harris, et al., 2008), which helps us speak the same language in our rating and scoring system, we may still ask ourselves:

  • Can we demonstrate fine differences in our patient’s swallowing mechanics versus normal controls?
  • Can we document small improvements over time based on treatment or time post-onset?
  • Can we obtain accurate transit times in fractions of a second?
  • Can we show changes in maximum hyoid displacement with the following MBSImp Anterior Hyoid Excursion ratings: “No movement,” “Partial anterior movement,” and “Complete anterior movement”?
  • Can we show small improvements in pharyngeal physiology with the Pharyngeal Stripping Wave ratings of: “Absent,” “Diminished,” and “Complete”?
  • Can we show how functional the pharyngeal swallow is with descriptions of Pharyngeal Residue, such as: “Minimal to no clearance,” “Majority of bolus remains,” “Collection of residue,” “Trace residue,” and “Complete clearance”?

Swallowtail is a state-of-the-art software application (from Belldev Medical, Inc at that will have us thinking differently and generating quantitative and credible results.

I recently had the pleasure of discussing Swalowtail with Dominic A. Bellino, President of Belldev Medical, LLC and Rebecca Leonard, PhD, CCC-SLP, BCS-S, ASHA Fellow and Professor Emeritus in the Department of Otolaryngology at UC Davis.

This blog will review the metamorphosis of the Swallowtail software, which is a manifestation of years of work by Rebecca Leonard and Katherine Kendall, MD (see history section below).

The Potential of the Modified Barium Swallow:

Per Dr Rebecca Leonard, the Modified Barium Swallow used at UC Davis for many years includes a standardized protocol that is essentially uniform across patients, and a second portion customized to the individual patient. The protocol includes (as possible for individual patients): 1ml, 3ml and 20ml liquids, paste, cookie, straw-drinking, AP view with the largest bolus tolerated, and AP view with a barium tablet. Both study components, standardized and customized, are considered key to a thorough examination. Using Swallowtail, measurements are typically extracted, at least, for the largest bolus swallowed and allow the clinician to:

  1. Elaborate oral-pharyngeal swallowing mechanics in normal individuals and in patients with dysphagia.
  2. Plot your patient’s measurements against normative data matched, when appropriate, for gender and age (i.e., <65 years of age and >65 years of age).
  3. Provide evidence-based treatment directions (behavioral, surgical, medical treatments).
  4. Document changes in swallow function over time or treatment.
  5. Compare swallow mechanics across patient populations.
  6. Permit assessment of a patient’s aspiration risk, even when aspiration was not observed during the videofluoroscopic swallow study.
  7. Add to your ability to educate and counsel the patient.
  8. Maximize fluoroscopy time, which is important because it is an invasive procedure.

“We owe it to our patients,” per Leonard, “to extract the best, most complete information possible from this brief sample of the patient’s swallow function.”

  1. Improve your confidence in your recommendations.
  2. Improve your credibility with referral sources.

History of Swallowtail Software:

Bellino shared with me a brief history of the use of image processing for Modified Barium Swallow studies. He stated that our profession (swallowing and swallowing disorders) has been neglected by the medical industry. There are only about 20 articles in the literature on the use of image processing for the MBS, per Bellino. He wondered: “Why is it that cardiology has so many sophisticated tools, when swallowing is more complex than the human heart.” (Bellino recalled how it was Dr Reza Shaker, MD who compared swallowing function with cardiac function.) So here we are with only two main instrumental tools to evaluate swallowing (the MBS and the Fiberoptic Endoscopic Evaluation of Swallowing/FEES), which unfortunately both rely on visual perceptual judgements and subjective analysis.

We just needed a whole host of mathematicians and engineers on our side.

Bellino was initially inspired by Dr Joanne Robbins, PhD, CCC-SLP, BCS-S and her team’s work at the University of Wisconsin-Madison in 1991. Dengel, Robbins & Rosenbek (1991) created a Swallowing/Speech Interactive Image Processing Program (SIP) at The Swallowing and Speech Research Laboratory (SSRL) of the University of Wisconsin Department of Neurology and the William S. Middleton Memorial VA Hospital. Remember VCR tapes and analog images? If they could do this 25 years ago, then we can certainly move forward with digital image processing now. In 1991, Dengel, Robbins & Rosenbek concluded:

This rapidly expanding field offers tremendous potential for deriving more and better information from video imagery (p.37).”

Digital image processing for the Modified Barium Swallow Studies have been at the caterpillar stage for a long time.

Digital image processing for the Modified Barium Swallow Studies have been at the caterpillar stage for a long time.

Fast forward to 3 years ago, when Dominic Bellino met Dr Peter Belafsky, MD, PhD, MPH of UC Davis who directed him to Dr Rebecca Leonard.

Rebecca Leonard and Katherine Kendall, MD and Otolaryngologist (who is now at the University of Utah) had already been laboring more than 20 years to create measurement schemes to elaborate the oral-pharyngeal swallowing mechanics. I first saw Dr Leonard present a session at ASHA years ago, when software tools available at the time were in use at UC Davis, but few other sites. She showed how a penny taped to the chin helps calibrate the pixels to centimeters for displacement measurements, and how timing information could be superimposed on fluoroscopy recordings. She also demonstrated how ruler tools and other media software could be downloaded from the internet and applied to the MBS study. However, at that time the process seemed too daunting and time-consuming for most clinicians to consider.

The measurement process has been simplified thanks to the mathematicians and engineers who created the Swallowtail software. Leonard and Kendall (along with other advisors, listed on the Belldev Medical website) have tweaked the Swallowtail software application over the last 2 1/2 years to fit not only the Leonard/Kendall standard measurement schemes, but also to provide a tool to make any kind of temporal or linear measurement. Per Leonard: These data are considered valid and reliable, with intra-rater and inter-rater reliability at .85 – .90+ per internal testing, using 4 trained expert judges measuring over 150 studies of individuals with “normal” swallows. Excellent inter-rater reliability has also been demonstrated consistently in studies of individuals with dysphagia described in numerous research endeavors over the past several years (*See suggested references provided by Dr Leonard at the end of this article.)

Brief Introduction to the Measurement Schemes:

Per Leonard & Kendall’s chapters (2007, 2014), Leonard’s Swallowtail tutorials and a webinar on 10/16/15, two main categories of measurements are defined:

  1. Timing measures for bolus transit and swallow gestures (i.e., oropharyngeal transit time, PES opening duration, and more).
  2. Displacement measures (i.e., H Max: maximum displacement of the hyoid; HL Max: maximum approximation of the hyoid to the larynx during the swallow, and PES Max: greatest expansion of the PES during the swallow in lateral view and AP views; and more).

Within the category of displacement measures, I think the Pharyngeal Constriction Ratio (PCR) deserves special attention. It will be particularly useful in clinical practice. We often use informal terms like “functional swallow” and “non-functional swallow;” however, the PCR will numerically define how functional the pharyngeal constriction is. Leonard noted that the PCR correlates well with pharyngeal clearing pressures on manometry. Young adults may have a PCR close to zero (i.e., 0.03-0.04 for a 20ml swallow); however, an abnormally high PCR (e.g., 0.25) would indicate that the patient has reduced pharyngeal constriction and poor pharyngeal clearing during the swallow (See Leonard et al., 2011, for an open access article).

PCR = ratio of PA Max to the PA Hold (PA Max / PA Hold)

  • PA Max: boundaries of the pharynx, showing residual air space and bolus material, when the pharynx is maximally constricted at the height of the swallow.
  • PA Hold: shows the 2-dimensional area of the boundaries of the pharynx before the swallow when the structures are in a uniform, pseudo-rest position holding a 1ml bolus in the oral cavity.

Again, these are some of the measurement schemes created by Leonard and Kendall. You can compare your patient’s measurements to their normative data for the same size bolus (1ml, 3ml, 20ml). Additionally, you can set-up your own independent temporal or linear measurements to satisfy your own research or clinical questions.

Swallowtail’s Future:


The videofluoroscopic swallowing study has been considered a gold standard assessment tool for oral-pharyngeal dysphagia for decades. However, swallowing biomechanics are complex, and the absence of sophisticated image processing tools has made it difficult to quantitatively analyze fluoroscopic studies.

As a result, the full potential of VFS Studies has generally not been realized. The primary means of interpretation has been through subjective impressions. Though invaluable for some purposes, such as documenting aspiration or penetration, subjective determination of mechanical events is problematic, and can lead to poor reliability across raters.”

Swallowtail is currently working on FDA clearance to be clinic ready, but in the meantime, researchers, university professors and students can utilize this software application. It makes a perfect tool for research, as you can customize the quantitative measurements for your own purposes.

It facilitates teaching about normal and abnormal swallowing anatomy and physiology. I can picture students having an additional Dysphagia Lab semester, using Swallowtail along with MBSImp and other tools, analyzing everything from normal swallowing to very complex case studies. (See prior blog regarding dysphagia training in graduate schools.) Swallowtail has a library of modules for self-assessment, where you can compare your measurements against those made by the “alpha test sites.” Experts at these sites included doctoral students, physicians and professors from highly regarded university programs and medical centers.

Current challenges pointed out by Bellino and Leonard are:

  • Retaining clinician judgment in decisions regarding critical events and where they occur, while making the measurement process of these events as expedient and accurate as possible.
    a) The clinician identifies the exact frames on the video that correspond to bolus transit points, with the software then determining the temporal intervals between them.
    b) The clinician identifies and outlines boundaries of the pharynx at rest and maximally constricted (the bolus/air that remain at the height of the swallow), with the software calculating the actual areas for each, as well as the resulting ratio.
    c) The clinician draws a line between two points, such as between the anterior-inferior most point of the hyoid to the top of the tracheal air column (bottom of the larynx), at rest and maximally approximated, with the actual distance between hyoid and larynx then calculated by the software.
  • Time needed to make measurements.
  • Training needed to use the software and make accurate measurements.
  • May require a different mind-set, especially if you are used to making quick judgements based seeing the MBS in real-time, and not recording it for the essential further analysis. 

Dominic Bellino, President of Belldev Medical, LLC noted that it is a company goal to increase clinician guided automated measures to allow for a thorough analysis by the clinician in under 15 minutes. It is a balance between increasing automated measures and making sure that clinicians still use their expertise to perform their own independent analyses, per Leonard. In other words, you cannot automate the MBS fully; therefore, it is impossible to eliminate all variation. Never-the-less, it is certainly another company goal to narrow this range of potential variability.


Swallowtail is an “all-in-one” software application

to provide quantitative analysis of the

oropharyngeal swallowing mechanics in your 

swallow studies.

You can review your Modified Barium Swallow studies in real-time and frame-by-frame within the application, plot your data, export them to a spreadsheet or database, and consider them in addition to your qualitative analyses when assessing a patient’s swallow function. “Zoom” windows and controls for adjusting size, brightness and contrast of images aid the measurement process. Another benefit that Leonard reported was that the quality of her Modified Barium Swallow studies has improved, as she and her colleagues have sought better quality images in order to visualize key structures involved in measurement.

This quantitative analysis of Modified Barium Swallow studies satisfies two major points that have become part of my dysphagia practice (which are thanks to the influence of Dr James Coyle , PhD, CCC-SLP, BCS-S, who has repeated them numerous times, particularly at the ASHA Healthcare & Business Institute in April, 2014).

  1. Do not treat the bolus.”

Leonard also expressed concern when the clinician’s eye is only tracking the bolus during an MBS. She worries that significant information regarding swallowing mechanics can be missed. The “bolus,” after all, is contrast material that draws your eye to it. Structures responsible for moving the bolus through the aerodigestive tract are muted in shades of gray, and thus more difficult to appreciate. Per Leonard: Swallowtail helps you expand your focus to make accurate and reliable measures of bolus transit timing, swallow gesture timing, and displacements of structures key to safe and effective swallow.

  1. Diet changes cannot be outcome measures.”

We should be concerned when oral intake/diet scales, such as the FOIS (Functional Oral Intake Scale) or ASHA’s National Outcome Measurement System (NOMS), are the only indicators of progress in therapy or in research. We have to realize that many institutions do not even have standardized diets. Diet choices reflect patients’ preferences and their right to make their own decisions, regardless of the teams’ recommendations. If patients do consider the clinician-recommended diet, we have to realize that there is so much clinician variability in levels of acceptable risk. Swallowtail helps you justify your therapy with objective patient data of swallowing mechanics plotted against age-matched controls and gender-matched controls (when applicable), which is far more efficacious and informative than diet advancement.

In 1991, Joanne Robbins and the team at Wisconsin expected that digital image processing was just around the corner to provide a more detailed examination of our videoflouroscopic swallow studies (aka, Modified Barium Swallow Studies). Finally in 2015, Swallowtail has presented the field with a reliable and valid tool.

Are you ready to check out a Swallowtail webinar?

They are adding more webinars all the time. Contact the webinar coordinator at Belldev Medical, Inc if you are interested in signing up:


Martin-Harris, B. Brodsky, M.B., Michel, Y., Castell, D.O., Schleicher, M., Sandidge, J., Maxwell, R. & Blair, J. (2008). MBS Measurement tool for swallow impairment – MBSImp: Establishing a standard. Dysphagia, 23, 392-405.

Coyle, J.L. (2014, April). IIS5: Dysphagia Interventions: Are We Treating the Bolus, the Patient, or Something Else? Seminar presented at the Healthcare & Business Institute of the American Speech-Language-Hearing Association, Las Vegas, NV.

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

Leonard, R. (2007). Dynamic swallow studies: Measurement techniques. In R. Leonard & K. Kendall (Eds.), Dysphagia Assessment and Treatment Planning: A Team Approach, 2nd Edition (pp. 295-312). Plural Publishing, Co.: San Diego, CA.

Leonard R, Kendall K. (2014). Dysphagia Assessment and Treatment Planning: A Team Approach (3rd ed.) Plural Publishing, Co.: San Diego, CA (in press).

Leonard, R. (2015). Swallowtail Tutorial 4. Objective measures from flouroscopic swallow studies: A new tool from Belldev Medical, Inc. Courtesy of Belldev Medical, Inc.

*References provided by Dr Leonard:

Domer A, Leonard R, Belafsky PC. (2014). Pharyngeal weakness and upper esophageal opening in patients with unilateral vocal fold immobility. Laryngoscope, 124 (10), 2371-4.

Leonard R, White C, McKenzie S, Belafsky PC. (2014). Effects of bolus rheology on aspiration in dysphagic patients. J Acad Nutr Diet, 114 (4), 590-4.

Leonard R & Shaker R. (2013). Effects of aging of the pharynx and UES. Ch. 15 in Shaker R, Belafsky PC, Postma G, Easterling C. (Eds.) Principles of Deglutition: A Multidisciplinary Text for Swallowing and Its Disorders, Springer: New York.

Allen J, White CJ, Belafsky PC, Leonard R. (2012). Comparison of esophageal screen findings on videofluoroscopy with full esophagram results. Head and Neck, 34, 264-269.

Leonard R, Belafsky PC. (2011). Dysphagia following cervical spine surgery with anterior instrumentation: evidence from fluoroscopic swallow studies. Spine, 36, 2217-23.

Aminpour S, Leonard R, Fuller SC, Belafsky PC. (2011). Pharyngeal wall differences between normal younger and older adults. Ear Nose Throat J, 90(4), E1-5.

Allen J, White C, Leonard RJ, Belafsky PC. (2011). Posterior cricoid region fluoroscopic finding: The posterior cricoid placation. Dysphagia, 26, 272-276.

Leonard R, Rees CJ, Belafsky PC, Allen J. (2011). Fluoroscopic surrogate for pharyngeal strength: The pharyngeal constriction ratio. Dysphagia, 26, 13-17. (Note: Published online: 24 October 2009, Dysphagia). See Open Access article here:

Leonard R. (2010). Swallowing in the elderly: Evidence from fluoroscopy. Perspectives on Swallowing and Swallowing Disorders, 19, 103-114.

Belafsky PC, Rees CJ, Allen J, Leonard RJ. (2010). Pharyngeal dilation in cricopharyngeus muscle dysfunction and zenker diverticulum. Laryngoscope, 120, 889-894.

Allen J, White CJ, Leonard R, Belafsky PC. (2010). Effect of cricopharyngeus muscle surgery on the pharynx. Laryngoscope, 120, 1498-503.

Leonard R. (2010). Ablative procedures of the head and neck: implications for speech and swallowing. In: P. Donald (Ed), Head and Neck Cancer: Management of the Difficult Case. W.B.Saunders, Co.: Philadelphia, PA.

Fuller SC, Leonard R, Aminpour S and Belafsky PC. (2009). Validation of the pharyngeal squeeze maneuver. Otolaryngol. Head Neck Surg., 140, 391-394.

Aminpour S, Fuller S, Leonard R, Belafsky PC. (2008). Pharyngeal wall thickness in young and elderly normal subjects. Otolaryngol. Head Neck Surg., 139, 140-141.

Leonard R, Belafsky P, McKenzie S. (2008). Pharyngeal adaptation in Zenker’s diverticulum: The “faux pharyngoesophageal segment.” Otolaryngol. Head Neck Surg., 139, 424-428.

Leonard R, Belafsky PC, Rees CJ. (2007). Relationship between fluoroscopic and manometric measures of pharyngeal constriction: The pharyngeal constriction ratio. Ann. Otol. Rhinol. Laryngol., 115, 897-901.

Pollard RE, Marks SL, Leonard R, Belafsky PC. (2007). Preliminary evaluation of the pharyngeal constriction ratio (PCR) for fluoroscopic determination of pharyngeal constriction in dysphagic dogs. Vet. Radio. Ultrasound, 48, 221-226.

By Karen Sheffler

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