Transposition of Dynamic MRI Data From Healthy Subjects to an in Vitro Swallowing Simulator
Condition: Imaging Data Collection From Dynamic Swallowing MRI in Healthy Volunteers; Create Operating Algorithms; Apply the Imaging Data of MRI to a Swallowing Simulator
Study type: Interventional

Summary: 
      Swallowing is a complex process, involving a very fine synchronization of the
      pharyngo-larynx, with respiration, under the control of the central nervous system and
      numerous peripheral effectors. Any dysfunction can lead to aspiration a source of morbidity
      and mortality.

      These dysfunctions of the aerodigestive tract affect a considerable number of patients with
      multiple etiologies: squamous cell carcinoma of the upper aerodigestive tract, peripheral or
      central neurological dysfunctions, neurosurgical or neurovascular causes, geriatric
      pathologies and intensive care complications.

      Aspiration pneumopathy is the most severe complication, which can lead to death. For decades,
      only techniques such as tracheotomy or enteral feeding (nasogastric tube/gastrostomy tube),
      associated or not with speech therapy, have been proposed to counter this problem. These
      invasive treatments remain symptomatic. These treatments bypass the pharyngolaryngeal
      dysfunction without resolving it and still significantly alter the patients' quality of life.

      In 2012, a first worldwide clinical study (published in the NEJM) based on 6 patients,
      conducted by the ENT team in Strasbourg, demonstrated an improvement in the quality of life
      of patients who had undergone total laryngectomy, by proposing the placement of a titanium
      laryngeal implant equipped with an upper valve. This strategy intended to avoid aspiration of
      food hile allowing normal breathing. Although this technique did not solve all problems (the
      persistence of food going the wrong way), this study allowed a conceptual change in the
      attempt to solve swallowing problems by the introduction of pharyngolaryngeal implants.

      The latter remains a challenge, but clinical trials of implants with a functional valve
      effected after removal of the larynx or on an existing but dysfunctional larynx have
      demonstrated the indivisibility of the pharynx-larynx couple in the search for permanent
      solutions.

      This physiological process can be studied with imaging. Videofluoroscopy is the reference
      method allowing a dynamic study of swallowing. However, it does not allow the study of soft
      tissue movement and exposes the patient to repeated irradiation. Recently, MRI has shown its
      ability to visualize the entire pharyngolaryngeal structures accurately and dynamically
      during the swallowing process.

      To improve the understanding and resolution of swallowing disorders, a unique robotic
      platform, consisting of a dynamic silicone skeleton reproducing the complexity of the
      pharyngolarynx, was initially developed by PROTIP MEDICAL (SWALL-E). This is the object of a
      French patent, transferred to the HUS University Hospitals of Strasbourg.

      The aim this study is to correlate and calibrate this platform with dynamic MRI data in
      healthy subjects, by studying the movement of the different anatomical structures of the
      pharyngolarynx during swallowing movements (speed, amplitude and synchronization of the
      pharyngolarynx movements).

      The immediate application of SWALL-E, after calibration and validation, will: i) allow the
      reproduction of a physiological swallowing mechanism; ii) allow to produce a pathological and
      personalized simulation of swallowing disorders in vitro; iii) allow the design of implants
      produced by 3D printing, and to analyze their effectiveness before implantation; iv) to
      modify in parallel and if necessary the rheology of the food boluses, thus contributing to a
      significant global improvement for the patient.

      Thus, this platform, unique in its conception, aims not only at making a diagnosis of the
      specific pathology of the patient, but also aims at a personalized management adapted to the
      patient, inexistent until now.

      Indeed, if the diagnostic methods are numerous (nasofibroscopy, swallowing transit,
      videofluoroscopy, study of swallowing noises by acoustic signals, swallowing
      cinetigraphy...), the treatments have remained identical for decades (speech therapy), and
      are not targeted (pharyngeal stimulation), despite the fact that each patient presents a
      specific pathology that is difficult to reunify under a "universal" treatment.
    

Detailed description: 
      To date, in vitro models of the pharyngeal phase of swallowing have led to limited results.
      No high-fidelity robot of the pharyngo-larynx has been developed.

      For this purpose, a robotic device, called SWALL-E (21) was created. It is based on a
      realistic anatomical model of a human pharyngolaryngeal tract in which the anatomical
      structures and mechanisms involved in the pharyngeal swallowing phase are precisely actuated
      and controlled. It allows to simulate a swallow in terms of dynamics, size, and timing by
      reproducing the anatomical structures directly involved in the bolus transport process of the
      pharyngeal phase (tongue base retraction; vocal cords opening/closing; larynx elevation;
      pharynx contraction; epiglottis tilt; upper esophageal sphincter opening/closing). SWALL-E,
      illustrated below, was designed with the main goal of reproducing with maximum fidelity the
      anatomy and physiology of the pharyngeal phase of adult human swallowing The SWALL-E platform
      is currently operational but has not yet been calibrated.

      The specifications were defined as follows: i) full-scale model of the adult human anatomical
      tract in a flexible material; ii) reproduction of the anatomical structures directly involved
      in the bolus transport process of the pharyngeal phase; iii) reproduction of the critical
      physiological mechanisms in an accurate and spatially and temporally adjustable manner.

      The mechanisms reproduced are i) bolus injection; ii) tongue base retraction; iii) vocal cord
      opening/closing; iv) laryngeal elevation; v) pharyngeal contraction; vi) epiglottis tilt;
      vii) upper esophageal sphincter opening/closing.

      The normal swallowing sequences performed demonstrated the ability of the system to reproduce
      the chronological order of biomechanical movements. This was achieved from clinical
      observations, and then adapted into a model whereby the movement and path of the food bolus
      can be physically imitated and controlled.

      SWALL-E is thus able to simulate the in vitro pharyngolaryngeal phase of "normal" swallowing
      by achieving a transit time comparable to that found in a healthy subject without any
      misdirection.

      The current SWALL-E kinetics were adjusted via subjectively obtained parameterizations by
      empirical observation of experienced clinicians (ENT) at nasofibroscopy. The dynamic MRI of
      swallowing will provide quantitative data on the velocities and amplitudes of the movements
      of the different anatomical structures present within SWALL-E: tongue base, epiglottis,
      pharyngeal constructor muscles, vocal cords and upper esophageal sphincter.

      Transposing the data collected via MRI will allow to improve the accuracy and coordination of
      the kinetics of the synthetically reproduced movements.

      Furthermore, by transposing the MRI data to SWALL-E, the investigators will be able to
      synchronize SWALL-E with data collected from any swallowing MRI performed in patients.

      To improve SWALL-E, it will be necessary to exploit objective numerical data: speed and
      amplitude of movement of the anatomical structures of the pharyngo-larynx, measured by
      swallowing MRIs. These numerical data will make it possible to create a typical
      parameterization to obtain a functioning of the device as close as possible to a "normal"
      (healthy) pharyngolaryngeal set. Once the "normal swallowing" settings are achieved, it will
      be possible to mimic different types of "pathological swallowing".

      The SWALL-E swallowing simulator (anatomical duct and simulation bench including such a duct)
      was the object of a national patent registration in 2017 (with a supplement in 2018), under
      the reference FR3071347A1, transferred to the University Hospitals of Strasbourg.

      Swall-E is controlled by Lab-Viex software but the data acquired at imaging will be processed
      on a video tracking software (APREX track-R&D) to then be transposed to SWALL-E.
    

Intervention name(s): Real-time MRI of swallowing
Intervention type(s): Other
Intervention description(s): The examination recording a total of 9 sequences of less than 30 seconds will be performed, in transverse section (passing through the epiglottis), frontal section, in the plane of the posterior pharyngeal wall, and in median sagittal section.
Each bolus of 20 ml will be administered in full, in one go, using a syringe. It is kept in the mouth for a few seconds and swallowed on demand.
The semi-liquid bolus of 20 ml comes from the mixture of 198 ml of pineapple juice to 10 gr of Nutilis Powder (NUTRICIA), food thickener containing neither gluten, nor lactose.
Ingredients: Dextrin-maltose, thickeners (modified starch (corn), tara gum, xanthan gum, guar gum).
3 sequences with no food
3 sequences with ingestion of a liquid bolus of 20 ml (pineapple juice) mouth closed
3 sequences with ingestion of a semi-liquid bolus of 20 ml (pineapple juice + Nutilis Powder) mouth closed
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: dysphagia; deglutition in normal subjects; swallowing; robotic in-vitro simulation