Morpho-functional patterns of physiologic oropharyngeal swallowing evaluated with dynamic fast MRI

Evaluation of velopharyngeal function using high-speed cine-magnetic resonance imaging based on T2-weighted sequences: a preliminary study

The objective was to introduce a new technique for visualizing the three-dimensional (3D) movements of velopharyngeal-related muscles using high-speed cine-magnetic resonance imaging (MRI) based on T2-weighted sequences. The evaluation of phonation- and water swallowing-related events was performed in 11 healthy subjects. Specifically, whether cine-MRI could precisely visualize normal velopharyngeal function during these two events was examined. The 3D movements of the soft palate, superior pharyngeal constrictor muscles, and levator veli palatini muscles were visualized in all 11 subjects. A noteworthy finding was that the magnetic resonance signals of the superior constrictor pharyngeal muscles and the levator veli palatini muscles were significantly higher during phonation and during water swallowing than at rest. This initial study suggests that the 3D movements of velopharyngeal-related muscles can be successfully and precisely visualized without side effects. The magnetic resonance signal changes seen in the superior pharyngeal constrictor and levator veli palatini muscles using the technique described here should be useful to develop better methods of evaluation of velopharyngeal function.

Assessing Upper Esophageal Sphincter Function in Clinical Practice: a Primer

The upper esophageal sphincter constitutes an important anatomic and functional landmark in the physiology of pharyngeal swallowing. A variety of clinical circumstances may call for a dedicated evaluation of this mechanism, from the etiologic evaluation of indeterminate symptoms to the generation of complex locoregional therapeutic strategies. Multiple diagnostic tools exist for the assessment of pharyngeal swallowing generally and of upper esophageal sphincter function specifically, some well established and others not yet settled into routine practice. This report reviews five specific modalities for use in making this assessment, outlining the strengths, weaknesses, and logistical considerations of each with respect to its potential use in clinical settings. In many cases, these studies will provide complementary information regarding pharyngeal function, suggesting the relative advantage of a multimodal evaluation.

The use of high-speed, continuous, T2-weighted magnetic resonance sequences and saline for the evaluation of swallowing

OBJECTIVE

To introduce a new high-speed, continuous, T2-weighted magnetic resonance imaging (MRI) technique for the evaluation of swallowing by visualizing the flow of saline.

STUDY DESIGN

In 20 healthy participants, high-speed (10 frames per second), continuous MRI of the pharynx and larynx was performed during administration of 5 mL of saline. The extent to which fluid flow and swallowing (including flow to the esophagus or trachea) could be visualized was determined for all 20 participants.

RESULTS

Solution flow was visualized, and swallowing events, including the direction of flow to the esophagus, could be visualized with high-speed, continuous MRI for all 20 participants.

CONCLUSIONS

This initial study suggests that the visualization of saline flow using our method may facilitate functional evaluation of swallowing without side effects.

Evaluation of swallow function after tongue cancer treatment using real-time magnetic resonance imaging: a pilot study

IMPORTANCE

Magnetic resonance imaging (MRI) has the advantage of imaging swallow function at any anatomical level without changing the position of patient, which can provide detailed information than modified barium swallow, by far the gold standard of swallow evaluation.

OBJECTIVE

To investigate the use of real-time MRI in the evaluation of swallow function of patients with tongue cancer.

DESIGN, SETTING, AND PARTICIPANTS

Real-time MRI experiments were performed on a Signa Excite HD 1.5-T scanner (GE Healthcare), with gradients capable of 40-mT/m (milli-Tesla per meter) amplitudes and 150-mT/m/ms (mT/m per millisecond) slew rates. The sequence used was spiral fast gradient echo sequence. Four men with base of tongue or oral tongue squamous cell carcinoma and 3 age-matched healthy men with normal swallowing participated in the experiment.

INTERVENTIONS

Real-time MRI of the midsagittal plane was collected during swallowing. Coronal planes between the oral tongue and base of tongue and through the middle of the larynx were collected from 1 of the patients.

MAIN OUTCOMES AND MEASURES

Oral transit time, pharyngeal transit time, submental muscle length change, and the distance change between the hyoid bone and anterior boundary of the thyroid cartilage were measured frame by frame during swallowing.

RESULTS

All the measurable oral transit and pharyngeal transit times of the patients with cancer were significantly longer than the ones of the healthy participants. The changes in submental muscle length and the distance between the hyoid bone and thyroid cartilage happened in concert for all 60 normal swallows; however, the pattern differed for each patient with cancer. To our knowledge, the coronal view of the tongue and larynx revealed information that has not been previously reported.

CONCLUSIONS AND RELEVANCE

This study has demonstrated the potential of real-time MRI to reveal critical information beyond the capacity of traditional videofluoroscopy. Further investigation is needed to fully consider the technique, procedure, and standard scope of applying MRI to evaluate swallow function of patients with cancer in research and clinic practice.

Dynamic real-time magnetic resonance imaging for the analysis of voice physiology

PURPOSE OF REVIEW

For a number of years, it has been possible to use dynamic real-time magnetic resonance imaging (MRI) to analyse the dynamic processes which occur in the human body. In the fields of laryngology and phoniatrics, such dynamic processes are found not only in swallowing, but also in voice and speech production. This article aims to present an overview of how the use of MRI might add to our current understanding of the dynamic processes involved in voice production.

RECENT FINDINGS

It is shown that up to now the analysis of vocal fold oscillations has been limited by MRI's relatively low sampling rate of up to 50 Hz. Nevertheless, more detailed analysis does seem possible with regard to the modulation of the power source and vocal tract.

SUMMARY

Dynamic real-time MRI offers a great opportunity for the analysis of voice production in all stages of the voice production system.

Intraoral pressure patterns during swallowing

Swallowing disturbances are common after neurological disease and oropharyngeal tumor resection. In this case the oral stage is often affected. So far the clinical evaluation of the oral phase is limited. Recently the role of pressure changes during oropharyngeal swallowing has been pointed out, but until now there are not enough data. Thereby 52 healthy adults aged between 20 and 45 years were examined using an oral shield (Silencos^®, Bredent, Senden, Germany) connected to a digital manometer (GDUSB 1000^®, Greisinger electronics, Regenstauf, Germany) able to record pressures in a range of 2,000 to −1,000 mbar at a frequency of 1 kHz. Three swallowing conditions were measured: an active bolus intake (ABI) of water, a passive bolus application of a water-bolus (PWA) and a passive application of a gel-bolus (PGA). We found negative pressures with a median value of −278.9 mbar during ABI, of −24.2 mbar during PWA and of −29.4 mbar during PGA. Significant differences in pressure amplitudes and the pressure pattern were observed depending on the kind of bolus application and its consistency. The used test presents a simple and easy to handle method to assess the oral phase of swallowing.

Relationship between Class III malocclusion and hyoid bone displacement during swallowing: a cine-magnetic resonance imaging study

Objective

The displacement of the hyoid bone (HB) is a critical biomechanical component of the swallowing function. The aim of this study was to evaluate the swallowing-induced vertical and horizontal displacements of the HB in subjects with 2 different magnitudes of skeletal Class III malocclusion, by means of real-time, balanced turbo-field-echo (B-TFE) cine-magnetic resonance imaging.

Methods

The study population comprised 19 patients with mild skeletal Class III malocclusion, 16 with severe skeletal Class III malocclusion, and 20 with a skeletal Class I relationship. Before the commencement of the study, all subjects underwent cephalometric analysis to identify the nature of skeletal malformations. B-TFE images were obtained for the 4 consecutive stages of deglutition as each patient swallowed 10 mL of water, and the vertical and horizontal displacements of the HB were measured at each stage.

Results

At all stages of swallowing, the vertical position of the HB in the severe Class III malocclusion group was significantly lower than those in the mild Class III and Class I malocclusion groups. Similarly, the horizontal displacement of the HB was found to be significantly associated with the severity of malocclusion, i.e., the degree of Class III malocclusion, while the amount of anterior displacement of the HB decreased with an increase in the severity of the Class III deformity.

Conclusions

Our findings indicate the existence of a relationship between the magnitude of Class III malocclusion and HB displacement during swallowing.

Real-time magnetic resonance imaging of normal swallowing

PURPOSE

To evaluate the use of a novel real-time magnetic resonance imaging (MRI) technique for the assessment of normal swallowing dynamics.

MATERIALS AND METHODS

In a cohort of 10 healthy subjects, real-time MRI movies at 24.3 frames per second were obtained in sagittal, coronal, and axial orientation during self-controlled swallows of 5 mL pineapple juice as oral contrast bolus. All studies were performed with the use of a commercial MRI system at 3 T combining two sets of radiofrequency receiver coils. Real-time movies relied on a fast low-angle shot (FLASH) MRI sequence with radial undersampling and image reconstruction by nonlinear inversion yielding 41.23 msec acquisition time for an in-plane resolution of 1.5 mm. Evaluations focused on clinical image quality as well as visualization and temporal quantification of distinct swallowing functions.

RESULTS

Throughout the entire process, the swallowing dynamics were well depicted and characterized with almost no visible image artifacts in all subjects. The mid-sagittal plane turned out to be most valuable. The movies allowed for a quantitative determination of the temporal pattern of all swallowing events.

CONCLUSION

The proposed real-time MRI technique yields noninvasive, robust, and quantitative access to the physiology of normal swallowing in healthy subjects at high temporal resolution and image quality.

Effect of complete denture wearing on deglutition time: a cine-magnetic resonance imaging study

Purpose of the study was to evaluate the effect of complete denture wearing on deglutition time (DT), hyoid bone and larynx movements in edentulous patients with real-time balanced turbo field echo cine-magnetic resonance imaging. Subjects were examined by cine-magnetic resonance imaging in supine position during swallowing water. Two sets of images for 23 edentulous (with/without wearing complete dentures) and one for 23 dentulous patients were obtained. Radiographic outputs representing three consecutive deglutition stages (oral, pharyngeal and oesophageal) were provided to perform measurements. Deglutition time significantly increased when edentulous patients wore their dentures (mean 0·75 s increased to 1·17 s), whereas dentulous patients' DT was about 0·91 s (P ≤ 0.05). The duration of deglutition is crucial because prolonged pharyngeal transit times increases the risk of aspiration. Within the limitations of the study, complete denture wearing could increase the shortened DT of the edentulous patients.