Evaluation of the anatomical and functional properties of deglutition with various kinetic high‐speed MRI sequences

Abstract

We evaluated various fast MR sequences for obtaining anatomical and dynamic functional information during deglutition. Seven healthy volunteers underwent MRI of the oropharynx during swallowing of an oral positive-contrast agent. Single-slice imaging was performed in the median sagittal plane while subjects were in a supine position. Twenty serial images were obtained using EPI, FLASH, and turbo-FLASH sequences. The dynamic (movement-related) information and the anatomical resolution of the soft tissues were evaluated during deglutition. The FLASH sequence provided high-quality images at rest. During swallowing, however, the images were significantly degraded by movement artifacts and had inferior temporal resolution. The EPI evidenced better temporal resolution, but was degraded by strong distortions and movement arti- Index terms: fast MRI; dynamic MRI; swallowing; pharyngeal physiology; degluition DEGLUTITION IS THE COMPLEX COORDINATED AC-TIVITY of multiple voluntarily and involuntarily contracted muscles of the oropharynx, the larynx, and the upper digestive pathway. The motion of the involved anatomical structures while swallowing is very rapid: the mean duration of the oral and pharyngeal phases during bolus propulsion is approximately 1 second (1). The evaluation of the functional properties of the anatomical structures involved in swallowing has been severely impeded by the low temporal resolution of conventional, spin-echo, magnetic resonance imaging (MRI) sequences. Recent advances with ultra-fast MRI sequences now provide the opportunity to image softtissue motion with "near" real-time temporal resolution.Various high-speed MRI techniques, such as echoplanar imaging (EPI) and turbo-fast low-angle shot (turbo-FLASH), have been used to obtain dynamic images of soft tissues during physiological motion (2-4). The application of these sequences to the oropharynx and the upper digestive pathway to evaluate deglutition function has resulted in images with a satisfactory spatial and temporal resolution. The rapid swallowing motion can be adequately evaluated dynamically, with good recognition of the involved anatomical structures, in acquisition times below 1 second. Better delineation of the oropharyngeal apparatus can be achieved with the application of an oral positive-contrast agent as a food bolus substitute.The aim of the present study was to evaluate the ability of various available high-speed MRI sequences to dynamically image the deglutition process, and to determine which sequence provided the best dynamic (movement-related) information and anatomical resolution of the oropharyngeal soft tissues involved in each of the swallowing phases. The value of this technique as a diagnostic tool will be discussed in the context of the routinely used radiographic and endoscopic techniques. METHODSSeven healthy volunteers (five males and two females, age range: 25-35 years) with no history of oropharyngeal diseases participated in the study. A 1.5 T superconducting MRI system (Gyroscan ACS-NT, Philips Medical S...

The physiological linkage between molar inclination and dental macrowear pattern

“…The correct posture of the tongue (Van Dyck et al, 2016) seems one of the most promising solutions to this problem, further stressing the importance of tongue in the rehabilitation from oral disorders. Therefore, it could be possible that the physiological asymmetries in the masticatory system of the studied human group is attributable to the posture of the tongue which, in addition to all other muscles involved in swallowing, exerts a force that is absorbed by the hard palate (Anagnostara et al, 2001; Hartl et al, 2003; Lear et al, 1965; Mosier et al, 1999; Palmer et al, 2008; Pameijer et al, 1970). When swallowing takes place correctly, the tip of the tongue presses firmly against the roof of the mouth or hard palate, which is located slightly behind the front teeth.…”

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“…Anagnostara et al (5) reported that the turbo fast low-angle shot (Turbo-FLASH) sequence achieved 0.15-0.3 seconds/ slice using a 1.5T MRI system (Gyroscan ACS-NT; Philips Medical Systems, Best, The Netherlands). Barkhausen et al (10) reported that the true fast imaging with steady precession (TrueFISP) sequence produced 0.139 -0.405 seconds/image using a 1.5T MRI system (Magnetom Vision, Siemens, Erlangen, Germany).…”

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