3D-CT Evaluation of Swallowing: Metrics of the Swallowing Response Using Swallowing CT

Abstract

Videofluoroscopy and videoendoscopy dramatically changed the evaluation and management of swallowing disorders. Later advancements in techniques for the instrumental evaluation of swallowing were limited by technique and positioning. The advent of 320-row area detector CT solved previous challenges and allowed for the study of swallowing physiology and dysphagia in greater detail. In this summary, we describe the history and evolution of CT technology and describe research and clinical applications for the evaluation of swallowing physiology and pathophysiology.

Keywords: Computed tomography; Deglutition; Deglutition disorders; Evaluation; Larynx; Pathophysiology; Pharynx; Physiology; Rehabilitation; Swallowing; Upper esophageal sphincter.

Fig. 1

Development of CT

Fig. 2

CT images from previous studies. Axial images acquired from Electron Beam Computed Tomography at the level of glossopalatal junction (a), at the level of valleclae (b), and at the level of UES (c), cited Figs. 2–4 of Ergun’s study [18]. d Three-dimensional modeling of oropharyngeal swallow using the images of synchronized EBCT and VF. Cited Figs. 2 and 3 of Kahrilas’s study [19]. e Axial images at the level of UES (white arrows), cited Fig. 6 of Lindbichler’s study [20]. f Axial images of PES before swallowing and during swallowing of dry swallow (upper) and jelly swallowing (lower), cited Fig. 2 of Takehara and Chu’s study [22]. Reproduced with permission from [18, 19, 20, 22]

Fig. 3

3D-CT images of swallowing in healthy volunteer (upper two rows) and in dysphagia patient (lower two rows). In both swallows, upper row is lateral view and lower row is posterior view. Yellow is bolus and blue is air column surface. Arrows show the penetration and aspiration

Fig. 4

Aquilion ONE (Canon Medical) and reclining position in 320-row area detector computed tomography (320-ADCT) using offset-Sliding CT Chair. Left: Aquilion ONE Right: reclining position—30° from the upright

Fig. 5

MPR images and 3D-CT images of Upper esophageal sphincter from various perspectives. Left: MPR images (upper: mid-Sagittal section, middle: coronal section, lower: axial section). Right: 3D-CT images (upper: lateral view, middle: posterior view, lower, superior view)

Fig. 6

Temporal measurement and Kinematic measurements. a Temporal measurement: timing of events correlated with onset of rapid hyoid antero-superior movement as time zero. UOP upper orpharyngeal, VAL Valleculae, ESO esophagus. b Measurement of Pharyngo-laryngeal volume and bolus volume in pharyngeal cavity. Left: volume of air (blue line) and liquid barium (yellow) in the pharynx over time. The onset of rapid hyoid antero-superior movement is the zero reference time (vertical line). Right: 3D-images of pharyngeal cavity at the beginning of the swallow (1) and at the maximum pharyngeal contraction (2) according to the definition of pharyngeal cavity. c Measurement of the UES cross-sectional area. Cross-sectional area of UES while UES is opening. The onset of rapid hyoid antero-superior movement is the zero reference time. UES started to open 0.3 s after the hyoid antero-superior movement and was opened for 0.5 s. d Measurement of the distance between origin and insertion of the suprahyoid muscles and thyrohyoid muscles. Lateral (1) and anterior (2) views of mandibular bone, hyoid bone, thyroid cartilage, and cranial bone are illustrated. For both 1 and 2 left images are at the beginning of swallow and right images are at maximum hyoid displacement

Fig. 7

3D-CT images of one healthy volunteer’s swallow of honey thick liquid and thin liquid. Lateral image (upper) and transverse image (view of true vocal cord from below) (lower) at the onset of hyoid anterosuperior movement during honey thick liquid (a) and thin liquid (b). At the onset of hyoid anterosuperior movement, honey thick bolus was transported to valleculaetrue and vocal cord (TVC) was still open. Meanwhile, thin liquid bolus was transported to hypopharynx, lower than that of honey thick, and TVC was closed already