Prediction of Pharyngeal 3D Volume Using 2D Lateral Area Measurements During Swallowing

Area of Science:

• Deglutition physiology
• Medical imaging
• Biomechanical analysis

Background:

• Accurate pharyngeal volume assessment is crucial for understanding swallowing function.
• Traditional videofluoroscopic swallowing studies (VFSS) primarily use 2D imaging.
• The predictive capability of 2D pharyngeal area for 3D volume during swallowing requires further validation.

Purpose of the Study:

• To evaluate the accuracy of pharyngeal 2D area measurements from lateral views in predicting 3D pharyngeal volume in healthy adults during swallowing.
• To assess the influence of factors like height and sex on the predictive accuracy.
• To identify conditions where 2D measurements may lead to prediction errors.

Main Methods:

• Seventy-five healthy adults underwent 320-row area detector computed tomography (320-ADCT) while swallowing a barium bolus.
• Pharyngeal 2D area and 3D volume were measured before and during maximum pharyngeal constriction using dynamic 3D-CT imaging.
• Statistical analysis, including residual and outlier examination, was performed to assess predictive power (R²).

Main Results:

• Pharyngeal volume at rest (PVhold) was well predicted by 2D area (R² = 0.816), with improved prediction when including height and sex (R² = 0.836).
• Pharyngeal volume during maximum constriction (PVmax) also showed acceptable prediction by 2D area (R² = 0.777).
• Prediction errors increased with incomplete pharyngeal constriction and asymmetrical bolus flow or movement.

Conclusions:

• Lateral view 2D pharyngeal area measurements offer a valid method for predicting 3D pharyngeal volume, particularly at rest.
• Clinical interpretation of 2D measurements should consider potential inaccuracies arising from incomplete constriction or asymmetry.
• Routine incorporation of anterior-posterior views alongside lateral views in VFSS may enhance swallowing assessment accuracy.