The integrity and functional stability of pharyngolaryngeal anatomical structures are critical for airway management, and the dynamic changes of key structures (e.g., pyriform sinus, cricoid cartilage lamina) during swallowing directly relate to the design and clinical safety of laryngeal masks. This observational study aims to investigate the real-time dynamic changes and physiological movement patterns of normal pharyngolaryngeal structures during barium swallow using routine barium meal examination imaging. The findings will provide anatomical and physiological evidence for optimizing laryngeal mask design and improving its anatomical fit with the pharynx and larynx.

After approval by the Ethics Committee of Zhejiang Cancer Hospital (Approval Number: IRB-2025-1096(IIT)), this study will be registered on ClinicalTrials.gov prior to participant enrollment. Given that the study only utilizes de-identified imaging data from routine barium meal examinations (no additional procedures or interventions for participants), informed consent is exempted as approved by the Ethics Committee. The study is planned to be conducted from August 2025 to October 2025.

Eligible participants are patients undergoing routine barium meal examinations at Zhejiang Cancer Hospital, meeting the inclusion criteria (18-75 years old, no pharyngolaryngeal surgery/trauma/congenital malformation, no swallowing dysfunction, unobstructed oropharyngeal-esophageal pathway, etc.) and excluding those with contraindications (e.g., goiter compressing pharyngolaryngeal structures, barium allergy).

Barium Swallow Examination Procedure:

All procedures follow the standard clinical protocol for barium meal examinations, with no additional radiation exposure or burden on participants:

Static Imaging (Resting State): Participants assume a standing position. A digital X-ray machine (Shimadzu Uni-vision) is used to obtain static images of the pharyngolaryngeal region, recording the baseline anatomical positions of the pyriform sinus, cricoid cartilage lamina, and esophageal inlet.

Dynamic Imaging (Swallowing State): Participants are instructed to swallow 5ml, 10ml, 20ml, and 40ml of medical barium sulfate suspension (concentration: 160-200% W/V) sequentially. During swallowing, a dynamic fluoroscopic imaging system is activated (frame rate: 15 frames/second) to continuously record the entire process of barium passing from the oropharynx through the larynx to the esophagus (each swallowing event lasts approximately 5-10 seconds). Each participant repeats the swallowing action 4-5 times, and the clearest dynamic image sequence is selected for subsequent analysis.

Data Collection and Analysis:

Image analysis software is used for frame-by-frame parsing of dynamic images. Key anatomical structures (pyriform sinus boundaries, anterior edge of the cricoid cartilage lamina, esophageal inlet center) are labeled, and coordinate positioning technology is applied to analyze the following parameters:

Displacement and angle changes of pharyngolaryngeal structures from resting state to peak swallowing phase; Preferred pathway of barium through the oropharynx (unilateral pyriform sinus, bilateral pyriform sinuses, or central region of the cricoid cartilage lamina); Retention time of barium in the pyriform sinus and its passing speed; Expansion amplitude of the pyriform sinus and displacement distance of the cricoid cartilage lamina during swallowing

Inclusion Criteria:

• Aged 18-75 years;
• No history of pharyngolaryngeal surgery, trauma, or congenital malformation;
• No swallowing dysfunction, pharyngolaryngeal inflammation, or neurological diseases affecting swallowing;
• No recent use of drugs that affect muscle function (e.g., muscle relaxants, anticholinergics);
• Barium meal examination confirms unobstructed oropharyngeal-esophageal pathway;
• Normal pharyngolaryngeal anatomical structure (confirmed by preliminary imaging review);
• Scheduled to undergo routine barium meal examination at Zhejiang Cancer Hospital for clinical diagnosis.

Exclusion Criteria:

• Presence of diseases that may compress pharyngolaryngeal structures (e.g., goiter, mediastinal mass);
• Allergy to barium sulfate or other components of the barium suspension.

Patient scheduled to take barium meal examination