Soft Tissue Neck

Thorax and Abdomen

5 Soft Tissue Neck

Anatomy

Physiology note: The inhaled air column provides natural contrast, allowing visualization of the upper airway on radiographs.

Pathology examples:

Epiglottitis – acute, life-threatening swelling of the epiglottis; “thumb sign” on lateral.
Croup (laryngotracheobronchitis) – airway narrowing; “steeple sign” on AP.
Foreign body aspiration – radiopaque or radiolucent object causing partial or complete obstruction.
Related terminology – stridor (harsh breathing sound), dysphagia (difficulty swallowing), airway obstruction

CR Location & Positioning

SID: 72 inches (to minimize magnification)
Patient position: Upright, facing tube, MSP perpendicular to IR
Adjustments: Arms at sides, shoulders depressed, chin elevated slightly
CR: Perpendicular to IR at level of C4 (midway between laryngeal prominence and jugular notch); top of IR at EAM
Pt. Instructions: Take a deep breath in and hold it (full inspiration fills airway with air)
Exposure: On full inspiration

Evaluation Criteria

No rotation (sternoclavicular joints equidistant from spine).
Air-filled trachea and larynx visible from nasopharynx through proximal trachea, without superimposition of shoulders or chin.
No superimposition of mandible or base of skull over airway.
Sharp bony and soft tissue margins (no motion).

CR Location & Positioning

SID: 72 inches
Patient position: Upright, left lateral preferred, MCP perpendicular to IR
Adjustments: Shoulders depressed/pulled back, chin elevated slightly
CR: Perpendicular to IR at level of C4; top of IR at EAM
Pt. Instructions: Breathe normally or gently inhale (quiet inspiration prevents strain, especially if epiglottitis suspected)
Exposure: During inspiration

Evaluation Criteria

No rotation (cervical vertebrae in true lateral).
Air-filled upper airway visualized from nasopharynx to proximal trachea, without superimposition from chin or shoulders.
Hyoid bone and mandible not obscuring airway.
Clear, sharp soft tissue outlines; no motion blur.

Pediatric patients: Keep upright, avoid supine unless absolutely necessary. Use immobilization devices if needed. Minimize exposure time to reduce motion blur; use low mAs and appropriate kVp (75–85). Do not attempt without physician present in suspected epiglottitis.
Trauma patients: Cross-table lateral with horizontal beam if unable to sit/stand.
Large body habitus: Raise IR and CR to ensure airway is centered despite shoulder thickness.
Foreign body: AP and lateral images together localize the object.

kVp: 75–85 (slightly higher than bone studies to emphasize soft tissue contrast).
mAs: Low with short exposure time to prevent motion.
Collimation: From EAM superiorly to jugular notch inferiorly, narrow laterally to airway.
Shielding: Gonadal shielding.

Positioning & Image Quality

Why use full inspiration on AP?
Maximizes air column, improving contrast of airway structures.
How can you tell the AP image is not rotated?
Sternoclavicular joints equidistant from the spine; clavicles symmetrical.
How do you know exposure factors are appropriate?
Soft tissue margins (pharynx, trachea) clearly visible, cervical vertebrae still seen but not over-penetrated.
Why upright positioning in general?
Prevents airway collapse, especially in respiratory distress.
Why short exposure times?
To minimize motion blur from breathing or swallowing.

Clinical Rationale

Why is epiglottitis an emergency?
It causes sudden airway obstruction, especially in children. Radiographs must be obtained with extreme care.
Why should the patient remain upright?
Gravity helps keep airway open and reduces risk of complete obstruction.
Why obtain lateral for suspected epiglottitis?
The lateral demonstrates the swollen epiglottis (“thumb sign”) best.
What are common clinical indications for a soft tissue neck study?
Stridor, suspected foreign body, croup, epiglottitis, or upper airway obstruction.