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CT
Head and NeckDemonstration data

CT Soft-Tissue Neck

Contrast-enhanced CT of the soft tissues of the neck evaluates the suprahyoid and infrahyoid fascial spaces, lymph nodes, aerodigestive tract and vasculature. It is the primary modality for deep neck space infection and abscess and a key tool for nodal staging and characterisation of head and neck masses.

Indications

  • Suspected deep neck space infection, phlegmon or abscess
  • Nodal staging and detection of nodal metastasis in head and neck malignancy
  • Characterisation of a palpable or incidentally detected neck mass
  • Assessment of airway compromise from infection or mass
  • Evaluation of complications such as jugular thrombophlebitis (Lemierre syndrome) or vascular involvement

Contraindications & Cautions

  • Severe iodinated contrast allergy without adequate premedication
  • Significant renal impairment limiting intravenous contrast
  • MRI preferred for perineural spread, marrow invasion and detailed tumour delineation
  • Unstable airway requiring immediate management before imaging

Patient Preparation

  • Screen for iodinated contrast allergy and confirm renal function
  • Remove dental and neck jewellery to reduce artefact where feasible
  • Instruct on quiet respiration and suspended swallowing during acquisition
  • Consider puffed-cheek or phonation manoeuvres for oral cavity and laryngeal lesions

Technique & Parameters

  • Intravenous contrast (typically 80-100 mL) with imaging at approximately 60-90 seconds (soft-tissue phase)
  • Coverage from the skull base to the thoracic inlet
  • Thin collimation (≤1.25 mm) with axial, coronal and sagittal reformats
  • Angle the gantry or reformat to avoid dental amalgam streak artefact across key regions
  • Optimise timing to opacify the internal jugular veins and characterise nodal necrosis

Systematic Review

  • Assign pathology to fascial spaces (parapharyngeal, masticator, submandibular, carotid, retropharyngeal, visceral)
  • Assess lymph node levels (I-VII) for size, morphology and necrosis
  • Evaluate the mucosal surfaces of the pharynx and larynx for primary tumour
  • Inspect the airway for narrowing or displacement
  • Review vasculature for thrombosis, encasement or pseudoaneurysm and check for osseous erosion

Key Findings & Significance

  • Rim-enhancing low-attenuation collection with mass effect indicating abscess
  • Retropharyngeal fluid distinguishing suppurative abscess from oedema/effusion
  • Pathological nodes: short-axis enlargement, rounded shape, central necrosis or extranodal extension
  • Infiltrating enhancing primary tumour with deep space and airway involvement
  • Internal jugular vein thrombophlebitis with an oropharyngeal source (Lemierre syndrome)

Differential Considerations

  • Abscess versus phlegmon versus reactive lymphadenopathy
  • Necrotic metastatic node versus suppurative node versus branchial cleft cyst
  • Squamous cell carcinoma versus lymphoma versus salivary gland tumour
  • Second branchial cleft cyst versus cystic nodal metastasis (e.g. HPV-related)
  • Ludwig angina (submandibular/sublingual cellulitis) versus localised submandibular abscess

Pearls & Pitfalls

  • Extranodal (extracapsular) extension is a key adverse prognostic feature to report in nodal staging
  • Retropharyngeal abscess can extend into the danger space and mediastinum; assess the full craniocaudal extent
  • A cystic level II node in an adult should raise suspicion for HPV-associated oropharyngeal carcinoma
  • Report airway patency explicitly in infective and neoplastic disease to guide urgent management

Structured Report

  • Localise pathology to the involved fascial space(s) and give dimensions
  • For infection, distinguish abscess from phlegmon and describe airway impact
  • Stage nodal disease by level, size, necrosis and extranodal extension
  • Describe primary tumour extent, deep space invasion and vascular relationships
  • Note complications (vascular thrombosis, mediastinal extension) and recommend correlation as needed

References

  • ACR-ASNR-SPR Practice Parameter for the Performance of CT of the Extracranial Head and Neck
  • Radiographics: Gamss C et al. Imaging of the Deep Neck Spaces and Infections
  • AJCC Cancer Staging Manual: Head and Neck Nodal Staging
  • Radiographics: Aulino JM et al. Imaging Evaluation of the Suprahyoid and Infrahyoid Neck

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.