Cervical lymph node metastases refer to regional nodal involvement by cancer in the head and neck, most commonly due to squamous cell carcinoma originating from the aerodigestive tract or skin. Radiologic detection of cervical lymph node metastases is important for clinical staging and planning of surgery and radiotherapy.
Radiographic features
CT and MR
Various criteria have been proposed to predict metastatic involvement of a cervical lymph node on CT and MR:
- short-axis diameter in axial plane ≥10 mm, except 1
- ≥11 mm in level II (subdigastric region) 1
- ≥5 mm in the lateral retropharyngeal group 2
- any visible in the medial retropharyngeal group 2
- longest axial diameter cutoff criteria depend on which performance characteristic is of most interest (the following applies to level II and III nodes) 4:
- maximise the sum of sensitivity and specificity: ≥12-15 mm
- maximise sensitivity (98%) and negative predictive value: ≥5 mm
- cluster of three or more borderline nodes (each ≥8 mm short-axis diameter, except >9 mm in the level II/subdigastric region) 1
- long-to-short axis ratio <2 (i.e. rounder) 3
- necrotic/cystic areas (low attenuation on CT, focal high T2 signal intensity on MR, hypoenhancing area with or without rim enhancement) 1,2
- evidence of extranodal extension, including indistinct nodal margins, irregular nodal capsular enhancement, and infiltration into adjacent fat or muscle
Some studies compared the relative value of these different features, finding that minimal axial (short-axis) diameter was a better classifier for metastatic disease than maximal axial (long-axis) diameter or longest coronal (longitudinal) diameter 1,5. The presence of necrotic/cystic areas is also highly predictive of metastatic disease compared to benign nodes in patients with head and neck cancer 5.
PET
- intense 18F-FDG uptake
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