Cervical Lymph Nodes on CT/MRI

Measure / Thresholds

Key point There is no dedicated ACR incidental cervical lymph node table. Use short-axis size, morphology, location, and clinical context.

Measure cervical nodes by short-axis diameter on axial CT/MRI.
Most cervical nodal levels: suspicious at 10 mm or greater short axis.
Level II / jugulodigastric / subdigastric: suspicious at 11 mm or greater short axis.
Lateral retropharyngeal node: suspicious at 5 mm or greater short axis.
Medial retropharyngeal node: any visible node may be abnormal.

Three or more borderline nodes can be suspicious, especially in an expected drainage basin.
Common cluster criterion: each node 8 mm or greater short axis.
Level II / subdigastric cluster: each node greater than 9 mm short axis.

Central necrosis, cystic change, hypoenhancing center, or rim enhancement.
Irregular or indistinct margins, infiltration of adjacent fat or muscle, or extranodal extension.
Round shape is more suspicious than elongated/oval morphology.
Suspicious clustering can matter even if no single node crosses the usual size threshold.

Likely reactive: subcentimeter or level-appropriate, oval, homogeneous, smooth, and no necrosis or extranodal extension.
Indeterminate: mildly enlarged but homogeneous, no necrosis, no extranodal extension, and no suspicious primary lesion.
Suspicious: necrosis/cystic change, irregular margins, extranodal extension, clearly abnormal size, suspicious cluster, or associated primary lesion.

Benign/reactive: Scattered small cervical lymph nodes are present, favored reactive. No pathologically enlarged or morphologically suspicious cervical lymphadenopathy.
Mildly prominent/nonspecific: Mildly prominent [level/location] cervical lymph node measuring [x] mm short axis, homogeneous without necrosis or extranodal extension. Clinical correlation is recommended.
Suspicious: Abnormal [level/location] cervical lymph node measuring [x] mm short axis with [necrosis/cystic change/irregular margins/extranodal extension], suspicious for pathologic lymphadenopathy.

Likely reactive nodes usually need no imaging follow-up.
Indeterminate nodes: clinical correlation and ENT exam if persistent, enlarging, or unexplained.
Suspicious nodes: ENT referral and tissue sampling, typically ultrasound-guided FNA/core biopsy, as clinically appropriate.
Known or suspected cancer: dedicated staging work-up or oncology pathway.