Topics

Topic

design image
Inferior tracheobronchial lymph nodes

The inferior tracheobronchial lymph nodes, also known as the subcarinal lymph nodes, are a key group of mediastinal lymph nodes located below the tracheal carina at the bifurcation of the trachea into the main bronchi. They lie in the posterior mediastinum, closely related to the bronchus intermedius (right side) and the left main bronchus, with the esophagus positioned posteriorly.

These lymph nodes are integral to the mediastinal lymphatic drainage system, filtering lymph from the lungs (particularly lower lobes), bronchi, esophagus, pericardium, and posterior mediastinum. They are clinically significant in lung cancer staging (N2 nodes), lymphoma, tuberculosis, and sarcoidosis. Enlargement of these nodes is often detected during chest imaging.

Synonyms

  • Subcarinal lymph nodes

  • Group 7 lymph nodes (per IASLC classification)

  • Inferior carinal lymph nodes

Function

  • Drain lymph from:

    • Lower lobes of both lungs

    • Bronchi and trachea

    • Esophagus and posterior mediastinum

    • Pericardium

  • Play a major role in immune defense of the thoracic cavity

  • Serve as a critical marker in lung cancer staging (N2 disease)

  • Frequently evaluated in mediastinoscopy and PET-CT

MRI Appearance

T1-weighted images:

  • Normal nodes: intermediate signal intensity similar to muscle

  • Enlarged or pathological nodes appear as rounded, intermediate-signal soft tissue structures beneath the carina

T2-weighted images:

  • Normal nodes: slightly hyperintense to muscle

  • Pathological nodes (e.g., with necrosis, edema, or inflammation) show higher signal intensity

  • Enlarged malignant nodes may demonstrate heterogeneous signal

T2 TRUFISP (cardiac/respiratory-gated):

  • Provides sharp visualization of mediastinal anatomy with bright blood contrast

  • Lymph nodes appear as discrete intermediate-to-high signal intensity structures against bright vascular and airway lumens

  • Helpful for assessing size, shape, and relationship to carina and bronchi

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, improving lymph node detection

  • Nodes appear as hyperintense structures, especially when inflamed or infiltrated

  • Sensitive for edema, infection, or malignant involvement

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Nodes enhance homogeneously when reactive or inflamed

  • Malignant nodes may show heterogeneous enhancement with necrotic or cystic areas

  • Useful for differentiating benign vs malignant lymphadenopathy

CT Appearance

Contrast-Enhanced CT (CECT):

  • Subcarinal nodes appear as oval or rounded soft tissue structures beneath the tracheal bifurcation

  • Normal nodes: ≤10 mm short-axis diameter

  • Enlarged nodes (>10 mm) suggest pathology (metastasis, infection, lymphoma)

  • Necrotic or malignant nodes show low attenuation with rim enhancement

  • CT is the primary modality for lung cancer staging, infection evaluation, and mediastinal mapping

MRI images

Inferior tracheobronchial lymph nodes anatomy mri coronal image -img-00000-00000

MRI images

Interlobar lymph nodes anatomy MRI coronal image -img-00000-00000

CT image

Inferior tracheobronchial lymph nodes anatomy CTi coronal image -img-00000-00000