Can a chest computed tomography (CT) scan view the axilla?

Can a Chest CT Scan View the Axilla?

Yes, a chest CT scan can visualize the axilla, as CT allows direct visualization of all three levels of axillary lymph nodes (levels I, II, and III) and surrounding structures. 1

Anatomic Coverage

• Chest CT routinely includes the axillary region in its field of view, providing cross-sectional imaging of axillary lymph nodes, vessels, chest wall, and soft tissues 2, 3
• CT provides superior visualization of level II and III axillary nodes compared to ultrasound, which may not adequately assess these deeper regions 1
• The axilla is typically captured in standard chest CT protocols that extend from the thoracic inlet through the lung bases 3

Clinical Utility and Limitations

When CT of the Axilla is Useful:

• Evaluating chest wall involvement and the relationship of disease to vital structures such as the axillary artery and vein 1
• Staging locally advanced breast cancer (>5 cm) or inflammatory breast cancer, where CT may be performed for systemic staging 1
• Assessing suspected chest wall invasion or bony involvement from axillary masses 1
• Detecting distant metastatic disease concurrently when axillary adenopathy is present 1

Important Limitations:

• CT is NOT routinely used for initial axillary lymph node assessment in breast cancer patients, even when nodes are clinically positive 1
• The predictive accuracy of CT is not high enough to replace sentinel lymph node biopsy or axillary lymph node dissection 1
• CT findings do not influence the surgical approach to the axilla, reduce the number of axillary surgeries, or reduce reoperation rates 1
• For evaluating axillary adenopathy, ultrasound with possible biopsy is the preferred initial modality due to its ability to guide tissue sampling 1

Common Clinical Scenarios

Incidental Axillary Findings:

• When axillary adenopathy is incidentally detected on chest CT, further evaluation with axillary ultrasound and possible US-guided biopsy is recommended 1
• This approach provides both morphologic assessment and the ability to obtain tissue diagnosis 4

Palpable Axillary Mass:

• If a chest wall lesion or axillary mass invading the chest wall is suspected, CT can determine bony involvement, chest wall involvement, or pleural space involvement 1
• However, ultrasound remains the initial imaging test of choice for characterizing palpable axillary masses 1

Suspected Metastatic Disease:

• CT is often used to evaluate biopsy-proven non-breast malignant axillary nodes to assess for systemic disease 1
• In patients with bilateral axillary adenopathy, CT may help identify lymphoma or other systemic malignancies 1

Key Clinical Pitfalls

• Do not rely on CT alone for axillary staging in breast cancer—ultrasound with biopsy provides higher specificity (98-100%) for nodal metastases 1, 2
• Hounsfield units of lymph nodes on CT may suggest metastatic involvement (higher values), but this is not sufficiently reliable for clinical decision-making 1
• CT cannot replace surgical staging (sentinel node biopsy or axillary dissection) in breast cancer management 1
• When CT incidentally shows axillary abnormalities, always correlate with clinical history and consider ultrasound-guided biopsy before making treatment decisions 1