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Superior vena cava

The superior vena cava (SVC) is a large systemic vein that drains deoxygenated blood from the head, neck, upper limbs, and upper thorax into the right atrium of the heart. It is formed by the confluence of the left and right brachiocephalic veins behind the first right costal cartilage.

The SVC descends vertically along the right side of the superior mediastinum, anterior to the trachea and posterolateral to the ascending aorta. It enters the right atrium at the level of the third costal cartilage. The azygos vein is its major tributary.

Clinically, the SVC is critical in venous return, central venous access, and pathology such as SVC syndrome, thrombosis, or external compression from tumors. It is a key structure evaluated in oncology, interventional radiology, and cardiology.

Synonyms

  • SVC

  • Anterior vena cava

  • Vena cava superior

Function

  • Collects systemic venous blood from the upper body (head, neck, thorax, arms)

  • Returns blood to the right atrium for pulmonary circulation

  • Important route for central venous catheters, pacing leads, and dialysis catheters

  • Landmark for mediastinal imaging and interventions

Tributaries

  • Right and left brachiocephalic veins

  • Azygos vein

  • Small mediastinal and pericardial veins

MRI Appearance

T1-weighted images:

  • Lumen appears as a signal void (black) due to venous flow

  • Vessel wall is hypointense, surrounded by mediastinal fat (hyperintense)

T2 TRUFISP (cardiac-gated):

  • Depicts SVC as a bright, well-defined vascular lumen with sharp contrast against surrounding tissue

  • Provides dynamic cine evaluation of venous flow, patency, and compression

  • Excellent for detecting thrombosis, stenosis, or extrinsic compression (e.g., tumor, enlarged lymph nodes)

STIR (Short Tau Inversion Recovery):

  • Suppresses fat to highlight perivascular edema or inflammation

  • SVC lumen remains dark; surrounding pathology becomes hyperintense

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • SVC lumen enhances homogeneously and brightly

  • Filling defects represent thrombus, tumor invasion, or stenosis

  • Critical for MR venography of thoracic veins

MRA (Magnetic Resonance Angiography):

  • Contrast-enhanced MRA provides high-resolution 3D imaging of SVC and tributaries

  • Visualizes stenosis, thrombosis, compression, anomalies, or collateral circulation

  • Useful for mapping in SVC syndrome or interventional planning

CT Appearance

Contrast-Enhanced CT (CT Venography):

  • SVC lumen opacifies brightly with contrast, clearly delineating vessel course

  • Identifies stenosis, thrombosis, compression, intraluminal mass, or collateral venous pathways

  • Multiplanar and 3D reconstructions provide precise mapping for oncologic staging, venous stenting, or filter placement

CT images

Superior vena cava anatomy CT axial image -img-00000-00000

CT images

Superior vena cava anatomy CT CORONAL image -img-00000-00000

CT image

Superior vena cava anatomy MRI CORONAL image -img-00000-00000