Mediastinum (ITMIG classification)

The International Thymic Malignancy Interest Group (ITMIG) classification of mediastinal compartments was developed to reflect a division of the mediastinum based on cross-sectional imaging. It was in part an effort to consolidate prior discrepant classification systems in use by different medical specialties. A working group composed of approximately 225 experts in thoracic surgery, medical oncology, diagnostic radiology, and pathology were tasked with forming a practical system for anatomic classification which unified the various systems.

Classification

The ITMIG classification divides the mediastinum into three compartments: prevascular, visceral and paravertebral ^1,2.

Prevascular compartment

Boundaries

• superior: thoracic inlet
• inferior: diaphragm
• anterior: posterior cortex of the sternum
• lateral: parietal mediastinal pleura
• posterior: anterior aspect of the pericardium

Contents

• thymus
• lymph nodes
• left brachiocephalic vein
• fat

Visceral compartment

Boundaries

• superior: thoracic inlet
• inferior: diaphragm
• anterior: posterior boundary of the prevascular compartment
• posterior: a vertical line connecting a point on each thoracic vertebral body 1 cm posterior to its anterior margin (visceral-paravertebral compartment boundary line)

Contents

• trachea/carina
• esophagus
• lymph nodes
• heart
• ascending aorta; aortic arch; descending thoracic aorta
• superior vena cava
• intrapericardial pulmonary arteries
• thoracic duct

Paravertebral compartment

Boundaries

• superior: thoracic inlet
• inferior: diaphragm
• anterior: posterior boundaries of the visceral compartment
• posterolateral: vertical line against the posterior margin of the chest wall at the lateral margin of the thoracic spine

Contents

• thoracic spine and paravertebral soft tissues