Imaging Anatomy of the MediastinumDr. Flip OttoDept. of RadiologyUniversitas Academic Hospital

Outline• Mediastinal devisions• Content of mediastinum• Mediastinal contours on PA chest radiograph• Cross sectional anatomy of mediastinum• Mediastinal lines and stripes on conventional

radiography and CT correlation• Mediastinal spaces• Mediastinal lymphnodes

Mediastinal devisionsDevisions used to describe location of pathological processes:• Superior mediastinum:• Above line from lower

border T4 to sternal angle• Anterior mediastinum:• Between anterior part of

heart and sternum• Middle mediastinum:• Occupied by heart and its

vessels• Posterior mediastinum:• Between posterior part of

heart and thoracic spine

Mediastinal contents

Mediastinal contours on PA chest radiograph

Cross sectional Anatomy on CTT3 level

12

3 45 67

1-trachea 2-oesophagus3-right braciocephalic vein4-left brachiocephalic vein 5-right brachiocephalic artery6-left common carotid artery 7-left subclavian artery

Cross sectional Anatomy on CTT4 level

1 23

45

1-trachea 2-aortic arch 3-oesophagus4-superior vena cava 5-arch of azygos vein

Cross sectional Anatomy on CTT5 level

123

456

7

89

10

1-main pulmonary trunk 2-right pulmonary artery 3-ascending aorta4-descending aorta 5-left main bronchus 6-right main bronchus7-superior vena cava 8-oesophagus 9-azygos vein10-azygoesophageal recess 11-left superior pulmonary vein12-left descending lower-lobe artery

11 12

Cross sectional Anatomy on CTT6 level

123

456

7

1-aortic root 2-right ventricular outflow tract 3-right atrial appendage4-left atrium 5-descending aorta 6-oesophagus7-azygos vein

Cross sectional Anatomy on CTT8 level

12

345

678

1-right atrium 2-right ventricle 3-left atrium4-left ventricle 5-left ventricular outflow tract and aortic valve6-descending aorta 7-oesophagus 8-azygos vein

Cross sectional Anatomy on CTT10 level

123 4

5

1-descending aorta 2-fundus of stomach 3-inferior vena cava4-oesophago-gastric junction 5-spleen

Mediastinal lines and stripes- Correlation between plain chest radiography and CT

• Lines:• Anterior junction line• Posterior junction line

• Stripes:• Right paratracheal stripe• Left paratracheal stripe• Posterior tracheal stripe• Posterior wall of bronchus intermedius

• Interfaces:• Right paraspinal line• Left paraspinal line• Aortic-pulmonary stripe• Azygo-oesophageal recess

Anterior junction line

Abnormal anterior junction line

Volume loss in right lung with rightward displacement of anterior junction line following a right middle lobectomy

Posterior junction line

Right paratracheal stripe

Abnormal right paratracheal stripe

Widening of right paratracheal stripe caused by a large ectopic parathyroid adenoma. Note diffuse osteopenia from hyperparathyroidism.

Left paratracheal stripe

Abnormal left paratracheal stripe

Widening of left paratracheal stripe with mass effect on the trachea due to large thyroid carcinoma and associated supraclavicular lymphadenopathy

Posterior tracheal stripe

Abnormal posterior tracheal stripe

Widening of the posterior tracheal stripe due to dilated esophagus in a patient with achalasia.

Posterior wall of bronchus intermedius

Abnormal posterior wall of bronchus intermedius

Diffuse bandlike thickening of the posterior wall of the bronchus intermedius in a patient with pulmonary oedema.

Right paraspinal line

Abnormal right paraspinal line

Abnormal bulge in right paraspinal line inferiorly due to mediastinal hematoma from multiple right sided transverse process fractures and an associated hemothorax.

Left paraspinal line

Abnormal left paraspinal line

Focal lateral bulge in left paraspinal line due to extensive esophageal varices in patient with liver cirrhosis.

Aortic-pulmonary stripe

Abnormal aortic-pulmonary stripe

Abnormal contour of the aortic-pulmonary stripe due to lymphoma with anterior mediastinal lymphadenopathy within the prevascular space.

Azygoesophageal recess

Abnormal azygoesophageal recess

Abnormal contour and right lateral convexity of distal third of azygoesophageal recess due to a large hiatal hernia.

Mediastinal spaces• Four named spaces surrounding the central

airways:• Pretracheal space• Aortopulmonary window• Subcarinal space• Right paratracheal space

Aortopulmonary window

Abnormal aortopulmonary window

Abnormal bulge in AP window due to significant soft tissue mass within AP window and subcarinal space compatible with metastatic lymphadenopathy in a patient with bronchogenic carcinoma. Also widened right paratracheal stripe due to lymphadenopathy and left lower lobe consolidation.

Mediastinal lymphnodes• American Thoracic Society

definitions of regional lymph node stations

• X Supraclavicular nodes• 2R Right upper paratracheal nodes• 2L Left upper paratracheal nodes• 4R Right lower paratracheal nodes• 4L Left lower paratracheal nodes• 5 Aortopulmonary nodes• 6 Anterior mediastinal nodes• 7 Subcarinal nodes• 8 Paraesophageal nodes• 9 Right or left pulmonary

ligament nodes• 10R Right tracheobronchial nodes• 10L Left tracheobroncheal nodes• 11 Intrapulmonary nodes

Conclusion• Traditional frontal and lateral chest radiography

remains a valuable tool in the evaluation of chest disease despite increased reliance on CT, therefore familiarity with anatomic basis of mediastinal lines and stripes as seen on radiography imperative.

• Knowledge of normal anatomic structures within different mediastinal divisions helps guide formulation of appropriate differential diagnosis

References• Butler, P., Mitchell, A.W.M., Ellis, H. (1999). Applied

Radiological Anatomy. Cambridge: Cambridge University Press

• Ellis, H., Logan, B.M., Dixon, A.K. (2007). Human Sectional Anatomy – Atlas of body sections, CT and MRI images, 3rd ed. London: Hodder Arnold

• Gibbs, J.M., Chandrasekhar, C.A., Ferguson, E.C. et al. (2007). Lines and Stripes: Where did they go? – From Conventional Radiography to CT. Radiographics, 27:33-48.

• Netter, F.H. (2011). Atlas of Human Anatomy, 5th ed. Philadelphia: Saunders Elsevier

• Ryan, S., McNicholas, M., Eustace, S. (2011). Anatomy for diagnostic imaging, 3rd ed. London: Saunders Elsevier