Presentation on theme: "Imaging Anatomy of the Mediastinum"— Presentation transcript:
1Imaging Anatomy of the Mediastinum Dr. Flip OttoDept. of RadiologyUniversitas Academic Hospital
2Outline Mediastinal devisions Content of mediastinum Mediastinal contours on PA chest radiographCross sectional anatomy of mediastinumMediastinal lines and stripes on conventional radiography and CT correlationMediastinal spacesMediastinal lymphnodes
3Mediastinal devisions Devisions used to describe location of pathological processes:Superior mediastinum:Above line from lower border T4 to sternal angleAnterior mediastinum:Between anterior part of heart and sternumMiddle mediastinum:Occupied by heart and its vesselsPosterior mediastinum:Between posterior part of heart and thoracic spine
8Mediastinal contours on PA chest radiograph (from above downwards) Left side:Composite shadows of left subclavian vessels (artery lower and actually forms contour)Aortic knuckle formed by posterior part of archSmall “nipple” where left superior intercostal vein crosses aortaAortopulmonary windowLeft main pulmonary arteryLeft ventricleRight side :Right brachiocephalic veinSVCRight atrium (right heart border)Terminal part of IVC just medial to cardiophrenic angle
9Cross sectional Anatomy on CT T3 level 43561721-trachea 2-oesophagus 3-right braciocephalic vein4-left brachiocephalic vein 5-right brachiocephalic artery6-left common carotid artery 7-left subclavian artery
10Cross sectional Anatomy on CT T4 level 51231-trachea 2-aortic arch 3-oesophagus4-superior vena cava 5-arch of azygos vein
11Cross sectional Anatomy on CT T5 level 3172116851012491-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
17Anterior junction line Apposition of visceral and parietal pleura of anteromedial aspects of the lungs with intervening mediastinal fatOblique line crossing superior two thirds of sternum from upper right to lower leftIncreased mediastinal fat or thymus in younger patients lead to appearance as a stripeSuperior and inferior V-shaped recessesSeen on 24.5%-57% of frontal chest radiographsObliteration or abnormal convexity of line suggests anterior mediastinal disease such as thyroid masses, lymphadenopathy, neoplasms, thymic masses or lipomatosisVolume loss or hyperinflation of surrounding lung may displace the line
18Abnormal anterior junction line Volume loss in right lung with rightward displacement of anterior junction line following a right middle lobectomy
20Posterior junction line Apposition of visceral and parietal pleura of posteromedial portion of lungs posterior to oesophagus and anterior to T3-T5Straight or leftward convex line projecting through tracheaMay appear as stripe with intervening posterior mediastinal fatSuperior and inferior V-shaped recessesSeen on 32% of PA chest radiographsAbnormal bulging or convexity suggests posterior mediastinal abnormality such as oesophageal masses, lymphadenopathy, aortic disease or neurogenic tumours.Volume loss or hyperinflation of surrounding lung may displace the line
22Right paratracheal stripe Formed by visceral and parietal pleura of right upper lobe in contact with right lateral border of trachea and intervening mediastinal fat.Maximum normal thickness of 4mm.From level of clavicles superiorly to right tracheobronchial angle at the level of the azygos arch inferiorly.Seen on 97% of PA chest radiographsWidening or abnormal contour may be due to paratracheal lymphadenopathy, thyroid or parathyroid neoplasms, and tracheal carcinoma or stenosis. Pleural disease among most common causes for widening.
23Abnormal right paratracheal stripe Widening of right paratracheal stripe caused by a large ectopic parathyroid adenoma. Note diffuse osteopenia from hyperparathyroidism.
25Left paratracheal stripe Formed by contact between left upper lobe and mediastinal fat adjacent to left tracheal wall or wall itself.Extends from aortic arch superiorly to join with reflection from the left subclavian artery.Seen on 21%-31% of PA chest radiographs. May be obscured by contact between left lung and left common carotid artery anteriorly or left subclavian artery posteriorly.Abnormal contour or widening commonly due to pleural effusion, also due to left paratracheal lymphadenopathy, neoplasm or mediastinal haematoma.
26Abnormal left paratracheal stripe Widening of left paratracheal stripe with mass effect on the trachea due to large thyroid carcinoma and associated supraclavicular lymphadenopathy
28Posterior tracheal stripe Vertical stripe seen on lateral chest radiograph formed by air in trachea and right lung outlining posterior tracheal wall and intervening soft tissues.Up to 2.5mm in thicknessWhen posterior trachea in contact with anterior oesphageal wall may measure up to 5.5mm.Anterior border of retrotracheal space (Raider or retrotracheal triangle) with spine posteriorly and aortic arch inferiorly forming remaining borders.Most common abnormality in retrotracheal space is developmental anomalies of the aortic archAbnormal thickening also caused by acquired vascular lesion, oesophageal lesions, lymphatic malformations, mediastinitis and post-traumatic haematomas.
29Abnormal posterior tracheal stripe Widening of the posterior tracheal stripe due to dilated esophagus in a patient with achalasia.
31Posterior wall of bronchus intermedius Formed when lung within azygoesophageal recess outlines posterior wall of bronchus intermedius which continues to descend 3-4cm after take-off of the right upper lobe bronchus.Seen on 90%-95% of lateral chest radiographs.Thin, vertical or slightly oblique stripe projecting through radiolucent area created by left upper lobe bronchusNormally mm thickPulmonary oedema from congestive cardiac failure common cause for band-like thickeningOther causes for thickening include neoplasms and lymphadenopathy
32Abnormal posterior wall of bronchus intermedius Diffuse bandlike thickening of the posterior wall of the bronchus intermedius in a patient with pulmonary oedema.
34Right paraspinal lineFormed by right lung and pleura coming in tangential contact with posterior mediastinal soft tissuesThin white line enhancing edge of right paraspinal line due to positive Mach band phenomenonStraight line from T8-T12Seen on 23% of PA chest radiographsMay be displaced laterally by osteophytes or prominent mediastinal fatAbnormal contour or displacement may suggest posterior mediastinal abnormality such as mediastinal haematoma, a mass or extramedullary haematopoiesis.
35Abnormal 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.
37Left paraspinal lineFormed by tangential contact of left lung and pleura with posterior mediastinal fat, paraspinal muscles and adjacent soft tissues.Extends vertically from aortic arch to diaphragm medial to lateral wall of descending thoracic aorta, but may lie lateral along lower intrathoracic course of the aortaReported on 41% of PA chest radiographs. Seen more frequently than right because aorta promotes tangential contact of lungOsteophytes, prominent mediastinal fat, tortuosity of descending aorta, mediastinal haematoma, a mass, extramedullary haematopoiesis or oesophageal varices may displace line
38Abnormal left paraspinal line Focal lateral bulge in left paraspinal line due to extensive esophageal varices in patient with liver cirrhosis.
40Aortic-pulmonary stripe Represents mediastinal reflection formed by pleura of anterior left lung coming in contact with and tangentially reflecting over mediastinal fat anterolateral to the left pulmonary artery and aortic arch.Straight to mildly convex crossing laterally over aortic arch and main pulmonary artery.May be elevated in pneumomediastinum.Anterior mediastinal disease such as prevascular lymphadenopathy, thyroid or thymic masses may cause increased convexity laterally.
41Abnormal aortic-pulmonary stripe Abnormal contour of the aortic-pulmonary stripe due to lymphoma with anterior mediastinal lymphadenopathy within the prevascular space.
43Azygoesophageal recess Important mediastinal interface due to differences in density between mediastinum and posteromedial right lower lobeSpace lying lateral or posterior to oesophagus and anterior to the spine from level of arch of azygos to aortic hiatus inferiorlyRight infra-azygos pleuroesophageal stripe may outline recess when air filled oesophagus and intervening pleura come in contact with right lower lobeSuperioly and middle thirds may show mild leftward convexity. Lower third typically straight edge.Superior right convexity may be seen in the young, but is abnormal in the elderly.Abnormal contour may be due to lymphadenopathy, hiatal hernias, bronchopulmonary-foregut malformations, oesophageal neoplasms, pleural abnormalities and cardiomegaly with left atrial enlargement
44Abnormal azygoesophageal recess Abnormal contour and right lateral convexity of distal third of azygoesophageal recess due to a large hiatal hernia.
45Mediastinal spaces Four named spaces surrounding the central airways: Pretracheal spaceAortopulmonary windowSubcarinal spaceRight paratracheal space
47Aortopulmonary window Mediastinal space seen as interface on frontal chest radiographsLies posterior to aortic-pulmonary stripeBorders:Superior: Inferior wall of aortic archInferior: Superior wall of left pulmonary arteryAnterior: Posterior wall of ascending aortaPosterior: Anterior wall of descending aortaMedial: Trachea anteriorly, lateral wall of left main bronchus and oesophagus posteriorlyLateral: Left lung and pleura in contact with aortic arch and extending inferiorly to contact left pulmonary artery – forms interface representing AP window on frontal chest radiographs, normal concave reflection along mediastinal side. Convex contour abnormal.
48Abnormal aortopulmonary window - causes May be related to disease of contents: left recurrent laryngeal nerve; left vagus nerve; ligamentum arteriosum; mediastinal fat; lymph nodes; left bronchial arteriesAbnormal convexity may be due to prominent mediastinal fat, lymphadenopathy, bronchial artery aneurysms or nerve sheath tumoursParalysis of left vocal cord or diaphragm should prompt search for disease in AP windowDisease of structures forming borders of AO window e.g. aortic aneurysms can also cause abnormal appearance
49Abnormal 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.
50Mediastinal lymphnodes American Thoracic Society definitions of regional lymph node stationsX Supraclavicular nodes2R Right upper paratracheal nodes2L Left upper paratracheal nodes4R Right lower paratracheal nodes4L Left lower paratracheal nodes5 Aortopulmonary nodes6 Anterior mediastinal nodes7 Subcarinal nodes8 Paraesophageal nodes9 Right or left pulmonary ligament nodes10R Right tracheobronchial nodes10L Left tracheobroncheal nodes11 Intrapulmonary nodes
51ConclusionTraditional 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
52ReferencesButler, P., Mitchell, A.W.M., Ellis, H. (1999). Applied Radiological Anatomy. Cambridge: Cambridge University PressEllis, H., Logan, B.M., Dixon, A.K. (2007). Human Sectional Anatomy – Atlas of body sections, CT and MRI images, 3rd ed. London: Hodder ArnoldGibbs, 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 ElsevierRyan, S., McNicholas, M., Eustace, S. (2011). Anatomy for diagnostic imaging, 3rd ed. London: Saunders Elsevier