back to basics: lateral chest radiograph - thoracic · pdf file93 sunday society of thoracic...
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Society of Thoracic Radiology
Annual Meeting and Postgraduate Course
Back to Basics: Lateral Chest RadiographBack to Basics: Lateral Chest Radiograph
March 11, 2012
Huntington Beach, California
Christopher Lee, M.D.
Cardiothoracic Imaging
Department of Radiology
Keck School of Medicine of USC
Disclosures
• None
Acknowledgements
• Robert Suh, M.D. (UCLA Medical Center)
Introduction
• Education and clinical importance of the lateral
chest radiograph have diminished as CT has
become more popular
– Ease of requesting (and recommending) a chest CT
when questionable abnormality seen on frontal CXR
• Radiology trainees, in particular, have
considerable difficulty in recognizing and
interpreting the subtleties of the lateral
Learning objectives
• Review fundamental anatomy, variations, and
spaces routinely revealed on the lateral CXR
• Correlate the perspective the lateral viewCorrelate the perspective the lateral view
provides with that provided by multiplanar CT
• Reinforce an appreciation of the value of the
lateral chest radiograph
Outline
• Trachea
• Retrotracheal space (Raider triangle)
• Large airways
A t i d i• Arteries and veins
• “Three clear spaces”
• Inferior hilar window
Back to Basics: Lateral Chest RadiographChristopher Lee, MD
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Trachea
• Easily recognizable
• Anterior tracheal stripe
– Appreciated only on occasionAppreciated only on occasion
• Mediastinal fat
• Air/lung
– May not be visibly altered even in the presence of
extensive pretracheal pathology
Trachea
• Posterior tracheal stripe
– Outlined posteriorly by air in right lung or esophageal
lumen and anteriorly by air in tracheal lumen
– Variable appearance, 1-5 mm
• Posterior tracheal wall only: thin line
• Posterior tracheal wall, intervening tissue,
collapsed esophagus: thicker stripe or band
Trachea
• Posterior tracheal stripe
– Outlined posteriorly by air in right lung or esophageal
lumen and anteriorly by air in tracheal lumen
– Abnormal appearance
• > 5.5 mm
• Persistently thickened on serial radiographs
Trachea
• Posterior tracheal stripe
– Outlined posteriorly by air in right lung or esophageal
lumen and anteriorly by air in tracheal lumen
– Abnormal appearance
• > 5.5 mm
• Persistently thickened on serial radiographs
Trachea
• Posterior tracheal stripe
– Outlined posteriorly by air in right lung or esophageal
lumen and anteriorly by air in tracheal lumen
– Abnormal appearance
• > 5.5 mm
• Persistently thickened on serial radiographs
Retrotracheal space
• Retrotracheal space (“Raider triangle”)
– Boundaries
• Anterior posterior tracheal wall-right lung
• Posterior thoracic vertebral bodies
• Superior thoracic inlet
• Inferior aortic arch-left lung
– Size varies with age, body habitus, and lung inflation
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Retrotracheal space Retrotracheal space
Retrotracheal space
• Retrotracheal space (“Raider triangle”)
– Boundaries
– Contents
Esophagus
Left recurrent laryngeal nerve
Thoracic duct
Lymph nodes
Lungs
Retrotracheal space
• Retrotracheal space (“Raider triangle”)
– Boundaries
– Contents
– Pathology
Congenital vascular lesions
Acquired vascular lesions
Esophageal abnormalities
Mediastinal masses
Infections
Retrotracheal space
i d l l i
esophageal abnormalities
Zenker diverticulum
achalasia
esophageal atresia
duplication cyst
esophageal leiomyoma
congenital vascular lesions
left aortic arch with aberrant right subclavian artery
right aortic arch with aberrant left subclavian artery
double aortic arch
Franquet et al. Radiographics 2002; 22:S231-246
acquired vascular lesions
aneurysm of aberrant subclavian artery
aortic aneurysm
esop agea y
esophageal carcinoma
mediastinal masses
intrathoracic goiter
schwannoma /neurofibroma
hemangioma
lymphatic malformation
hematoma
infections
tuberculous/pyogenic mediastinitis
abscess
Retrotracheal Space
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Large airways
McComb. J Thorac Imaging 2002; 17:58-69
Large airways
Large airways
Courtesy of Robert Suh, M.D.
Large airways
• Right upper lobe bronchus (RUL)
– Projects between aortic arch and left pulmonary
artery
Large airways
• Right upper lobe bronchus (RUL)
– Anterior margin closely related to RUL artery
– Superior margin closely related to azygous vein
Large airways
• Right upper lobe bronchus (RUL)
– Inconsistently visualized
– Increasing conspicuity contiguous pathology
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Large airways
• Left main-upper lobe continuum (LULC)
– Consistently visualized distinct landmark
– Projects below left pulmonary artery
Large airways
• Left main-upper lobe continuum (LULC)
– Projects below left pulmonary artery (LPA)
• LPA (superior and posterior)
• Left superior pulmonary vein (inferior and anterior)
Large airways
• Left main-upper lobe continuum (LULC)
– Continuum along left mainstem into LUL bronchus
• Variable in size and shape
• Occasionally, round lucency within round lucency
Large airways
• Left main-upper lobe continuum (LULC)
– Continuum along left mainstem into LUL bronchus
• Variable in size and shape
• Occasionally, round lucency within round lucency
Large airways
• Left main-upper lobe continuum (LULC)
– Continuum along left mainstem into LUL bronchus
• Variable in size and shape
• Occasionally, round lucency within round lucency
Large airways
• Posterior wall of bronchus intermedius
– Intermediate stem line
– Continuous with right mainstem bronchus, terminating
at origin of RLL superior segmental bronchus
– Approximated posteriorly by azygoesophageal recess
– Typically projects over LULC
• Foretells rotation
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Large airways
• Posterior wall of bronchus intermedius
– Intermediate stem line
– Continuous with right mainstem bronchus, terminating
at origin of RLL superior segmental bronchus
– Approximated posteriorly by azygoesophageal recess
– Typically projects over LULC
• Foretells rotation
Large airways
• Posterior wall of bronchus intermedius
– Intermediate stem line
– Continuous with right mainstem bronchus, terminating
at origin of RLL superior segmental bronchus
– Approximated posteriorly by azygoesophageal recess
– Typically projects over LULC
• Foretells rotation
Large airways
• Posterior wall of bronchus intermedius
– Intermediate stem line
– Continuous with right mainstem bronchus, terminating
at origin of RLL superior segmental bronchus
– Approximated posteriorly by azygoesophageal recess
Large airways
• Posterior wall of bronchus intermedius
– Abnormal > 3 mm
Large airways
• Posterior wall of bronchus intermedius
– Abnormal > 3 mm
Large airways
• Posterior wall of bronchus intermedius
– Abnormal > 3 mm
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Large airways
• Posterior wall of bronchus intermedius
– Abnormal > 3 mm
Arteries and veins
• Left pulmonary artery (LPA)
– Short posterosuperior and lateral mediastinal course
– When outlined superiorly by air, resembles “miniature
aortic arch”
Arteries and veins
• Left pulmonary artery (LPA)
– Short posterosuperior and lateral mediastinal course
– When outlined superiorly by air, resembles “miniature
aortic arch”
Arteries and veins
• Left pulmonary artery (LPA)
– Obscured superior border
• AP window lymphadenopathy
– Lobulated posterior border
• Hilar lymphadenopathy
Arteries and veins
• Left pulmonary artery (LPA)
– Obscured superior border
• AP window lymphadenopathy
– Lobulated posterior border
• Hilar lymphadenopathy
Arteries and veins
• Left pulmonary artery (LPA)
– Obscured superior border
• AP window lymphadenopathy
– Lobulated posterior border
• Hilar lymphadenopathy
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Arteries and veins
• Right pulmonary artery (RPA)
– In actuality, “right hilar vascular opacity”
– Conglomerate of pulmonary arteries and veins
Arteries and veins
• Right pulmonary artery (RPA)
– Longer lateral mediastinal course than LPA
– Divides at the edge of the mediastinum
– RPA = upper aspect of right hilar vascular opacity
– Interlobar artery = lower aspect of rt hilar vasc opacity
– Poorly marginated secondary to branching and lack of
adjacent lung
Arteries and veins
• Right pulmonary artery (RPA)
– Longer lateral mediastinal course than LPA
– Divides at the edge of the mediastinum
– RPA = upper aspect of right hilar vascular opacity
– Interlobar artery = lower aspect of rt hilar vasc opacity
– Poorly marginated secondary to branching and lack of
adjacent lung
Arteries and veins
• Right pulmonary artery (RPA)
– Longer lateral mediastinal course than LPA
– Divides at the edge of the mediastinum
– RPA = upper aspect of right hilar vascular opacity
– Interlobar artery = lower aspect of rt hilar vasc opacity
– Poorly marginated secondary to branching and lack of
adjacent lung
Arteries and veins
• Right pulmonary artery (RPA)
– Enlargement of right hilar vascular opacity with
lobulated contour
• Hilar lymphadenopathy
Arteries and veins
• Right ventricular outflow tract
• Ascending thoracic aorta
• Variable visibility• Variable visibility
– Approximation of lung and fat to anterior borders
– Alignment with path of x-ray beam
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Arteries and veins
• Right ventricular outflow tract
• Ascending thoracic aorta
Arteries and veins
• Right ventricular outflow tract
• Ascending thoracic aorta
Arteries and veins
• Inferior vena cava (IVC)
– Occasionally, anterior wall also outlined by lung
Arteries and veins
• Inferior vena cava (IVC)
– Occasionally, anterior wall also outlined by lung
Arteries and veins
• Left brachiocephalic vein
– Retromanubrial opacity
McComb. J Thorac Imaging 2002; 17:58-69
Arteries and veins
• Superior vena cava
• Right brachiocephalic vein
• Innominate artery
• Right subclavian artery• Right subclavian artery
• Composite S-shaped opacity on lateral
radiograph
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Arteries and veins
• Superior vena cava
• Right brachiocephalic vein
• Innominate artery
• Right subclavian artery• Right subclavian artery
McComb. J Thorac Imaging 2002; 17:58-69
Three clear spaces
• “Spine sign”
– Increasing lucency as progress
down thoracic vertebral bodies
• Less soft tissue attenuation in
l h t ll d tlower chest wall compared to
upper chest wall/shoulders
Three clear spaces
• “Spine sign”
– Two types of abnormalities
• Localized opacity with discrete edge
– Lung mass or consolidation
– Mediastinal mass
• Increased density without edge
– Pleural thickening/disease
– Lower lobe collapse
Three clear spaces
• “Spine sign”
– Two types of abnormalities
• Localized opacity with discrete edge
– Lung mass or consolidation
– Mediastinal mass
• Increased density without edge
– Pleural thickening/disease
– Lower lobe collapse
Three clear spaces
• “Spine sign”
– Two types of abnormalities
• Localized opacity with discrete edge
– Lung mass or consolidation
– Mediastinal mass
• Increased density without edge
– Pleural thickening/disease
– Lower lobe collapse
Three clear spaces
• Anterior clear space
– Increasing lucency as progress superiorly from the
densest portion of the heart
• Decreasing width of anterior mediastinum,
b i i t PA/ di t l l tbeginning at PA/ascending aorta level to
SVC/brachocephalic veins
– Variable degree of lucency
• Amount of lung protruding behind manubrium
• Women have decreased retrosternal lucency
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Three clear spaces
• Anterior clear space
– Increasing lucency as progress superiorly from the
densest portion of the heart
• Decreasing width of anterior mediastinum,
b i i t PA/ di t l l tbeginning at PA/ascending aorta level to
SVC/brachocephalic veins
– Variable degree of lucency
• Amount of lung protruding behind manubrium
• Women have decreased retrosternal lucency
Three clear spaces
• Anterior clear space
– Increasing lucency as progress superiorly from the
densest portion of the heart
• Decreasing width of anterior mediastinum,
b i i t PA/ di t l l tbeginning at PA/ascending aorta level to
SVC/brachocephalic veins
– Variable degree of lucency
• Amount of lung protruding behind manubrium
• Women have decreased retrosternal lucency
Three clear spaces
• Anterior clear space
– Opacification with our without discrete edge
• Anterior mediastinal mass
• Lung mass or consolidation
Three clear spaces
• Retrocardiac clear space
– Increasing lucency as progress inferiorly from
between the posterior border of heart and anterior
vertebral bodies (infrahilar)
D i idth f di ti• Decreasing width of mediastinum
– Esophagus and azygous vein
– Air-filled right lower lobe (azygoesophageal
recess)
Three clear spaces
• Retrocardiac clear space
– Increasing lucency as progress inferiorly from
between the posterior border of heart and anterior
vertebral bodies (infrahilar)
D i idth f di ti• Decreasing width of mediastinum
– Esophagus and azygous vein
– Air-filled right lower lobe (azygoesophageal
recess)
Three clear spaces
• Retrocardiac clear space
– Opacification with or without discrete edge
• Lung or mediastinal mass (m. common hiatal hernia)
• Lung consolidation (edge represents major fissure)
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Inferior hilar window
• Sub-area of retrocardiac clear space
– Avascular area along anteroinferior hilar composite
– Boundaries
• Right middle lobe bronchus
• Left lower lobe bronchus
– Devoid of nodular opacities > 1 cm
Inferior hilar window
• Sub-area of retrocardiac clear space
– Avascular area along anteroinferior hilar composite
Inferior hilar window Inferior hilar window
Inferior hilar window Inferior hilar window
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Inferior hilar window
Courtesy of Robert Suh, M.D.
Inferior hilar window
Courtesy of Robert Suh, M.D.
Inferior hilar window
Courtesy of Robert Suh, M.D.
Conclusions
• The lateral chest radiograph provides a
perspective that significantly enhances the
evaluation for thoracic disease
• Awareness of routinely visualized anatomic
structures and spaces should facilitate improved
interpretation of conventional chest radiographs
Posttest question
• On a properly positioned (i.e. non-rotated) lateral
radiograph, the posterior wall of the bronchus
intermedius projects over which structure?
a) Right upper lobe bronchus
b) Right hilar vascular opacity
c) Left main-upper lobe continuum
d) Left pulmonary artery
References
1) Franquet T, Erasmus JJ, Gimenez A, et al. The retrotracheal space: normal
anatomic and pathologic appearances. Radiographics 2002; 22:S231-S246.
2) McComb BL. The chest in profile. J Thorac Imaging 2002; 17:58-69.
3) Park CK, Webb WR, Klein JS. Inferior hilar window. Radiology 1991;
178:163-168.
4) Feigin D. Lateral chest radiograph: a systematic approach. Acad Radiol) g g p y pp
2010; 17:1560-1566.
5) Landay MJ. Anterior clear space: how clear? How often? How come?
Radiology 1994; 192:165-169.