Download Basics: Lateral Chest Radiograph

Back to Basics: Lateral Chest Radiograph
Society of Thoracic Radiology
SUNDAY
Christopher Lee, MD
Disclosures
Annual Meeting and Postgraduate Course
• None
Back 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
Acknowledgements
Introduction
• Robert Suh, M.D. (UCLA Medical Center)
• 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
Outline
• Review fundamental anatomy, variations, and
spaces routinely revealed on the lateral CXR
•
•
•
•
•
•
• Correlate the perspective the lateral view
provides with that provided by multiplanar CT
• Reinforce an appreciation of the value of the
lateral chest radiograph
Trachea
Retrotracheal space (Raider triangle)
Large airways
A t i and
Arteries
d veins
i
“Three clear spaces”
Inferior hilar window
93
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Trachea
Trachea
• Easily recognizable
• Posterior tracheal stripe
• Anterior tracheal stripe
– Appreciated only on occasion
• Mediastinal fat
• Air/lung
– May not be visibly altered even in the presence of
extensive pretracheal pathology
Trachea
Trachea
• Posterior tracheal stripe
• 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
– 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
Retrotracheal space
• Posterior tracheal stripe
• Retrotracheal space (“Raider triangle”)
– 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
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– 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
– 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
Retrotracheal space
Retrotracheal space
Retrotracheal space
• Retrotracheal space (“Raider triangle”)
• Retrotracheal space (“Raider triangle”)
– Boundaries
– Contents
à Esophagus
à Left recurrent laryngeal nerve
à Thoracic duct
à Lymph nodes
à Lungs
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Retrotracheal space
– Boundaries
– Contents
– Pathology
à Congenital vascular lesions
à Acquired vascular lesions
à Esophageal abnormalities
à Mediastinal masses
à Infections
Retrotracheal space
congenital vascular lesions
left aortic arch with aberrant right subclavian artery
right aortic arch with aberrant left subclavian artery
double aortic arch
acquired
i d vascular
l llesions
i
aneurysm of aberrant subclavian artery
aortic aneurysm
infections
tuberculous/pyogenic mediastinitis
abscess
Franquet et al. Radiographics 2002; 22:S231-246
esophageal abnormalities
Zenker diverticulum
achalasia
esophageal atresia
duplication cyst
esophageal
esop
agea leiomyoma
y
esophageal carcinoma
mediastinal masses
intrathoracic goiter
schwannoma /neurofibroma
hemangioma
lymphatic malformation
hematoma
Retrotracheal Space
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Large airways
Large airways
McComb. J Thorac Imaging 2002; 17:58-69
Large airways
Large airways
• Right upper lobe bronchus (RUL)
– Projects between aortic arch and left pulmonary
artery
Courtesy of Robert Suh, M.D.
Large airways
Large airways
• Right upper lobe bronchus (RUL)
• Right upper lobe bronchus (RUL)
– Anterior margin closely related to RUL artery
– Superior margin closely related to azygous vein
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– Inconsistently visualized
– Increasing conspicuity Æ contiguous pathology
Large airways
• Left main-upper lobe continuum (LULC)
• Left main-upper lobe continuum (LULC)
– Consistently visualized distinct landmark
– Projects below left pulmonary artery
– Projects below left pulmonary artery (LPA)
• LPA (superior and posterior)
• Left superior pulmonary vein (inferior and anterior)
Large airways
Large airways
• Left main-upper lobe continuum (LULC)
• Left main-upper lobe continuum (LULC)
– Continuum along left mainstem into LUL bronchus
• Variable in size and shape
• Occasionally, round lucency within round lucency
– Continuum along left mainstem into LUL bronchus
• Variable in size and shape
• Occasionally, round lucency within round lucency
Large airways
Large airways
• Left main-upper lobe continuum (LULC)
• Posterior wall of bronchus intermedius
– Continuum along left mainstem into LUL bronchus
• Variable in size and shape
• Occasionally, round lucency within round lucency
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Large airways
– 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
Large airways
• Posterior wall of bronchus intermedius
• 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
Large airways
• Posterior wall of bronchus intermedius
• 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
– Abnormal > 3 mm
Large airways
Large airways
• Posterior wall of bronchus intermedius
• Posterior wall of bronchus intermedius
– Abnormal > 3 mm
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– 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
– Abnormal > 3 mm
Arteries and veins
• Posterior wall of bronchus intermedius
• Left pulmonary artery (LPA)
– Abnormal > 3 mm
– Short posterosuperior and lateral mediastinal course
– When outlined superiorly by air, resembles “miniature
aortic arch”
Arteries and veins
Arteries and veins
• Left pulmonary artery (LPA)
• Left pulmonary artery (LPA)
– Short posterosuperior and lateral mediastinal course
– When outlined superiorly by air, resembles “miniature
aortic arch”
– Obscured superior border
• AP window lymphadenopathy
– Lobulated posterior border
• Hilar lymphadenopathy
Arteries and veins
Arteries and veins
• Left pulmonary artery (LPA)
• Left pulmonary artery (LPA)
– Obscured superior border
• AP window lymphadenopathy
– Lobulated posterior border
• Hilar lymphadenopathy
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Large airways
– Obscured superior border
• AP window lymphadenopathy
– Lobulated posterior border
• Hilar lymphadenopathy
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Arteries and veins
Arteries and veins
• Right pulmonary artery (RPA)
• Right pulmonary artery (RPA)
– In actuality, “right hilar vascular opacity”
– Conglomerate of pulmonary arteries and veins
–
–
–
–
–
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
Arteries and veins
• Right pulmonary artery (RPA)
• 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
–
–
–
–
–
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
Arteries and veins
• Right pulmonary artery (RPA)
• Right ventricular outflow tract
• Ascending thoracic aorta
– Enlargement of right hilar vascular opacity with
lobulated contour
• Hilar lymphadenopathy
• Variable visibility
– Approximation of lung and fat to anterior borders
– Alignment with path of x-ray beam
100
Arteries and veins
• Right ventricular outflow tract
• Ascending thoracic aorta
• Right ventricular outflow tract
• Ascending thoracic aorta
Arteries and veins
Arteries and veins
• Inferior vena cava (IVC)
• Inferior vena cava (IVC)
– Occasionally, anterior wall also outlined by lung
– Occasionally, anterior wall also outlined by lung
Arteries and veins
Arteries and veins
• Left brachiocephalic vein
•
•
•
•
– Retromanubrial opacity
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Arteries and veins
Superior vena cava
Right brachiocephalic vein
Innominate artery
Right subclavian artery
• Composite S-shaped opacity on lateral
radiograph
McComb. J Thorac Imaging 2002; 17:58-69
101
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Arteries and veins
Three clear spaces
•
•
•
•
• “Spine sign”
Superior vena cava
Right brachiocephalic vein
Innominate artery
Right subclavian artery
– Increasing lucency as progress
down thoracic vertebral bodies
• Less soft tissue attenuation in
l
lower
chest
h t wallll compared
d tto
upper chest wall/shoulders
McComb. J Thorac Imaging 2002; 17:58-69
Three clear spaces
Three clear spaces
• “Spine sign”
• “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
Three clear spaces
• “Spine sign”
• Anterior clear space
– 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
102
– 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
– Increasing lucency as progress superiorly from the
densest portion of the heart
• Decreasing width of anterior mediastinum,
b i i att PA/
beginning
PA/ascending
di aorta
t llevell tto
SVC/brachocephalic veins
– Variable degree of lucency
• Amount of lung protruding behind manubrium
• Women have decreased retrosternal lucency
Three clear spaces
• Anterior clear space
• Anterior clear space
– Increasing lucency as progress superiorly from the
densest portion of the heart
• Decreasing width of anterior mediastinum,
b i i att PA/
beginning
PA/ascending
di aorta
t llevell tto
SVC/brachocephalic veins
– Variable degree of lucency
• Amount of lung protruding behind manubrium
• Women have decreased retrosternal lucency
– Increasing lucency as progress superiorly from the
densest portion of the heart
• Decreasing width of anterior mediastinum,
b i i att PA/
beginning
PA/ascending
di aorta
t llevell tto
SVC/brachocephalic veins
– Variable degree of lucency
• Amount of lung protruding behind manubrium
• Women have decreased retrosternal lucency
Three clear spaces
Three clear spaces
• Anterior clear space
• Retrocardiac clear space
– Opacification with our without discrete edge
• Anterior mediastinal mass
• Lung mass or consolidation
– Increasing lucency as progress inferiorly from
between the posterior border of heart and anterior
vertebral bodies (infrahilar)
• Decreasing
D
i width
idth off mediastinum
di ti
– Esophagus and azygous vein
– Air-filled right lower lobe (azygoesophageal
recess)
Three clear spaces
Three clear spaces
• Retrocardiac clear space
• Retrocardiac clear space
– Increasing lucency as progress inferiorly from
between the posterior border of heart and anterior
vertebral bodies (infrahilar)
• Decreasing
D
i width
idth off mediastinum
di ti
– Esophagus and azygous vein
– Air-filled right lower lobe (azygoesophageal
recess)
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Three clear spaces
– 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
Inferior hilar window
• Sub-area of retrocardiac clear space
• 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
104
– 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
Inferior hilar window
Courtesy of Robert Suh, M.D.
Courtesy of Robert Suh, M.D.
Conclusions
Inferior hilar window
• 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
Courtesy of Robert Suh, M.D.
Posttest question
References
• On a properly positioned (i.e. non-rotated) lateral
radiograph, the posterior wall of the bronchus
intermedius projects over which structure?
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.
g D. Lateral chest radiograph:
g p a systematic
y
approach.
pp
Acad Radiol
4)) Feigin
2010; 17:1560-1566.
5) Landay MJ. Anterior clear space: how clear? How often? How come?
Radiology 1994; 192:165-169.
a)
b)
c)
d)
Right upper lobe bronchus
Right hilar vascular opacity
Left main-upper lobe continuum
Left pulmonary artery
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