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Pulmonary Sequestration
Pulmonary Sequestration
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Aberrant lung tissue that
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No normal connection with the bronchial tree or with
the pulmonary arteries.
Supplied by a systemic artery (usually from the
aorta.)
Extralobar: contained within
its own viseral pleural envelope.
14~25 % of sequenstration.
Intralobar: contained within
the substance of the lung.
75~86%.
Pulmonary Sequestration
► Intralobar
sequestrations
 Two major patterns of the radiographic appearance
►A
solid-water density mass or area of consolidation.
► An air-containing single or multicystic lesion.
 The air gains entry into the sequestered lung from the collateral
ventilation.
 Infection → an air-fluid level.
 Contrast-enhanced CT and coronal MR show the
abnormal systemic artery in the majority of cases.
► Failure
to identify a systemic artery on these examinations does
not exclude the diagnosis.
 Angiography: to demonstrate the anomalous systemic
vessel.
Intralobar sequestration.
> PA radiograph: a solid mass-like lesion in the LLL abutting
the diaphragm.
> Lateral tomogram confirms a well-defined mass posteriorly
in the LLL.
Intralobar
sequestration
(air-filled).
PA radiograph:
> The pulmonary vessels
at the right base display an
abnormal course; this
suggests they may be
draped around a spaceoccupying but air-filled
lesion.
>The right hemidiaphragm
is slightly depressed, and
the heart is shifted slightly
to the left.
> Aortogram: a large single vessel arising from the distal
aorta supplying a portion of the right lower lobe.
> Contrast-enhanced CT scan confirms the vascular supply.
Pulmonary Sequestration
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Extralobar sequestration:
 Diagnosis can be made without angiography by using CT and MRI, which
may demonstrate the anomalous feeding and draining vessels.
 CXR: a single well-defined homogeneous area of increased opacity in the
lower thorax close to the posterior medial hemidiaphragm.
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no air bronchograms.
It may also occur in the mediastinum and in the pericardium or upper thorax,
and rarely as a subdiaphragmatic mass.
 Esophagrm: to demonstate the fistulous communication between the
sequestration and the GI tract.
 Aortography: to show the anomalous systemic artery or arteries feeding
the lesion.
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Demonstration of the venous drainage may require selective angiography of the
anomalous feeding vessels.
 Ultrasound: in the diagnosis of pulmonary sequestration in neonates and
infants.
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a uniformly echogenic mass with a hyperechoic rim.
Color Doppler flow imaging: aberrant arterial and venous structures supplying
and draining these lesions.
Pulmonary Sequestration
Intralobar
Extralobar
Clinical Features
Adults
M=F
Pneumonia or incidental
finding
Infants
M>F
Asymptomatic or symptoms due
to associated abnormalities
Location
60% left
Posterior lower lobe
90% left
Above or below diaphragm,
or in the mediastinum
Arterial supply
Large vessel from aorta
Single or multiple systemic
arteries
Venous drainage
Pulmonary vein
Systemic (azygos, hemiazygos,
vena cava)
Connection with
foregut
Rare
Occasionally
Pleura
No separate pleural covering Separate pleural covering
Extralobar sequestration in the RLL.
> CT scans show an abnormal systemic arterial supply (arrow) that
originates within the abdomen above the celiac artery between the
diaphragmatic crura.
> CT scans demonstrate extensive calcification (arrowheads)
at the superior aspect of the sequestrated segment. Note also
the systemic artery that enters the sequestrated segment
(arrow).
> Bedside left coronal sonogram shows a very large, fluid-filled
hemithorax with concave medial and lateral borders. A seemingly small
left lung with reverberating echoes from air is floating superiorly. The
unaerated sequestration (arrows) is present inferiorly.
> Spectral Doppler tracing of the feeding artery shows systolic peaks
with high-frequency shift and diastolic flow reversal. Two systoles were
missed due to patient motion.
> Left coronal color
Doppler sonogram reveals
the feeding artery through
unaerated sequestration (S)
arising from the left lateral
aspect of the aorta, just
below the diaphragm.
Solid arrows = thoracic aorta
open arrow = abdominal aorta
(Figure is turned 90°ckwise.)
References
► Thoracic
Radiology
THE REQUISITES 3rd Ed., Chapter 2
 T. C. McLoud et.al.
► Congenital Anomalies
of the Tracheobronchial
Tree, Lung, and Mediastinum
 RadioGraphics. 2003;24:e17
► High-Resolution CT and CT Angiography of
Peripheral Pulmonary Vascular Disorders
 RadioGraphics. 2002; 22:739–764
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