DOI:10.2214/AJR.07.2766
AJR 2008; 190:907-915
© American Roentgen Ray Society
MDCT Evaluation of Foreign Bodies and Liquid Aspiration Pneumonia in Adults
Miyoung Kim1,
Ki Yeol Lee1,
Kyung Won Lee2 and
Kyongtae T. Bae3
1 Department of Diagnostic Radiology, University of Korea Ansan Hospital, Seoul,
Korea.
2 Department of Diagnostic Radiology, University of Bundang Seoul National
University Hospital, Seoul, Korea.
3 Department of Radiology, University of Pittsburgh, 3362 Fifth Ave.,
Pittsburgh, PA 15232.
Received June 21, 2007;
accepted after revision October 17, 2007.
Address correspondence to K. T. Bae
(baek{at}upmc.edu).
CME
This article is available for CME credit. See
www.arrs.org
for more information.
Abstract
OBJECTIVE. The purpose of this article is to describe abnormalities
seen on MDCT of the airways and lung parenchyma that are caused by the
aspiration of solid foreign bodies and liquid material.
CONCLUSION. MDCT allows us to diagnose a full spectrum of disease
processes associated with aspiration and complications in the airways and
lung. Recognition of the CT findings characteristic of a specific type and
location of the aspirate is valuable to make an accurate diagnosis, thereby
facilitating optimal clinical management.
Keywords: adults • foreign bodies • liquid aspiration pneumonia • lung • MDCT • thorax
Introduction
Clinical and radiologic findings associated with foreign body aspiration in
adults have rarely been described and recognized, compared with children,
partly because the incidence of foreign body aspiration in adults is
relatively low. Foreign body aspiration in adults usually has an iatrogenic or
traumatic cause, whereas in children it is commonly self-inflicted. Although
detected radiologic findings could be readily related to foreign body
aspiration when an appropriate clinical history is available, various
nonspecific imaging features may not be easily discernable from other
disorders, causing a diagnostic dilemma. A familiarity with radiologic
features associated with foreign body aspiration is valuable to provide an
early and correct diagnosis and to determine appropriate clinical management
and intervention.
In this article, we present the MDCT findings and clinical implications of
aspiration pneumonia divided into two groups: aspiration of solid foreign
bodies such as food, teeth and dentures, wood, charcoal, vinyl, and metal; and
aspiration of liquids such as infectious material, oil, gastric acid, and
water. We also discuss underlying esophageal disease.
Aspiration of Solid Foreign Bodies to the Airways
Because foreign body aspiration in adults is not common, it may be
overlooked as a potential cause of airway obstruction. Aspiration may be
clinically silent, or patients may develop life-threatening hemoptysis as a
result [1]. The diagnosis of
foreign body aspiration may not be obvious when a patient does not remember an
episode of aspiration.
Clinical and radiologic manifestations of foreign body aspiration depend on
the size of aspirated material and the degree (partial or complete), level,
and chronicity (acute or chronic) of obstruction associated with the
aspiration. The most commonly inhaled foreign bodies are food and broken
fragments of teeth. These foreign bodies tend to lodge in the right or left
main bronchus with an equal frequency
[2,
3]. The most common symptom is
the so-called penetration syndrome, defined as a sudden onset of choking and
intractable cough, with or without vomiting. Other symptoms that occur in
isolation or in association are cough, fever, breathlessness, and wheezing
[4,
5].
Radiologic manifestations associated with foreign body aspiration into the
airways include obstructive lobar or segmental overinflation or atelectasis.
Chest radiographs are reported to show a radiopaque foreign body in
5–15% of cases [6]. CT is
far more sensitive than chest radiography in showing radiolucent foreign
bodies. In particular, CT may provide diagnostic information by showing subtle
low-attenuation intrabronchial material, which is often the only finding that
can lead to the diagnosis and identification of the level of obstruction. CT
is also more specific than radiography for characterizing the attenuation of a
suspected foreign body, which may be metallic, calcified, soft tissue, or
fatty tissue. Retained secretions may mimic foreign bodies, but they are
usually discernible by their characteristic fluidlike morphology and water
attenuation.
MDCT allows us to acquire CT images with near-isotropic data sets. In
routine clinical CT of the chest, the images are often reconstructed and
reviewed at 5-mm section thickness at standard lung and soft-tissue window
settings. When thinner sections are necessary to improve the visualization of
small foreign bodies or small airways, we can readily go back to the raw
helical CT data and reconstruct images at thinner sections. Comparison of two
sets of CT images, acquired at end-inspiration and end-expiration, may help in
accurate assessment of changes in airway dimensions and obstructive air
trapping associated with the aspiration of foreign bodies. In addition,
postprocessed CT image data, such as multiplanar reformations in various
planes and endoluminal volume-rendering techniques (i.e., virtual
bronchoscopy), depict the relationship of the finding to the airway anatomy,
which is helpful when planning removal of the foreign body.
Aspiration of a large foreign body or food particle may obstruct the
trachea and result in immediate asphyxiation
(Fig. 1) and death
[7]. When the aspirate lodges
in the main bronchus, patients may present with atelectasis (complete
obstruction) (Figs. 2A and
2B), air trapping (partial
check valve obstruction) (Figs.
3A,
3B,
3C,
3D, and
3E), or no abnormality
(incomplete obstruction) (Figs.
4A and
4B). Aspiration of a large
foreign body to the lobar bronchi may cause lobar atelectasis (complete
obstruction), air trapping (partial check valve obstruction), or
postobstructive pneumonia (Figs.
5A and
5B).
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Fig. 1 —Aspiration of bread piece in trachea of 34-year-old man with
mental retardation and abrupt dyspnea. Chest CT image (5-mm collimation, lung
window setting) after bronchoscopic removal of bread shows subcutaneous
emphysema, pneumomediastinum, and upper lung predominant consolidation in
bilateral dependent lungs. Consolidation represents additional areas of
aspiration that probably preceded tracheal aspiration.
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Fig. 2A —Aspiration of shrimp to left main bronchus during bedside
feeding in 71-year-old man with history of Parkinson's disease and abrupt
dyspnea. Contrast-enhanced CT image (mediastinal window setting) shows
endobronchial spongy soft-tissue material in left main bronchus
(arrow) and completely collapsed left lung.
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Fig. 2B —Aspiration of shrimp to left main bronchus during bedside
feeding in 71-year-old man with history of Parkinson's disease and abrupt
dyspnea. Photograph shows shrimp retrieved by bronchoscopy.
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Fig. 3A —Aspiration of tooth to right main bronchus in 43-year-old man
with dyspnea and fever. Contrast-enhanced CT images show tooth aspirated to
right main bronchus and associated atelectasis of right mid and lower
lobes.
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Fig. 3B —Aspiration of tooth to right main bronchus in 43-year-old man
with dyspnea and fever. Contrast-enhanced CT images show tooth aspirated to
right main bronchus and associated atelectasis of right mid and lower
lobes.
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Fig. 3D —Aspiration of tooth to right main bronchus in 43-year-old man
with dyspnea and fever. Oblique coronal multiplanar reformatted image shows
exact location of aspirated tooth in reference to main bronchus.
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Fig. 4A —Aspiration of clam shell to right main bronchus in
62-year-old man with blood-tinged sputum. Contrast-enhanced CT image shows
curvilinear calcific attenuation in dependent portion of right main bronchus
(arrow). No associated lung abnormality is seen. Incidental calcified
pleural plaque is present in right posteromedial thorax. Chest radiograph (not
shown) was normal.
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Fig. 5A —Aspiration of piece of wood to left lower lobar bronchus in
16-year-old boy with persistent fever after motor vehicle accident.
High-resolution CT image (2-mm collimation, lung window setting) shows large
consolidation in left lower lobe and rounded opacity in cross section
surrounded by crescent of air (arrow) in truncus basalis to basilar
segments of left lower lobe.
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Aspiration of a small foreign body or food particle obstructing the
segmental or smaller bronchi may present as an endobronchial lesion, focal
recurrent pneumonia, or focal atelectasis at a segmental or subsegmental level
(Figs. 6A,
6B, and
6C).
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Fig. 6A —Aspiration of toothpick to left lateral basal segmental
bronchus in 19-year-old man with no symptoms. Axial chest CT images (5-mm
collimation, lung [A] and mediastinal [B] window settings) show
focal bronchiectasis (arrow, A) proximal to toothpick
(arrow, B) in lateral basal segmental bronchus of left lower
lobe. Chest radiograph (not shown) was normal.
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Fig. 6B —Aspiration of toothpick to left lateral basal segmental
bronchus in 19-year-old man with no symptoms. Axial chest CT images (5-mm
collimation, lung [A] and mediastinal [B] window settings) show
focal bronchiectasis (arrow, A) proximal to toothpick
(arrow, B) in lateral basal segmental bronchus of left lower
lobe. Chest radiograph (not shown) was normal.
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Fig. 6C —Aspiration of toothpick to left lateral basal segmental
bronchus in 19-year-old man with no symptoms. Coronal reformatted CT image
(mediastinal window setting) shows linear endobronchial lesion
(arrow) in lateral basal segmental bronchus of left lower lobe.
Bronchoscopic evaluation confirmed segmental bronchiectasis, and wooden
material with mucus impaction was retrieved.
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Late complications related to aspiration of foreign bodies are
bronchiectasis (Figs. 6A,
6B, and
6C), bronchial stricture,
massive hemoptysis, inflammatory granulation tissue or mass at the site of
lodgment, or recurrent pneumonia. Accurate diagnosis requires a careful review
of radiologic findings and integration of radiologic and clinical data.
Aspiration of Liquid Materials
Clinical and radiologic manifestations of liquid aspiration depend on the
volume, pH, and chronicity (acute, chronic, or recurrent) of aspirated
material and underlying abnormalities of the esophagus or tracheobronchial
tree. A lobar or segmental distribution is often seen with aspiration.
Posterior segments of the upper lobes and superior segments of the lower lobes
are frequently involved when patients aspirate while in the recumbent
position, whereas the bibasilar segments, right middle lobe, and lingular
segment are affected in erect patients.
Gastric Acid (Mendelson's Syndrome)
Gastric acid with a pH greater than 2.5 can cause pathologic reactions
ranging from mild bronchiolitis to hemorrhagic pulmonary edema. Acid liquid
introduced into the airways tends to disseminate rapidly into the bronchial
tree and lung parenchyma, resulting in chemical pneumonitis and the formation
of extensive consolidation within minutes
[7] (Figs.
7A and
7B).
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Fig. 7A —Aspiration of gastric acid to bilateral dependent lungs in
60-year-old man with fever and loss of consciousness. Chest CT images (2-mm
collimation, lung window setting) show extensive bilateral airspace
consolidation, mainly in dependent portions of lungs.
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Fig. 7B —Aspiration of gastric acid to bilateral dependent lungs in
60-year-old man with fever and loss of consciousness. Chest CT images (2-mm
collimation, lung window setting) show extensive bilateral airspace
consolidation, mainly in dependent portions of lungs.
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Near-Drowning
In near-drowning, defined as severe asphyxia caused by submersion in water
but not resulting in death, chemical and organic contaminants in the aspirated
water are thought to cause adult respiratory distress syndrome. The
radiographic features and clinical course of the aspiration of fresh water are
not much different from those of salt water. Radiographic findings are often
presented as scattered ground-glass opacities that progress to patchy airspace
consolidation over the next several days
[7] (Figs.
8A and
8B). Ground-glass opacities
and consolidation likely represent pulmonary edema and adult respiratory
distress syndrome, largely secondary to fluid entering the alveoli from the
blood or disruption of the surfactant production. Common occurrences of
high-attenuation sediment or frothy dependent materials in the airways have
been reported in near-drowning and drowning victims.
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Fig. 8A —Near-drowning in fresh water in 34-year-old woman with
history of schizophrenia and dyspnea. High-resolution CT image (2-mm
collimation) obtained 2 days after incident shows consolidation in posterior
upper lobes. Surrounding ground-glass opacity likely reflects exudative stage
of adult respiratory distress syndrome.
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Fig. 8B —Near-drowning in fresh water in 34-year-old woman with
history of schizophrenia and dyspnea. Follow-up high-resolution chest CT image
(2-mm collimation) 9 days later shows development of volume contractile
consolidation, probably representing proliferative stage of adult respiratory
distress syndrome.
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Chronic Exogenous Lipoid Pneumonia
Repeated small aspiration or inhalation of mineral oil (paraffin, kerosene,
or petroleum jelly), fish oil (squalene), and vegetable oil can lead to
exogenous lipoid pneumonia. CT is the technique of choice in establishing the
diagnosis of lipoid pneumonia, typically showing lipid attenuation in the
consolidated lung [8]. The
crazy-paving pattern has been described on thin-section MDCT in some cases of
exogenous lipoid pneumonia [8]
(Figs. 9A and
9B). Lipoid pneumonia is
frequently seen in the right middle lobe.
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Fig. 9A —Chronic exogenous lipoid pneumonia in 50-year-old man with
history of taking fish oil (squalene) tablets for 6 months and multiple
episodes of aspiration but no symptoms. High-resolution CT images (2-mm
collimation, lung window setting) show geographic ground-glass opacity with
superimposed intra- and interlobular septal thickening in right middle
lobe—that is, characteristic crazy-paving pattern and lobular
consolidation. Faint mild alveolar infiltrates are also present in right lower
lobe.
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Fig. 9B —Chronic exogenous lipoid pneumonia in 50-year-old man with
history of taking fish oil (squalene) tablets for 6 months and multiple
episodes of aspiration but no symptoms. High-resolution CT images (2-mm
collimation, lung window setting) show geographic ground-glass opacity with
superimposed intra- and interlobular septal thickening in right middle
lobe—that is, characteristic crazy-paving pattern and lobular
consolidation. Faint mild alveolar infiltrates are also present in right lower
lobe.
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Acute Exogenous Lipoid Pneumonia ("Fire-Eater's Pneumonia")
Aspiration of a large amount of liquid paraffin and petroleum may lead to
an acute and fatal form of exogenous lipoid pneumonia. Acute pneumonitis after
aspiration of petroleum is usually related to accidental poisoning in
fire-eaters. These patients are usually quite ill at presentation and may
succumb to progressive respiratory failure. This form of mineral oil
aspiration is quite rare but can be readily diagnosed on CT because of the
characteristic attenuation of aspirated substance in the range of lipid
attenuation [7] (Figs.
10 and
11).
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Fig. 10 —Acute exogenous lipoid pneumonia in 23-year-old man with
accidental aspiration of kerosene and chest discomfort. CT image (5-mm
collimation, lung window setting) shows area of well-defined consolidation and
ground-glass opacities in right middle lobe.
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Fig. 11 —Acute exogenous lipoid pneumonia in 38-year-old man with
acute accidental aspiration of paraffin oil and chest discomfort.
Contrast-enhanced CT image shows areas of well-defined consolidation, small
area of fat attenuation (-40 H) (arrow), and air bronchograms in
right middle and left lower lobes.
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Infectious Material from the Oropharynx
Patients with poor oral hygiene and advanced periodontal disease are at
high risk of developing infection after aspiration. In non-hospitalized
patients, the normal flora of the oropharynx are low-virulence commensal
organisms, such as Actinomyces israelii
(Fig. 12) and a variety of
anaerobic bacteria, such as Bacteroides and
Peptostreptococcus species
[7]. Aspiration of infectious
material may result in a consolidation or abscess in a lobar distribution.
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Fig. 12 —Aspiration of infectious material from oropharynx to
posterior segment of right upper lobe in 40-year-old man with periodontal
disease, actinomycosis, and low-grade fever. Contrast-enhanced CT image shows
peripheral focal consolidation and internal necrosis, suggesting abscess
formation.
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Concomitant Esophageal Disease
Patients with concomitant esophageal abnormalities such as achalasia (Figs.
13A and
13B), esophagorespiratory
fistula (Figs. 14A,
14B,
15A, and
15B), esophageal diverticulum,
hiatal hernia, gastroesophageal reflux, and esophageal stricture or malignancy
may recurrently aspirate small quantities of acid, food, or lipid. If
unrecognized and untreated, recurrent aspiration may result in chronic or
recurrent pneumonia, pulmonary fibrosis (Figs.
14A and
14B), and, occasionally,
complete lung destruction
[2].
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Fig. 13A —Pyogenic lung abscess from aspiration in 65-year-old woman
with history of achalasia, cough, fever, and sputum. Contrast-enhanced CT
image (mediastinal window setting) shows large solid mass with necrosis in
right upper and lower lobes. Esophagus is dilated and esophageal wall is
mildly thickened.
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Fig. 13B —Pyogenic lung abscess from aspiration in 65-year-old woman
with history of achalasia, cough, fever, and sputum. Esophagography shows
diffusely dilated esophagus with distal beak appearance, consistent with
achalasia. Although bronchogenic carcinoma was suspected clinically, chronic
pyogenic lung abscess was diagnosed at transbronchial biopsy.
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Fig. 14A —Aspiration through bronchoesophageal fistula in 82-year-old
man with history of radiation therapy for esophageal carcinoma, persistent
cough, and sputum. Contrast-enhanced chest CT image shows fistula
(arrow) between esophagus and left main bronchus.
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Fig. 14B —Aspiration through bronchoesophageal fistula in 82-year-old
man with history of radiation therapy for esophageal carcinoma, persistent
cough, and sputum. High-resolution CT image (2-mm collimation) shows multiple
patchy, irregular parenchymal areas of increased attenuation in both
lungs.
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Fig. 15A —Pyogenic lung abscess from aspiration of gastric fluid
through esophagopulmonary fistula in 55-year-old man with fever.
Contrast-enhanced CT image (mediastinal window setting) shows
esophagopulmonary fistula (arrow) and consolidation with necrosis in
right lower lobe.
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Fig. 15B —Pyogenic lung abscess from aspiration of gastric fluid
through esophagopulmonary fistula in 55-year-old man with fever. CT image
(5-mm collimation, lung window setting) shows consolidation and cavitary
abscess in right lower lobe and focal pneumonic infiltrate in left upper
lobe.
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Conclusion
MDCT allows the diagnosis of a full spectrum of disease processes
associated with the aspiration of solid and liquid foreign bodies and
associated complications in the airways and lung parenchyma. MDCT improves the
specificity of diagnosing aspiration-related findings that often appear
nonspecific on chest radiography. Recognition of CT findings characteristic of
a specific type and location of the aspirate is valuable for making a prompt,
accurate diagnosis, thereby facilitating optimal clinical management and
intervention.
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Abstract
Introduction
