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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5769_Библиотеки_им_академика_М_И_Перельмана
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190 oracic ultrasound
e interstitial pathology is expressed with the interstitial syndrome, characterized by the
presence of B Lines and/or white lung (Fig. 33) (Clip 23).
HYPERECHOIC SPOTS
Figure 32 – Inflammatory consolidation with hyperechoic spots, that are the expression of air trapped
in the bronchioles.
Figure 33 – Interstitial pneumonia with numerous B Lines.
Clip 23 – Interstitial pneumonia. Ultrasound shows the presence of numerous
and coalescing B Lines. This case is similar to acute pulmonary edema or the
early stage of ARDS.
B LINES
Parenchymal lung patology 191
Radiological reticular, nodular or mixed opacities have no echographic equivalent, except
the evidence of a more or less dense interstitial syndrome, unless nodules of appropriate size
reach the pleura.
However, experience shows that CT ground glass appears in echography as a field rich in
dense B Lines, converging to areas of white lung92. On the other hand, ultrasound of a consolidation is able to demonstrate a radio occult finding that is the fluid bronchogram. It is
the appearance of bronchi and bronchioles filled with fluid, creating the picture of transonic
tubules parallel to the vessels.
As previously mentioned, the presence of fluid bronchograms means an obstructive origin
of the consolidation.
➣ Pneumonias
Pneumonias are infections of the alveolar portions (dedicated to gas exchange) of the lungs.
Pneumonias can be divided into
• community-acquired pneumonia
• nosocomial pneumonia
• pneumonia related to mechanical ventilation
• Health care associated pneumonia (Tab. 12).
Table 12 – Epidemiological classification of pneumonia and diagnostic criteria
93-95
:
Classification Criteria
Community-acquired
pneumonia
Nosocomial pneumonia Pneumonia that occurs after hospitalization (48 hours or more)
Pneumonia related to
mechanical ventilation
Health care associated
pneumonia
Pneumonia in non-hospitalized subjects within the previous
14 days
Pneumonia that occurs after tracheal intubation (48 or more
hours)
Patients hospitalized for 2 days or more in the previous 90 days
Patients admitted to medical or social institutions
Patients subjects to intravenous antibiotic therapy at home
Dialysis patients
Subjects with chronic ulcers
Subjects receiving chemotherapy
Immunocompromised subjects
Anatomically, pneumonias are classified into:
• Lobar pneumonia: When the alveolar edema is followed by leukocyte migration with
a consolidation of one or more lobes. Exudate spreads toward the hilum crossing the
segmental boundaries, limited by the fissures (e.g. Streptococcus pneumoniae pneumonia).
• Bronchopneumonia (anatomically lobular pneumonia): in which the exudative inflam-
matory process tends to be confined by the interlobular septa, clinically manifested with
parenchymal or patchy consolidation (e.g. Staphylococcus pneumonia).
• Acute interstitial pneumonia: produced by viruses and mycoplasma, in which the
alveolar exudate, if present, is not as marked or confluent as in lobar pneumonia or
bronchopneumonia.
192 oracic ultrasound
• Mixed pneumonia: with a combination of lobar, interstitial and broncho-pulmonary
inflammation.
Acute pulmonary infections are produced by a variety of etiologic agents and are cause of
high morbidity and mortality, especially in the elderly and in immunocompromised patients.
Table 13 summarizes the causes of pneumonia. However, in a percentage between 15% and
35% of cases, the etiology is never identified.
e most frequent pneumonias are pneumococcal, followed by viruses, Mycoplasma, Legionella
and Chlamidophila. Streptococcus pneumoniae and Legionella cause the most severe forms of
community-acquired pneumonia. Multiple bacterial pathogens are responsible of up to 5%
of the pneumonia95.
Table 13 – Causative agents in pneumonia
Community-acquired pneumonia
Streptococcus pneumoniae (lobar or lobular pneumonia) (50-65%)
Haemophilus influenzae (4-8%)
Staphylococcus aureus (< 5%)
Streptococcus pyogenes
Gram-negative bacteria or anaerobes (mainly in aspiration syndromes and in patients with some
immunodeficiency)
Tuberculosis
Virus (herpes, influenza, chickenpox, rubella etc.)
Nosocomial pneumonia
Gram-negative bacteria (Proteus vulgaris, Escherichia coli, Enterobacter spp., Salmonella spp.,
Klebsiella)
Anaerobes (Bacteroides fragilis, B. melaninogenicus, B. oralis, Fusobacterium, Clostridium spp. ecc.)
Pseudomonas aeruginosa (particularly in subjects undergoing ventilation)
“Atypical” pneumonia
Mycoplasma pneumoniae (10-20%, 50% of pneumonia in less than 16-year-old subjects)
Legionella pneumophila (< 8%)
Chlamydia spp.
Coxiella burnetii
Virus (adenovirus, parainfluenza virus, VRS etc.)
Pneumonia in immunocompromised subjects
All of the above
Pneumocystis carinii
Miceti (Cryptococcus, Histoplasma, Aspergillus, Candida)
Rhodococcus equi o Nocardia spp.
Toxoplasma
Mycobacteria
Virus (citomegalovirus, VRS, adenovirus)
Parenchymal lung patology 193
In ultrasound, we can separate alveolar (consolidative), interstitial or mixed pneumonia,
employing an anatomical classification, as with CT. e acoustic behavior of the pneumonia
helps in this distinction.
Lobar pneumonia is a consolidation that affects an entire lobe and has clear boundaries
represented by the fissures.
Interstitial pneumonia appears as a focal area in which there is an evident interstitial syndrome,
ranging from dense B Lines to white lung96.
Mixed pneumonia (typically bronchopneumonia) show lung patterns ranging from small
foci of subpleural consolidation, to more or less large consolidations with irregular or blurred
margins, surrounded by regions with interstitial disease also multiple, to areas of compact
interstitial syndrome.
Although sufficiently precise in terms of localization and appearance, ultrasound, like the chest
X-ray, is little specific about the etiology of the infection, although some aspects exemplified
in Table 14 may help.
Table 14 – Radiographic features of pneumonia and its causative agent
Microrganism Radiographic features
Streptococcus
pneumoniae
Staphilococcus
aureus
Klebsiella
pneumoniae
Pseudomonas
aeruginosa
Haemophilus
influenzae
Legionella
pneumophila
Moraxella catarralis Diffuse infiltrates
Chlamidophila
pneumoniae
Mycoplasma
pneumoniae
Anaerobic germs Consolidations of sloping parts of the lungs with a tendency to abscess
Consolidation, occasional pleural effusions
Patchy, multilobar infiltrates, abscess, empyema
Consolidation of superior lobes, volume increase with bulging fissures,
abscesses
Patchy infiltrates with frequent abscess
Mainly basal patchy infiltrates, occasional pleural effusions
Multiple non-segmental patchy infiltrates, tending to consolidation,
cavitations and occasional pleural effusions
Patchy infiltrates
Interstitial infiltrates (nodular pattern), patchy density, occasional
consolidations
In ultrasound, pneumonia is seen as a more or less confined consolidation, in which the
mirror effect of a normally aerated lung is lost
97-98
.
e consolidated area is hypoechoic, with a liver like texture. Its feature varies depending
on its extent and from scissural or segmental limitations. e shape ranges from triangular
pleural based configurations, to morphologies characterized by irregular and poorly defined
boundaries. Where the whole lobe is not involved, pneumonia generally maintain a segmental
aspect. Its echogenicity is inhomogeneous, as air bronchograms (present in about 80-90% of
79,97,98
cases)
or hyperechoic spots due to trapped air in the bronchioles, may appear inside it.
194 oracic ultrasound
Transonic tubular structures that represent the vessels are easily detectable through B-Mode
ultrasound and color Doppler. ese tubular structures with echogenic walls and without
flow represent bronchi filled with liquid (fluid bronchograms), typical of post-obstructive
pneumonia (Fig. 34) (Clip 24).
Fluid bronchograms
Figure 34 – Post-obstructive pneumonia in 8-year-old child. Inside the consolidation anechoic tubular
structures with hyperechoic wall are evident, they are bronchial tubes filled with fluid (fluid bronchograms).
Clip 24 – In the pediatric age, pneumonias are frequently post-obstructive.
Often the obstruction is caused by mucus plugs. Consolidation with
hyperechoic spots due to trapped air in the bronchioles and numerous
anechoic structures due to fluid bronchograms.
Involving the pleural surface, the consolidation produces a typical interruption of the superficial hyperechoic band (surface alveologram), which ends at the edge of the lesion. Where the
lung is consolidated, pleural sliding it is very low or absent
97-100
. Behind the consolidation, the
relatively healthy lung often shows a characteristic echogenic enhancement. is phenomenon
is due to an abrupt transition from the consolidated area (with a high fluid content) to the
posterior aerated lung, and it is the equivalent of the posterior wall enhancement typical of
the fluid filled cysts (Figs. 35-38) (Clips 25-28).
Clip 25 – Pneumonia: dynamic air bronchograms during mechanical
ventilation.
Clip 26 – Pneumonia of the left inferior lobe. The lung shows spleen-like
ecogenicity. A mild pleural effusion is observed.
Parenchymal lung patology 195
Clip
27 – Left basal pneumonia with moderate pleural effusion.
Clip 28 – Pneumonia. Numerous B Lines around the consolidation.
HYPOECHOIC PLEURAL LINE
PNEUMONIA
Figure 35 – Pneumonia: reduction in the echogenicity of the pleural line at consolidation level.
PNEUMONIA
AIR BRONCHOGRAMS
Figure 36 – Pneumonia: extended hepatized area with air bronchograms.
196 oracic ultrasound
ECHOGENIC ENHANCEMENT
Figure 37 – Pneumonia: increase in the echogenicity behind pneumonia.
PNEUMONIA
Figure 38 – Pneumonia: irregular hypoechoic area with pleural line interruption.
In a fair number of cases there is also a pleural effusion, often of small size, and is therefore
not detected by chest X-ray (Figs. 39-40).
In some cases, the hypoechogenicity of a pulmonary consolidation merges with that of the effusion. In these situations, the search for the sinusoid sign, the fluid color sign, and the injection
of ultrasound contrast media, is useful to distinguish them (see chapter on pleural effusions)
100
.
Parenchymal lung patology 197
PNEUMONIA
PLEURAL EFFUSION
Figure 39 – Extended right basal pneumonia. Evidence of a small pleural effusion above the diaphragm.
PLEURAL EFFUSION
LIVER
PNEUMONIA
Figure 40 – Right basal pneumonia with pleural effusion.
Often, in echography the consolidation appears smaller than what is seen in chest X-ray.
Probably this is the consequence of a limited evaluation of the sonographer, who does not
consider the involved parenchyma, including the surrounding interstitial syndrome. e
interstitial syndrome around a consolidated core, detected by x-ray, is always evident as white
lung and coalescing B Lines. (Fig. 41) (Clip 29).
198 oracic ultrasound
Figure 41 – Right bronchopneumonia. To the left: X-ray image. The ultrasound scans (right and bottom)
highlight irregular alveolar consolidation (top) and the adjacent interstitial syndrome (bottom) from
inflammatory edema.
Clip 29 – The respiratory excursions reveal the presence of an extensive
pulmonary consolidation and numerous contiguous B Lines.
Much more frequently it is the chest X-ray that underestimates the presence of pneumonia.
In a study involving 49 subjects in an emergency department with a clinical suspicion of
pneumonia, Parlamento and coll.97 showed echographic evidence of consolidation in 96.9%
of them. Chest X-ray discovered pneumonia in 75% of cases. In this study, CT represented
the gold standard. A more recent publication showed comparable data and an ultrasound
sensitivity of 96%98.
In adults, consolidations would reach the pleural line, thus being visible to ultrasound examination in approximately 98.5% of cases
100
. In our experience, all pneumonias studied
with CT reach at some point the pleural line. is means that virtually all of them can be
viewed by ultrasound.
As the pulmonary lesion is often small, a careful search on all lung surfaces is obviously necessary. A “sentinel” white lung is often helpful in addressing scans. is reminds of the presence
of frequently hidden areas in the lungs.
A good sign that induces looking for lung consolidation is the presence of an area of interstitial syndrome or the finding of pleural fluid. Sometimes a scissural effusion reveals a small
consolidating lesion inside a fissure.
Parenchymal lung patology 199
In the later stages, complications of a consolidation may be obvious. Unfavorable development may progress to an obstructive bronchial syndrome or abscess
101
. Conversely, ultrasound
captures early signs of improvement.
A pathologic bronchus feeding a consolidation progresses to complete obstruction for secre-
tion, exudate or an enlarging tumor. In any case the complete resorption of the air in the
lesion occurs. the consolidation becomes perfectly solid, sometimes with evidence of fluid
bronchograms.
In the context of a consolidation, the appearance of hypoechoic or cyst-like rounded areas
inside a consolidation is not uncommon (Fig. 42) (Clip 30), and is due to the formation of
microabscesses. However a large abscess develops rarely (6% of cases).
PLEURAL EFFUSION
MICROABSCESSES
Figure 42 – Evidence of microabscesses (arrows) in the context of a lung consolidation. Slight pleural
effusion.
Clip 30 – Case of Figure 42.
In the case of a significant abscess, a fluid collection is observed. It consists of a central
cavity with variably echogenic content. e fluid can be transonic, corpuscular, pseudosolid or contain gas, that is represented by echogenic foci
101
.
Over time, the surrounding walls become thicker and more echogenic, in relation to the
formation of fibrous tissue encapsulating the colliquation (Figs. 43-47).
In the healing phase of a pneumonic consolidation air bronchograms increase and the
appearance of dynamic air bronchograms can be observed. Air then gradually reaches the
periphery of the pneumonia, restoring the artifactual appearance of the focal interstitial
syndrome. However, a small blurred consolidation can remains for 20 days or more
(Figs. 48-49).
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