Ultrasonography is a non-invasive imaging technique that uses high frequency sound waves to visualize structures in the body. It is useful for evaluating the lungs and pleural spaces. Key findings on ultrasound relevant to the lungs include: the presence of lung sliding, A-lines, B-lines indicating interstitial edema, consolidations, and pleural effusions. Ultrasound can detect even small pleural effusions and help characterize their nature. It is a valuable tool for guiding procedures like thoracentesis. Compared to chest x-rays and CT scans, ultrasound offers advantages of being portable, avoiding radiation exposure, and allowing real-time imaging at the bedside.

1. Dr Soumitra Mondal
2nd Year PGT
Dept. Of Respiratory Medicine
Medical College Hospital, Kolkata

2.  Ultrasonography is a Non-invasive procedure
for visualising soft tissue structures of the
body by recording the reflection of non
audible# sound energy directed into the
tissues.
 Normal Human hearing frequency :
20Hz to 20000 Hz(20 kHz) .
 # For USG : 2 – 20 MHz used.(1000 times
greater) .
 For thorax mostly – 3.5 to 5 MHz

3.  Monitor
 Console
 Transducer

4.  Curvilinear Probe : Low to medium frequency
probe. Used for thoracic and abdominal
applications .
 Linear probe : High frequency . For vascular
structures .
 Phased array probe .
 Cardiac Probe : For Echocardiography .
 Endo – cavity probe.

5.  Transducer is a device that can convert one
form of energy into another and acts as both
transmitter and receiver .[pulse-echo]
 A thin piezoelectric crystal is used.
 High frequency – High resolution.
>5 MHz low penetration.
shallow structures.
 Low frequency - Less resolution.
<5 MHz greater penetration.
deeper structures .

6.  Anechoic :
~ No returning echoes = black(acellular fluid)
 Echogenic :
~ due to returning echoes, some shade of grey
a. Hypoechoic
b. Isoechoic
c. Hyperechoic .
 Solid structures : Acoustic shadow .
 Air bubbles : strongly reflecting all echos.

7.  A mode : Amplitude Mode
 B mode : Brightness Mode
 M mode : Motion Mode
 Others :
 Colour Doppler
 Duplex scan
 3D & 4D Imaging

8.  Performed with the patient in seated position.
Patients who are critically ill may be examined
in the supine or lateral decubitus position.
 Arms should be abducted.
 After applying of coupling gel and application of
firm pressure on the transducer which is applied
perpendicular to the skin and adjusted to scan
intercostal spaces longitudinally.
 Superficial structures will be at the upper part of
the screen and deep structures at the bottom.
 for better image acquisition depth and gain to
be adjusted.

10.  Several basic findings are central to the
diagnostic application to lung pathology.
I. Lung sliding
II. A line
III. B line
IV. Z line
V. Lung pulse
VI. Consolidations
VII. Seashore sign
VIII. Others

11.  This is shimmering to and fro movement of
pleural line( 5 mm below skin and
hyperechoic line) with respiration.

12.  A LINE are one or more
horizontally oriented
lines visible deep to the
pleural line.
 They are always
separated by same
distance.
 Reverberation of pleural
line.
 Present in normal lung.

13.  Also known as comet tail sign.
 They are vertical in orientation and hyperechoic.
 Originate at the pleural line.
 They extend to the bottom of the screen.
 They efface ‘A LINES’ at the intersect.
 Correlates with an interstitial edema.
 For alveolar intestinal pattern, at least 3 B-
LINES in one intercostal space in atleast 2
scanning zones required.
 1-2 B-Lines may present normal individual.
 Presence of B-Lines rules out pneumothorax.

14. B LINE and COMPARISON BETWEEN A
LINE AND B LINE.
Also showing BAT sign formed due to
RIBs.

15.  An artifact of B- Line.
 Randomly found any part of lung.(so not
always arise from pleura.)
 Less echoic
 Ill defined
 Vanishing after 2-4 cm
 Do not move with lung sliding.
 They do not efface ‘A LINES’ at the intersect.
 Seen in healthy subject
 Also seen in pneumothorax.

16. ‘O’ LINES
 Absence of A line.
 Due to fault in probe handeling.
‘I’ LINES (Inflammatory)
 Short lines arise at pleura.
 Fade as run deeper.
 Seen with high frequency (10MHz) probe.
 More seen in old age with increase
inflammation or fibrosis.

18.  Are board.
 Hyperechoic stripes.
 Runs perpendicular to pleura and originate
from pleural line.
 Highly specific for pneumonia without
parenchymal consolidation.

20.  Manifest as tissue density, its echogenecity is
similar to that of liver.
 May be localised to a specefic lob or segment
of lung.
 With consolidation punctate hyperechoic foci
(air bronchogram) are often visible.
 Sometimes consolidated lung tissue appears
as a subpleural hypoechoic region that has an
irregular (Shredded) deep border (fractal
line) abutting normally aerated lung,which
has echogenic artifacts. Known as SHRED
SIGN or FRACTAL SIGN.

22.  Generated by subcutaneous emphysema.
 Vertical laser like line.
 Reach the edge of the screen.
 Do not arise from the pleural line.
 Associated with specific feeling during
pressing the transducer.

23.  This is a M Mode view of
normal lung.
 This image demonstrates a
linear pattern in the tissue
superficial to the pleural
line and granular or sandy
appearance deep to the
pleural line.
 Indicates normal lung sliding
and excluding
pneumothorax.

24.  This M Mode image
demonstrates a linear,
laminar pattern in the tissue
both superficial and deep to
the pleural line.
 This is also known as
STRATOSPHERE sign.
 This indicates absent lung
sliding and suggests
pneumothorax.

25.  This M Mode image
demonstrates an
alternating pattern of
absent lung sliding with
normal lung sliding.
 This occurs at the
boundary of the
pneumothorax.
 Known as lung point.
 Confirms presence of
pneumothorax.

27.  The lung pulse refers to the subtle rhythmic
movement of the visceral upon the parietal
pleura with cardiac oscillations.
 If a normal subject suspends respiration, lung
sliding is temporary absent but lung pulse will
be present.
 When pulse present
There is no
pneumothorax
at the site of
Examination.

29.  Ultrasonography is particularly effective for
identifying pleural fluid .
 Pleural fluid as small as 5 ml can be
identified.
 Usg is more sensitive than chest radiography
in distinguishing effusions from pleural
thickening or lung atelectasis.
 It can also helps in diagnosis of various
pleural pathology.

30.  Pleural fluid is either anechoic or hypoechoic
relative to adjacent soft tissue.
 Recognition of the diaphragmatic pleura
through liver or spleen is required to identify
free fluid in the pleura along with atelectatic
lung in bottom and chest wall superficialy.
This is known as STATIC Sign.
 DYNAMIC Sign : this signs can help avoid
misdiagnosis includes the movement of
atelectatic lung visualised as a flapping or
floating within the effusion. This also known
as JELLYFISH Sign.

32.  In addition sometimes on B-Mode a
curtain of areated(expanded) lung
slides into and out of small effusions
known as CURTAIN Sign.
 On M-Mode this makes a sinus wave(or
sinusoidal pattern) by respiratory
movement of the visceral pleura
toward chest wall.Known as SINUSOID
SIGN.
 Sinusoid sign allows not only full
confidence in the diagnosis of pleural
effusion (with QUAD Sign), but also
indicates possibility of using small
needle for withdrawing fluid.

33.  Characterization of pleural fluid is
based on echogenicity and
homogeneity.
 In heterogeneous effusions the
presence of internal echoes such as
swirling debris or septations is
highly predictive of either
complicated parapneumonic
effusion or malignancy.
 In immobile patients the cellular
components may settle to create a
bilayer with a more echogenic
dependent component,termed as
HEMATOCRIT Sign. On movement
they create PLANKTON Sign. They
can be seen in either hemothorax or
empyema.

34.  For this higher frequency probe
is used.
 Pleural thickening >10 mm with
nodularity, frond like protrusions found to be
highly suggestive of a malignant effusion.
 Pleural thickening with unclear and irregular
border, nodularity, and evidence of chest
wall or diaphragmatic invasion is indicative
of malignant mesothelioma.(shown in image)

35.  In the diagnosis of pleural effusion. It can identify even
if only 5-10 ml fluid is present. Slide 39
 To differentiating a pleural effusion from pleural
thickening or atelectasis.
 To semi quantify the amount of fluid. Formula :
volume(ml) = 20 x the separation of visceral and
parietal pleura (in mm). Slide 40
 To characterising type of fluid.(transu vs exudative)
 To identify presence of septations( in complicated
effusions or empyema)
 To identify etiology of fluid.(malignant or benign)
 To diagnose pneumothorax.
 Identification of solid pleural lesions and pleural
thickening.
 It can identify and differentiate between lung
consolidation , pulmonary edema and ARDS.

36.  To perform thoracentesis and identifying safe site
for needle insertion.
 To identify safe site for chest tube insertion in
pneumothorx or empyema.
 To guide transthoracic intervention.(like pleural
biopsy, chest wall mass biopsy or lung biopsy)
 To rule out complications like pneumothorax
after bronchoscopy or thoracentesis.
 To check wheather lung is expanded after pleural
drain.
 Also useful in assessing diaphragmatic function.
 In follow up of community acquired pneumonia.
 May be useful in evaluation of dyspnoea in the
critical care setting.(the BLUE protocol)
 In the diagnosis of pulmonary embolism.

37.  Safe (No risk of radiation)
 Portable and bed side
 Repeatable
 Digital and multiple use
 Cost effective
 Real time
 No documented side effect
 Rapid
 Painless

38.  Heavily operator dependent.
 Limited or no documentation of the results
so limiting serial or retrospective analysis of
previously acquired images.
 no global picture
 Cannot determine exact position of devices
 Image quality is reduced in patients with
obesity, oedema or emphysema.
 Focal abnormality surrounded by aerated
lung like SPN will no be visible
 Mediastinal structures are not visible.

41. For comparison,
To detect pleural effusion,
 Normal - 5 ml
 Usg – 5-10 ml
 Ct scan -10 ml
 Lateral decubitus CXR – 10 ml
 In lateral view CXR – 50 ml
 Minimum fluid to obliterate cp angle(PA ) – 175 ml
 In CXR (PA VIEW) – 200-250 ml
 In CXR (supine) - atleast 300 ml
 For obscuring entire hemidiaphragm (in PA view) –
500 ml
In lat decu CXR fluid thickness 30mm = 1000ml
In USG 40 mm = 1000ml Application

42. For quantify,
In CXR (PA) –
 NON –MASSIVE- Opacity(fluid) upto lower border of
anterior part of 2nd RiB.
 MASSIVE – Cross the 2nd rib
In ACCP parapneumonic,
 SMALL EFFUSION : <10mm in thickness on
decubitus CXR, USG or CT scan.
 Moderate : >10mm and < ½ hemithorax(PA)
 Large : > ½ hemithorax
Effusions < 1 cm on lat decu CXR = <300ml fluid and
contraindicated for thoracentesis. Application

43. lights, book,
 Small-: <1.5 cm on lateral decubitus
 Moderate : 1.5 – 4.5 cm on lat decu cxr
 Large : > 4.5cm
Thorax.bmj,
 Small : <500ml
 Moderate size –: 500-1000 ml
 Large : >1000ml
Also,size estimated by method of counting
intercostal spaces (ICS) from costophrenic angle:
 Small : localised to 1 ICS,
 Medium : 2-3 ICS
 Large : =/> 4 ICS

44. As NCBI.nlm.nih.com
In CT Scan,
 Small – AP depth <3.0 cm
 Moderate 3-10 cm
 Large >10 cm
Also,
Effussions occupying in CT,
 Small : < 1/3 of hemithorax
 Moderate : between 1/3 to 2/3
 Large : more than >2/3 of hemithorax.
Application