ebus

1. Endobronchial Ultrasound
Dr. Rikn Hasnani

2. Introduction
• Endobronchial ultrasonography (EBUS) is a diagnostic modality in
which a miniature ultrasonic probe is introduced into the
tracheobronchial lumen to provide the sonographic images of the
peribronchial tissue.
• Currently, there are three EBUS probes available for different
applications:
• (1) Ultraminiature radial probes (20 and 30 MHz) – for peripheral
lesions ,
• (2) radial balloon probes (20 MHz) – for larger airways , and
• (3) convex probe or curvilinear EBUS (CP-EBUS).

3. Scientific basis of ultrasound
• Piezoelectric effect
• Depth penetration depends on
• 1. frequency and
• 2. transducer size
• Depth penetration increases as
frequency decreases and size of
transducer increases .

4. Clinical Applications
• (a) determination of the depth of tumor invasion of the tracheal/ bronchial
wall,
• (b) analysis of the structure of the bronchial wall for airway diseases such
as tracheobronchomalacia,
• (c) identification of the location of a peripheral lung lesion during
bronchoscopic examination. Radial probe EBUS is more accurate than
fluoroscopy in determining contact between lesion and bronchus.
Therefore it reduces the time to determine the biopsy sites and the
duration of fluoroscopy,
• (d) qualitative analysis of peripheral lung lesions to differentiate between
benign and malignant lesions,
• (e) guidance for transbronchial needle aspiration-radial probe EBUS is
largely replaced by convex-probe EBUS for this indication.

5. Equipment
• A 20 MHz mechanical radial ultrasonic probe with a balloon- tip
sheath is used, that can be introduced through the 2.8 mm diameter
working channel of a flexible bronchoscope .
• These probes are connected with the Endoscopic Ultrasound System
to obtain EBUS images.

6. Performing EBUS Using a Balloon Probe
• The balloon probe is inserted into the working channel of the
bronchoscope, advanced beyond the lesion, and then inflated with
the minimum amount of saline required to obtain an EBUS image of
the entire circumference of the bronchial wall.
• Scanning is performed while retracting the probe slowly.
• Advancing the probe from proximal to distal airways can cause
damage to the probe, and should be avoided.
• Using a 20 MHz probe, five layers can be identified on ultrasound
images of the cartilaginous portion of extrapulmonary and
intrapulmonary bronchi.

7. • The first layer (hyperechoic) is a marginal echo,
• the second layer (hypoechoic) represents submucosal tissue,
• the third layer (hyperechoic) is the marginal echo on the inner aspect
of the bronchial cartilage,
• the fourth layer (hypoechoic) represents bronchial cartilage, and
• the fifth layer (hyperechoic) is the marginal echo on the outer aspect
of the bronchial cartilage.

9. • For determination of the depth of tracheobronchial tumor invasion
using EBUS, one must carefully examine the third and fourth layers
that correspond to the bronchial cartilage.
• An important limitation of preoperative EBUS in determination of the
depth of tumor invasion is difficulty in distinguishing lymphocytic
infiltration from tumor invasion.
• As ultrasonography visualizes tissues according to the speed of
propagation of ultrasound waves, it is seen that the speed of
ultrasound waves from the 20 MHz probe passing through invasive
cancer is similar to that through lymphocytic infiltrates and
hypertrophied bronchial glands.

10. EBUS for Peripheral Lesions
• On ultrasound imaging of peripheral lung nodules, the lesions are
classified on the basis of
• internal echo pattern (homogeneous or heterogeneous),
• vascular patency, and
• morphology of hyperechoic areas (reflecting the presence of air and
the state of the bronchi).
• Type I lesions have homogeneous pattern, 92 % of which are benign;
• type II lesions have hyperechoic dots and linear arcs pattern, 99% of
which are malignant, and
• type III lesions have a heterogeneous pattern, 99 % of which are
malignant.

11. Endobronchial Ultrasound with a Guide Sheath
for Biopsy of Peripheral Lesions

12. Equipment

14. Convex probe EBUS

15. Introduction
• The radial probe EBUS has remained useful for a variety of purposes:
• to identify the location of mediastinal nodes before performing
transbronchial needle aspiration (TBNA) procedures
• to evaluate the depth of tumor invasion into the tracheobronchial wall ;
and
• to guide bronchoscopic tools to obtain tissue specimen from solitary
pulmonary nodules and peripheral lesions.
• Although radial probe EBUS allows the operator to visualize the structures
outside the bronchial wall, realtime guidance for the biopsy of lesions
beyond the airway wall is not feasible.
• To overcome this limitation, a convex probe EBUS which is built directly
onto the distal tip of the bronchoscope has been developed that allows for
real-time visualization and guided biopsy of mediastinal Structures.

16. Mediastinal Sampling – Need for EBUS TBNA
• Mediastinoscopy –good yield, but highly invasive
• Conventional TBNA – less invasive but yield variable
• All lymph node stations can not be sampled with either
• EBUS-TBNA has emerged as a technique that combined the high yield
of mediastinoscopy with the minimal invasiveness of TBNA.

17. Indications
• The main indications of EBUS-TBNA are the mediastinal and hilar
staging of ca. Lung, diagnosis of suspected cancer when no
endobronchial lesion is present in patients with lymphadenopathy,
and recurrence or restaging of NSCLC after chemotherapy or
radiation.
• Other indications include any causes of mediastinal lymphadenopathy
such as suspected sarcoidosis, infections such as tuberculosis,
mediastinal lymphoma, thymoma, and mediastinal cysts.
• In addition, EBUS-TBNA can assist in guiding therapy by measuring
the depth of tumor invasion into the airway wall, or for tissue banking
and molecular testing.

18. Equipment and Technique
• The EBUS scope is generally larger and stiffer than a standard
bronchoscope .
• The external diameter of the Olympus EBUS scope is 6.2 mm and the tip of
EBUS scope is 6.9 mm, as compared with the typical 5–6 mm uniform
diameter of standard bronchoscopes.
• It has a 2.0 mm instrument channel for introducing a dedicated 22-gauge
or 21-gauge TBNA needle for the procedure.
• The scope allows simultaneous display of two images: an ultrasound image
and an airway image.
• The ultrasound image is at 90 degrees to the EBUS tip shaft, and
encompasses a 50-degree slice of this region.
• The probe has a frequency of 7.5 MHz that can obtain images from a depth
of penetration of up to 9 cm.

20. • The optical view of the EBUS scope is 30 degrees to the horizontal,
not the typical 0-degree view of a standard scope.
• This has practical implications in that to obtain a forward 0-degree
view, the scope must be flexed to −30 degrees; otherwise one can
unknowingly injure the vocal cords or bronchial wall if the
bronchoscope is advanced in neutral position.
• The needle channel is built such that the EBUS-TBNA needle placed
through the scope extends at an angle of 20 degrees to its axis as it
emerges out of the distal tip.
• The channel angulation is needed to ensure real-time ultrasound
visualization of the biopsy needle as it is advanced through the airway
and into the lymph node
• The EBUS TBNA needle is longer, grooved with stylet.

21. Procedure
• Identify the node to be sampled using the ultrasound image
• Proper identification of the nodal station can be carried out through both
direct visualization of where the tip of the scope lies as well as through the
visualization of anatomic structures within the ultrasound image’s field of
view
• the EBUS needle catheter is advanced through the working channel and
locked in position
• Needle is advanced till visualized in usg image
• Once within the node,
• the inner stylet should be tapped or slightly withdrawn and advanced
several times to eject any debris that may have collected during insertion
through the bronchial wall.

24. Complications
• pneumomediastinum,
• pneumothorax,
• hemomediastinum,
• mediastinitis,
• bacteremia
• Similar to conventional TBNA procedure, bleeding complications are
rare, even if major vessels are punctured inadvertently.

25. THANKYOU