The document discusses ultrasound elastography, a technique used to assess tissue stiffness and liver fibrosis through various methods such as transient elastography and shear wave elastography. It highlights the principles of elasticity and the different forms of elastography used to measure mechanical properties of tissues, especially in the context of chronic liver diseases. Clinical applications include staging liver fibrosis, monitoring treatment response, and the importance of accurate imaging techniques in diagnosing liver conditions.

1. Ultrasound
Elastography
Dr Manoj K S MD RD DNB RD
Consultant Radiologist
KIMS HOSPITAL
PIONEER METRO SCANS

2. Perspective counts
Perspective alters
Perspective matters

5. Physics
Practical
Cases
Pathology

6. LABS
IMAGING
PATHOLOGY
platelet count, prothrombin time,
albumin level, total bilirubin level,
and serum aminotransferase levels,
to more sophisticated tests,
including levels of hyaluronic acid
and a2-macroglobulin. Direct
markers of brosis include levels of
procollagen (types I, III, and IV),
matrix metalloproteinases,
cytokines, and chemokines.
HEPASURE
FIBROSCORE
FIBROMETRE
US ELASTOGRAPHY
MR ELASTOGRAPHY Ishak
METAVIR
Batts- Ludwig
systems
Liver Fibrosis assessment

7. Lab Tests

8. Palpation as age old technique to assess liver/tissue stiffness

9. ELASTOGRAPHY

10. The elasticity of a material describes its
tendency to resume its original size and shape
after being subjected to a deforming force or
stress.
The change in size or shape is known as the
strain.
The force acting on unit area is known as the
stress.
Elastography refers to an imaging technique
that images and/or quantifies elasticity
(mechanical properties) of biologic tissues

11. Ultrasound creates the propagation of a
transient density deformation.
In soft tissues, it travels at speeds in the range
of 1350 – 1600 ms–1, whereas shear
deformation travels much slower, in the range
of 1 – 10 ms–1 .
This speed difference means that ultrasound
may be used to measure tissue displacements
at precise phases of shear deformation.

12. Elastography methods take advantage of the changed
elasticity of soft tissues resulting from specific
pathological or physiological processes .Fibrosis
associated with chronic liver diseases causes the liver
to become stiffer than normal tissues.
3 types of elastic moduli defined
by the method of deformation:
Young’s modulus (E), shear
modulus (G), bulk modulus (K).

13. Young’s modulus (E), shear modulus (G), bulk modulus (K).

15. Elastography produces a force coupled with a measurement
system for the deformities caused by the force
• There are several types of forces or applications:
• Static compression induced externally by manual
compression or internally by organ motion (heart, vessel,
breathing);
• Dynamic compression induced with a continuous
vibration at a given frequency
• Impulse compression(transient vibration):induced
externally by a transient mechanical impulse (FibroScan®
)
or internally by an ultrasound impulse (ARFI, SWE), both
compression types producing shear waves.

17. Strain elastography can be further subdivided :
I The operator exerts manual compression on the tissue
with the ultrasound transducer. Manual compression
works fairly well for superficial organs such as the breast
and thyroid but is challenging for assessing elasticity in
deeper located organs such as the liver.
II In excitation method, the ultrasound transducer is held
steady, and tissue displacement is generated by internal
physiologic motion (e.g. cardiovascular, respiratory).
Since this method is not dependent on superficially
applied compression, it may be used to assess deeper
located organs

19. 1D Transient Elastography
• The Fibroscanprobe is a single device that contains both an
ultrasound transducer and a mechanical vibrating device.
Although 1D-TE is an US-based technique, it is used without
direct B-mode image guidance.
• The operator selects the imaging area using time-motion
ultrasound (based on multiple A-mode lines in time at different
proximal locations assembled to form a low quality image) to
locate a liver portion 2.5 – 6.5 cm below the skin surface and
free of large vascular structures.
• The mechanical vibrating device then exerts a controlled
vibrating external “punch” on the body surface to generate
shear waves which propagate through the tissue.
• The same probe then uses A-mode US to measure the shear
wave speed and Young’s modulus E is calculated .
Measurements assess a tissue volume of approximately 1 cm
wide x 4 cm long, which is >100 times larger than the average
volume of a biopsy sample

22. Transient elastography (TE):
An automated movement of a piston, which is also
a disc-shaped ultrasound transduc- er, applies a
single cycle 50 Hz push to the body surface with
con- trolled applied force.
The transient shear deformation created in this
way, propagates into the tissue.
Its near constant speed for about 4 cm in the liver
(before being rendered non-detectable due to
attenuation) is measured by a straight line
automatically fitted to the displacement M-mode

23. Criteria for validation
(1) at least 10 valid measurements,
(2) ratio of number of valid
measurements to the total number of
measurements is ≥ 60%,
(3) interquartile range (IQR), which
reflects the variability of measurements,
is less than 30% of the median value of
liver stiffness measurements

24. The ARFI technique
On a conventional gray-scale US
image (oblique scan including the
right kidney and the lowest portion
of the right lobe of the liver),
acoustic push pulses (curved
lines) are generated together with
the main US beam. From the push
pulses originate shear waves
(dashed horizontal lines)
propagating perpendicular to the
main US beam, which are
sampled by tracking beams
(arrows) parallel to the main beam.

25. Point shear wave elastography
In this technique, ARFI is used to induce tissue displacement in
the normal direction in a single focal location, similar to ARFI
strain imaging.
Unlike ARFI strain imaging, the tissue displacement itself is not
measured.
Instead, a portion of the longitudinal waves generated by ARFI is
intra-converted to shear waves through the absorption of
acoustic energy .
The speed of the shear waves perpendicular to the plane of
excitation cs are measured, which are either directly reported or
converted Young’s modulus E and reported to provide a
quantitative estimate of tissue elasticity

26. Point shear wave elastography
ARFI is used to induce tissue displacement in the normal
direction in a single focal location, similar to ARFI strain
imaging. Unlike ARFI strain imaging, the tissue
displacement itself is not measured.
Instead, a portion of the longitudinal waves generated by
ARFI is intra-converted to shear waves through the
absorption of acoustic energy .
The speed of the shear waves perpendicular to the plane of
excitation cs are measured, which are either directly reported
or converted Young’s modulus E and reported to provide a
quantitative estimate of tissue elasticity .

27. 2D Shear Wave Elastography®
(SWE)
It is based on the generation of a radiation force in the tissue to
create the shear wave. The ultrasound probe of the device
produces a very localized radiation force deep in the tissue of
interest. This acoustic radiation force/push induces a shear wave,
which then propagates from this focal point.
Several focal points are then generated almost simultaneously, in
a line perpendicular to the sur- face of the patient’s skin.
This creates a conical shear wave front, which sweeps the image
plane, on both sides of the focal point. The progression of the
shear wave is captured by the very rapid acquisition of ultrasound
images (up to 20,000 images per second), called UltraFastTM
Imaging.

28. Shear Wave Elastography®
(SWE)
The acquisition takes only a few milliseconds, thus the patient or
operator movement does not impact the result. A high- speed
acquisition is necessary to capture the shear wave as it moves at
a speed in the order of 1 to 10 m/s.
A comparison of two consecutive ultrasound images allows the
measurement of displacements induced by the shear wave and
creates a ‘‘movie’’ showing the propagation of the shear wave
whose local speed is intrinsically linked to elasticity.
The propagation speed of the shear wave is then estimated from
the movie that is created and a two-dimensional color map is
displayed, for which each color codes either the shear wave
speed in meters per second (m/s), or the elasticity of the medium
in kilopascals (kPa).

29. Shear Wave Elastography®
This color map is accompanied by an anatomic reference gray
scale (or B-mode) image. This quantitative imaging technique
is a real-time imaging mode.
Quantitative measurements can be performed in the color
window by positioning one or more ROI (regions of interest)
The ROI are variable in size (from 3 mm2
to 700 mm2
).
Measurements can be performed retrospectively from the
saved image or cineloop. The measurements provided are the
mean, standard deviation, and minimum and maximum
elastography values. Results are given in m/s or kPa

32. Pathophysiology
correlation

37. METAVIR 2

38. METAVIR 4

39. BRIDGING FIBROSIS

40. NODULE

42. Staging of liver fibrosis in hepatitis C virus infection according to Ishak
(6 stages) Trichrome stain of 4 liver biopsies showing different stages;
fibrous tissue is stained blue and hepatocytes pink. A, No fibrosis,
Ishak stage 0 of 6. B, Periportal fibrosis, Ishak stage 2 of 6. C,
Advanced bridging fibrosis, Ishak stage 4 of 6. D, Complete cirrhosis,
Ishak stage 6 of 6.

43. Diagram of the comparison of the various staging systems for liver fibrosis

46. •Portal Pressure Measurements
• Safest and most reproducible is Hepatic Venous Pressure
Gradient
• HVPG = WHVP-FHVP
• WHVP is the wedged hepatic venous pressure and
reflects sinusoidal pressure
• FVHP is the Free Hepatic Venous Pressure and reflects
the Systemic blood pressure (internal 0)
• Normal HVPG is 3 to 5 mm Hg

47. Why staging important in
management
• Prognostication – assess urgency for treatment
• Surveillance in cirrhotic patients (HCC,varices)
• Baseline for treatment response
• Tailoring of treatment algorithms (eg in HCV)
• Drug reimbursement

48. The main clinical indication for liver elastography
is staging of chronic liver disease and the main
objective of determining the presence or absence
of advanced fibrosis
For the clinician, the most important question in a
patient with chronic liver disease is whether or not
the patient has cirrhosis

50. Regression of liver fibrosis over 5 years of treatment with disoproxil fumarate (TDF),

56. Practical

57. How to Perform SWE
• An intercoastal approach to right lobe of liver is preferred .Patient should
raise the right arm above head to increase the intercoastal spaces
• Optimize the B mode image – Best acoustic window
• Measurements should be taken in breathhold in a neutral brething position
• Measurements should be taken in the right lobe of liver
• Take measurements 2 cm deep to the capsule
• Avoid large vessels and bile ducts
• ARFI pulse should be perpendicular to liver capsule

60. Best Practice for Performance of US-based
Elastography
Fasting for 4–6 hours
Specific positioning
Supine or slight (30°) left lateral decubitus position
Right arm elevated above the head Shallow breath hold
ROI placement in the right lobe of liver (typically segment VII or
VIII) about 2 cm beneath the Glisson capsule, perpendicular to
the liver capsule
ROI placement to avoid large liver vessels and/or bile ducts
and rib shadows
Ten measurements obtained in the same location

67. Cases

79. Normal

81. NAFLD

83. FATTY LIVER

85. Early fibrosis