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BY-
DR.SAHIL CHAUDHRY
MODERATOR-
DR.BHARATH SHETTY
AJIMS MANGALORE
OUTLINE
• Introduction
• Physics
• Techniques of Elastography and interpretations.
• Clinical Applications
• Conclusion
ELASTOGRAPHY
‘PALPATION IMAGING’
• Ultrasonographic elastography (sonoelastography)-
Noninvasive imaging technique used to...
• Like palpation, elastography
aims to characterise tissue
stiffness.
.The application of US elastography for imaging tiss...
Aim of elastography
• The aim of elastography is to assess tissue stiffness based on 3
steps:
1. Excitation: transmission ...
PHYSICS
• Stress: It is defined as force per unit area. Unit- Pascal.
• Stress can due to:
• Compression-which acts Perpen...
• On applying a time-varying force to a tissue,
two types of mechanical waves are
propagated –
 Compression waves
 Shear...
Compression Wave
Shear Wave
COMPRESSION WAVES SHEAR WAVES
Parallel to the medium displacement Perpendicular to the medium displacement
High velocity (...
PHYSICS
Elasticity
• Tissue stiffness is generally measured by a physical quantity
calledYoung’s modulus and expressed in ...
• Stress = F/A
• Strain = DL/L0
• E = Stress/Strain
•The harder the tissue, the lesser will
be the strain for a given forc...
• Advantages of measuringYoung’s modulus –
 Better characterization of tissues.
 Quantitative reproduction of clinician’...
Typical values of elasticity in different tissues.
• Elasticity (E) and shear wave propagation speed (c) are
linked through the formula:
E = 3ρc²
(ρ = density of tissue in k...
TECHNIQUES OF
ELASTOGRAPHY
• Based on type of force applied –
 Quasi-static Elastography
 Dynamic Elastography
Type of Force Method
Quasi-Static Strain Elastography
Dynamic ARFI (Acoustic Radiation Forced
Impulse) Imaging
Transient E...
Static Elastography
• First elastography technique, developed by the
Ophir Group at the beginning of the 1990s.
• Uses a u...
STRAIN ELASTOGRAPHY
Applied Force Mechanical –
a) Active external displacement of tissue surface.
b) Passive internal phys...
STRAIN ELASTOGRAPHY
 Strain Elastography reconstructs a ‘Strain Map’ by
calculating the deformations caused by a static c...
• eSieTouch
STRAIN ELASTOGRAPHY
Advantages - First elastography technique developed; most widely used
and validated.
- Does not requir...
DYNAMIC ELASTOGRAPHY
1. Transient Elastography
2. Acoustic Radiation Force ImagingTechnique
3. Supersonic ShearWave Elasto...
Acoustic Radiation Force Imaging
• It uses a focused ultrasound pulse.
• It provides an estimate of the stiffness of deep ...
 Radiation force slightly displaces the tissue at the
focal spot according to Hooke’s law.
 Displacement profile estimat...
ARFI Imaging
Applied Force Ultrasound induced focused radiation force
impulse at depth
Property
displayed
Displacement
Mea...
Advantages - Less user-dependent.
- Better resolution than SE.
- Better transfer of shear modulus contrast to image
contra...
Transient Elastography
• Probe (3.5 MHz) contains a vibrator and an ultrasound transducer.
• Not imaging guided system -pr...
TRANSIENT ELASTOGRAPHY
Applied Force Mechanically induced – impulse at tissue surface
Property
displayed
Shear wave speed
...
FIBROSCAN
TRANSIENT ELASTOGRAPHY
Advantages - Easy to use.
- Quantification of tissue elasticity.
- Rapid, painless.
- Good reproduc...
Ultra-fast shear wave elastography
• This is the technique developed by Supersonic Imaging also based
on transient elastog...
SHEARWAVE ELASTOGRAPHY
Applied Force Ultrasound induced - radiation force swept over depth
faster than shear-wave speed to...
Advantages - Displayed in real time, like a conventional ultrasound
image.
- Good reproducibility.
- Quantitative value of...
ELASTOGRAPHYTECHNIQUES
STRAIN ARFI TRANSIENT SWE
Applied Force Mech Ultra Mech Ultra
(Mach Cone)
Property Strain Strain Sh...
CLINICAL APPLICATIONS
APPLICATIONS
• Breast Imaging
• Prostate Imaging
• Thyroid Imaging
• Liver Imaging
• Intravascular Strain Imaging
• Cardia...
BREAST
• TECHNIQUE
 Pressure applied on the probe should be as low as
possible.
 Locate B-mode image in centre before ac...
• APPLICATIONS IN BREAST
 Characterization of Benign/Malignant solid lesions.
 Characterization of micro-calcification c...
Characterization of Benign/Malignant solid lesions.
- Can improve specificity of BIRADS score.
- Reclassify BIRADS 3 & 4a ...
• Most important elastographic characteristics in evaluating breast lesions -
size and stiffness criteria.
• Size criterio...
Normal BreastTissue
• Biomechanical testing has shown normal fibro-glandular
breast tissue to be markedly stiffer than nor...
• Normal breast tissue. (a) B-mode US image of the breast shows that a lobule
of normal fatty tissue (f) is hypoechoic wit...
Features on Strain Elastography
Benign Malignant
Softer Harder
Brighter on strain image Darker on strain image
Color red/g...
Tsukuba Scoring
-Semi- quantitative
- Risk of malignancy
increases from 1 to 5.
STRAIN ELASTOGRAPHY
• Category 1
• lesions demonstrate a uniform
pattern of high strain, marked by an
evenly distributed green color
throughou...
• Category 2
• lesions show a heterogeneous but
mostly green color signature,
indicating a predominantly high
strain patte...
Category3
• lesions show a pattern of high peripheral strain with
central low strain pattern, and they produce a small
cen...
• Category 4
• lesions produce a low strain pattern and a
uniformly blue color signature confined to
the visible margin of...
• Category 5
• lesions show a similar blue signature
that extends beyond the lesion into
the adjacent tissues
• Ex.- invas...
SWE
False Positive False Negative
Old/ Calcified / large fibro adenoma Mucinous Ca
Breast Implants Inflammatory Ca
Medullary /...
Elastography of lymph nodes.
- Normal lymph nodes are reniform in shape and
contain a hyperechoic fatty hilum on B-mode U...
 Monitoring treatment response to
neoadjuvant chemotherapy in Ca Breast
patients.
- Changes in stiffness during treatment...
BULL’S EYE ARTIFACT
FIBROADENOMA
LIVER
• TECHNIQUE
 Patient must be lying in a dorsal decubitus
position, with the right arm in maximal abduction.
• Measurements are taken in the right lobe of the
liver through an inter-costal space.
• The SWE box must be placed at lea...
• APPLICATIONS IN LIVER
 Assessment of fibrosis.
 Prediction of cirrhosis-linked complications.
 Assessment of response...
LIVER STIFFNESS
• Evaluates velocity of propagation of a shock wave
within liver tissue (examines a physical parameter of
...
Liver Fibrosis
METAVIR SCORE HISTOLOGY
F0 No Fibrosis
F1 Portal fibrosis without septa; minimal fibrosis
F2 Portal fibrosi...
Cut-off values vary depending on etiology and among
different studies.
 Cut-off values for FibroScan (kPa)
Study ≥ F2 ≥ F...
 Cut-off values for ARFI (m/s)
Study ≥ F2 ≥ F3 ≥ F4
Takahashi et al 1.35 1.55 1.77
Lupsor et al 1.34 1.61 2
Sporea et al ...
• Various stages of liver fibrosis on
SWE.
 Prediction of cirrhosis-linked complications.
– Correlation between FibroScan values &
development of esophageal varices...
 Characterization of LiverTumors.
- Among benign tumors, hepatic adenoma has
greatest stiffness.
- Hemangioma – less shea...
OTHER APPLICATIONS IN LIVER
• Decreased stiffness post anti-viral treatment and
increased stiffness in relapse.
• Splenic ...
LIMITATIONS OF US
ELASTOGRAPHY OF LIVER
 Obesity
 Acute liver injury
 Extrahepatic cholestasis
 Increase CVP
 Ascites...
Thyroid
• Performed with a superficial linear probe, during the conventional
examination.
• Main indication of elastograph...
• INTERPRETATION
 Strain Elastography –Visual comparison of
differences in color – Rago/Asteria Scoring.
 ShearWave Elas...
PROSTATE
• TECHNIQUE
 No specific preparation required.
 Conducted after complete, high qualityTRUS
examination in the t...
• INTERPRETATION
 Normal prostate – Homogenous appearance
with elasticity values below 30 kPa.
 BPH – Central & transiti...
Prostate adenocarcinoma with Gleason score of 6/10. (a) Sagittal endorectal US image with the
prostate gland outlined show...
Benign Prostatic Hyperplasia
• Endorectal US - heterogeneous hypoechoic area or areas in the transitional
zone.
• Foci of ...
Benign prostatic hyperplasia. (a)Transverse B-mode US image demonstrates a mildly prominent
isoechoic area (arrow) in the ...
• The best stiffness cut-off value to differentiate benign from
malignant lesions was found to be 35 and 37 kPa in two
ind...
Value of Elastrography for Staging Prostrate
Cancer :
Allows excellent visualization of prostatic
capsule as soft rim arte...
• APPLICATIONS
 Characterization of abnormal regions
detected by B-mode imaging or Doppler.
 Detection of lesions not se...
RENAL APPLICATIONS
• Assessment of renal fibrosis
- Native kidneys
- Evaluation of transplants
• Characterization of renal...
TESTICULAR DISEASES
• Ideal tissue to be explored by elastography.
• Normal testis – Homogenous, medium level of
elasticit...
ENDOSCOPIC ELASTOGRAPHY
• No special probe required
• Use in hepatobiliary, pancreatic masses
• Also to d/f malignant from...
PREGNANT CERVIX
• Assess the biomechanical properties of cervix.
• Applied to transvaginal ultrasound probe.
• ‘Elastograp...
MUSCULOSKELETAL
APPLICATIONS
• Achilles tendinopathy –The asymptomatic Achilles
tendons are usually hard (86-93%) or may c...
Achilles tendinopathy
RODENT ULCER
CUTANEOUS MALIGNANCIES
USG Elastography for muscles:
• Normal relaxed muscle appears as an inhomogeneous
mosaic of intermediate or increased stif...
PICTURESARECOPYRIGHT PROTECTED
NEW APPROACHES
POROELASTOGRAPHY
– Evaluates Fluid Movement in the Interstitium
OverTime Using Poisson’s Ratio Images
AXIAL...
CONCLUSION
• Elastography – A new modality of ultrasound imaging.
• Characterizes tissue stiffness.
• Types – Quasi-static...
REFERRENCES
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Ultrasound Elastography

presentation on ultrasound elastography-introduction ,techniques,physics,application, interpretation and future prospects.sourced from multiple articles.

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Ultrasound Elastography

  1. 1. BY- DR.SAHIL CHAUDHRY MODERATOR- DR.BHARATH SHETTY AJIMS MANGALORE
  2. 2. OUTLINE • Introduction • Physics • Techniques of Elastography and interpretations. • Clinical Applications • Conclusion
  3. 3. ELASTOGRAPHY ‘PALPATION IMAGING’ • Ultrasonographic elastography (sonoelastography)- Noninvasive imaging technique used to depict relative tissue stiffness or displacement (strain) in response to imparted force. • Stiff tissues deform less and exhibit less strain than compliant tissues in response to the same applied force.Thus, the basis of elastography is analogous to manual palpation
  4. 4. • Like palpation, elastography aims to characterise tissue stiffness. .The application of US elastography for imaging tissues first described in 1987 by Krouskop et al. Since its inception, sonoelastography is used to evaluate numerous types of tissues, including breast, prostate, liver, blood vessels, thyroid, and musculoskeletal structures.
  5. 5. Aim of elastography • The aim of elastography is to assess tissue stiffness based on 3 steps: 1. Excitation: transmission of stress in a tissue (mechanical, vibrational, shear). 2. Acquisition: recording the signal induced by the tissue deformation due to the stress . 3. Analysis/post-treatment: analysis of tissue strain induced by the propagation of the stress.
  6. 6. PHYSICS • Stress: It is defined as force per unit area. Unit- Pascal. • Stress can due to: • Compression-which acts Perpendicular to the surface and causes shortening of an object Shear stress which acts parallel to the surface and causes deformation.
  7. 7. • On applying a time-varying force to a tissue, two types of mechanical waves are propagated –  Compression waves  Shear waves
  8. 8. Compression Wave Shear Wave
  9. 9. COMPRESSION WAVES SHEAR WAVES Parallel to the medium displacement Perpendicular to the medium displacement High velocity (∼ 1500 m/s) Low velocity (∼ 1-50 m/s) High frequency Low frequency (10 Hz to 2000 Hz) Depend on Bulk Modulus Depend on Shear Modulus Used in Ultrasound imaging Used in Shear Wave Elastography
  10. 10. PHYSICS Elasticity • Tissue stiffness is generally measured by a physical quantity calledYoung’s modulus and expressed in pressure units - Pascals or kilo Pascals (kPa). • TheYoung’s modulus is defined simply as the ratio between the applied stress and the induced strain. • Young’s modulus, or elasticity E, quantifies tissue stiffness. • Hard tissues have a higherYoung’s modulus than soft ones.
  11. 11. • Stress = F/A • Strain = DL/L0 • E = Stress/Strain •The harder the tissue, the lesser will be the strain for a given force.
  12. 12. • Advantages of measuringYoung’s modulus –  Better characterization of tissues.  Quantitative reproduction of clinician’s palpation.
  13. 13. Typical values of elasticity in different tissues.
  14. 14. • Elasticity (E) and shear wave propagation speed (c) are linked through the formula: E = 3ρc² (ρ = density of tissue in kg/m3 ∼ 1000 kg/m3) • Hence, if the shear wave propagation velocity (c) can be measured, the elasticity of the tissue can be determined.
  15. 15. TECHNIQUES OF ELASTOGRAPHY • Based on type of force applied –  Quasi-static Elastography  Dynamic Elastography
  16. 16. Type of Force Method Quasi-Static Strain Elastography Dynamic ARFI (Acoustic Radiation Forced Impulse) Imaging Transient Elastography Shear Wave Elastography
  17. 17. Static Elastography • First elastography technique, developed by the Ophir Group at the beginning of the 1990s. • Uses a uniform compression at the surface of the body to cause deformation of the tissue. • Compression is applied by the user and the ultrasound scanner calculates and displays the induced deformation.
  18. 18. STRAIN ELASTOGRAPHY Applied Force Mechanical – a) Active external displacement of tissue surface. b) Passive internal physiologically induced. Property displayed Strain (‘ELASTOGRAM’) Measurement Qualitative Imaging Full area image; colour image superimposed on a standard B-mode image Commercial Siemens (eSieTouch) Hitachi (Real-timeTissue Elastography”.)
  19. 19. STRAIN ELASTOGRAPHY  Strain Elastography reconstructs a ‘Strain Map’ by calculating the deformations caused by a static compression imposed by the operator via the ultrasound array.
  20. 20. • eSieTouch
  21. 21. STRAIN ELASTOGRAPHY Advantages - First elastography technique developed; most widely used and validated. - Does not require a complex software. Limitations -Operator dependent. - Absence of a specific quantification. - Limited to superficial organs; i.e. breast, thyroid.
  22. 22. DYNAMIC ELASTOGRAPHY 1. Transient Elastography 2. Acoustic Radiation Force ImagingTechnique 3. Supersonic ShearWave Elastography
  23. 23. Acoustic Radiation Force Imaging • It uses a focused ultrasound pulse. • It provides an estimate of the stiffness of deep tissues, non-accessible by external compression. • After identification of the area of interest by USG imaging, a focused ultrasonic wave is applied. • This wave leads to tissue displacement & a shear wave. • The velocity of the shear wave is measured and expressed in m/s.
  24. 24.  Radiation force slightly displaces the tissue at the focal spot according to Hooke’s law.  Displacement profile estimated by tracking of the ultrasound signal (called speckle) Temporal properties of the displacement profile give information about the stiffness of the medium.
  25. 25. ARFI Imaging Applied Force Ultrasound induced focused radiation force impulse at depth Property displayed Displacement Measurement Qualitative Imaging Single image in a box Commercial Siemens
  26. 26. Advantages - Less user-dependent. - Better resolution than SE. - Better transfer of shear modulus contrast to image contrast. Limitations - Absence of a specific quantification. -Transducer heating limits the frame rate. - Displacement profile depends on the elasticity of the medium, but also on many other parameters, such as geometries of the beam & of the medium. ARFI IMAGING
  27. 27. Transient Elastography • Probe (3.5 MHz) contains a vibrator and an ultrasound transducer. • Not imaging guided system -probe is positioned randomly on skin • Measures are done at a depth between 25 and 65 mm. • Exam takes 5-10 minutes- consists of 10 measures at same location. • Principle- mechanical pulse induced at skin surface by an external vibrator generates a transient shear wave (pulse) that propagates longitudinally. • Velocity & amplitude of shear wave are measured in ROI. • velocityV is converted into kPa, and reflects the tissue stiffness. • It can also compute wave attenuation in decibels per meter dB / m.
  28. 28. TRANSIENT ELASTOGRAPHY Applied Force Mechanically induced – impulse at tissue surface Property displayed Shear wave speed Measurement Quantitative Imaging Single measurement; beam-line average Commercial Echosens (FibroScan)
  29. 29. FIBROSCAN
  30. 30. TRANSIENT ELASTOGRAPHY Advantages - Easy to use. - Quantification of tissue elasticity. - Rapid, painless. - Good reproducibility. Limitations - Difficult in obese patients & in ascites. - Lacks 2D image guidance of the measurement. - Left side of the liver cannot be examined.
  31. 31. Ultra-fast shear wave elastography • This is the technique developed by Supersonic Imaging also based on transient elastography ultrasound pulse. • However they allow the generation of multiple shear wave along a same longitudinal axis (through a compression wave) leading to the propagation of a plane shear wave. • This technique also allows the measurement of the velocity of this plane in each point of the image in real time • Thus providing a 2D quantitative measure of elasticity E in real time, usually expressed by a parametric map in kPa
  32. 32. SHEARWAVE ELASTOGRAPHY Applied Force Ultrasound induced - radiation force swept over depth faster than shear-wave speed to create a Mach cone Property displayed Shear wave speed Measurement Quantitative Imaging Image within a color box; refreshed at up to several per second (5000 images per second). Commercial SuperSonic Imagine
  33. 33. Advantages - Displayed in real time, like a conventional ultrasound image. - Good reproducibility. - Quantitative value of stiffness. -Very short acquisition time (∼30 ms). Limitations - Expensive. - Requires a complex software. SHEARWAVE ELASTOGRAPHY
  34. 34. ELASTOGRAPHYTECHNIQUES STRAIN ARFI TRANSIENT SWE Applied Force Mech Ultra Mech Ultra (Mach Cone) Property Strain Strain Shear wave speed Shear wave speed Measurement Quali Quali Quanti Quanti Commercial Siemens (eSieTouch) Siemens (VTI) Echosens (Fibroscan) SuperSonic (Aixplorer)
  35. 35. CLINICAL APPLICATIONS
  36. 36. APPLICATIONS • Breast Imaging • Prostate Imaging • Thyroid Imaging • Liver Imaging • Intravascular Strain Imaging • Cardiac Elastography • DeepVeinThrombosis • KidneyTransplant Monitoring
  37. 37. BREAST • TECHNIQUE  Pressure applied on the probe should be as low as possible.  Locate B-mode image in centre before activating the elastography mode.  Surround the lesion with adjacent normal tissue.  Avoid non-perpendicular angulated scanning.
  38. 38. • APPLICATIONS IN BREAST  Characterization of Benign/Malignant solid lesions.  Characterization of micro-calcification clusters.  Elastography of lymph nodes.  Monitoring treatment response to neo- adjuvant chemotherapy in Ca Breast patients.
  39. 39. Characterization of Benign/Malignant solid lesions. - Can improve specificity of BIRADS score. - Reclassify BIRADS 3 & 4a lesions. - Useful for malignant lesions presenting as benign on B-mode.
  40. 40. • Most important elastographic characteristics in evaluating breast lesions - size and stiffness criteria. • Size criterion: Difference in the measurement of the longest diameter on the corresponding B-mode image and the elastogram. • Structures that are less compressible than surrounding tissues measure larger on the elastogram than they do on the corresponding B-mode image.Therefore, cancers will be larger on the elastogram than on the conventional US image. • This phenomenon is attributed to the incited by many malignant breast neoplasms.
  41. 41. Normal BreastTissue • Biomechanical testing has shown normal fibro-glandular breast tissue to be markedly stiffer than normal fatty breast tissue by as much as two orders of magnitude. Therefore, at elastography, fatty tissue will appear bright with respect to the adjacent glandular tissue, and normal fibrous parenchyma appears darker.
  42. 42. • Normal breast tissue. (a) B-mode US image of the breast shows that a lobule of normal fatty tissue (f) is hypoechoic with respect to the surrounding glandular tissue (g). (b) US elastogram shows that the fatty tissue (f) surrounded by dense breast tissue appears bright because it is appreciably “softer” than the surrounding glandular tissue.
  43. 43. Features on Strain Elastography Benign Malignant Softer Harder Brighter on strain image Darker on strain image Color red/green (soft) (vendor specific) Color blue (hard) (vendor specific) Tumor diameter<B-mode diameter Tumor diameter>B-mode diameter
  44. 44. Tsukuba Scoring -Semi- quantitative - Risk of malignancy increases from 1 to 5. STRAIN ELASTOGRAPHY
  45. 45. • Category 1 • lesions demonstrate a uniform pattern of high strain, marked by an evenly distributed green color throughout the lesion. • Ex.- LIPOMA
  46. 46. • Category 2 • lesions show a heterogeneous but mostly green color signature, indicating a predominantly high strain pattern of the lesion. • Ex. FIBROADENOMAS
  47. 47. Category3 • lesions show a pattern of high peripheral strain with central low strain pattern, and they produce a small central blue area that is surrounded by a green peripheral color. Ex. -FIBROADENOMA
  48. 48. • Category 4 • lesions produce a low strain pattern and a uniformly blue color signature confined to the visible margin of the lesion • Ex.- Lobular carcinoma
  49. 49. • Category 5 • lesions show a similar blue signature that extends beyond the lesion into the adjacent tissues • Ex.- invasive ductal carcinoma
  50. 50. SWE
  51. 51. False Positive False Negative Old/ Calcified / large fibro adenoma Mucinous Ca Breast Implants Inflammatory Ca Medullary / Papillary Ca Cystic Ca Deep lesions (>4-5 cm)
  52. 52. Elastography of lymph nodes. - Normal lymph nodes are reniform in shape and contain a hyperechoic fatty hilum on B-mode US images.At elastography, these features translate into relative softness of the lymph node, with a slightly lower elastogram-to-B-mode size ratio . - Lymph node that contain metastases tend to appear stiffer and disproportionately larger at elastography
  53. 53.  Monitoring treatment response to neoadjuvant chemotherapy in Ca Breast patients. - Changes in stiffness during treatment could be a potential marker for response. - Elasticity heterogeneity is lost in responders.
  54. 54. BULL’S EYE ARTIFACT
  55. 55. FIBROADENOMA
  56. 56. LIVER • TECHNIQUE  Patient must be lying in a dorsal decubitus position, with the right arm in maximal abduction.
  57. 57. • Measurements are taken in the right lobe of the liver through an inter-costal space. • The SWE box must be placed at least 2 cm away from Glisson’s capsule, away from the vessels. • Breath hold for at least 4 seconds to allow filling of SWE box but, no deep inspiration before breath hold. (No breath hold for FibroScan)
  58. 58. • APPLICATIONS IN LIVER  Assessment of fibrosis.  Prediction of cirrhosis-linked complications.  Assessment of response to Anti-viral treatment.  Characterization of LiverTumors.
  59. 59. LIVER STIFFNESS • Evaluates velocity of propagation of a shock wave within liver tissue (examines a physical parameter of liver tissue which is related to its elasticity) • Rationale : Normal liver is viscous Not favorable to wave propagation Fibrosis increases hardness of tissue Favors more rapid propagation
  60. 60. Liver Fibrosis METAVIR SCORE HISTOLOGY F0 No Fibrosis F1 Portal fibrosis without septa; minimal fibrosis F2 Portal fibrosis with a few septa; moderate fibrosis F3 Septal fibrosis with many septae but no cirrhosis; severe fibrosis F4 Cirrhosis
  61. 61. Cut-off values vary depending on etiology and among different studies.  Cut-off values for FibroScan (kPa) Study ≥ F2 ≥ F3 ≥ F4 Ziol et al 8.8 9.6 14.6 Kim et al 6.2 - 11 Nitta et al 7.1 9.6 11.6
  62. 62.  Cut-off values for ARFI (m/s) Study ≥ F2 ≥ F3 ≥ F4 Takahashi et al 1.35 1.55 1.77 Lupsor et al 1.34 1.61 2 Sporea et al 1.34 1.55 1.8
  63. 63. • Various stages of liver fibrosis on SWE.
  64. 64.  Prediction of cirrhosis-linked complications. – Correlation between FibroScan values & development of esophageal varices. – Higher elasticity values predict a higher risk for HCC. Assessment of response to Anti-viral treatment. - Liver elasticity values fall in parallel with response.
  65. 65.  Characterization of LiverTumors. - Among benign tumors, hepatic adenoma has greatest stiffness. - Hemangioma – less shear stiffness than fibrotic liver. - Cholangiocarcinoma - most stiff. - HCC less stiffer than cholangiocarcinoma.
  66. 66. OTHER APPLICATIONS IN LIVER • Decreased stiffness post anti-viral treatment and increased stiffness in relapse. • Splenic stiffness > 9kPa correlates with portal hypertension. • To d/d between HCV and non HCV infections in liver transplant recipients. • Biopsy site from the stiffest region. • Much larger liver volume assessed then biopsy
  67. 67. LIMITATIONS OF US ELASTOGRAPHY OF LIVER  Obesity  Acute liver injury  Extrahepatic cholestasis  Increase CVP  Ascites  Narrow intercostal spaces
  68. 68. Thyroid • Performed with a superficial linear probe, during the conventional examination. • Main indication of elastography in thyroid disease is the nodule characterization, in addition to B-mode which it does not replace. • Thyroid cancers behave differently according to histology: • Papillary cancer is hard; • Follicular cancers do not increase stiffness. • The presence of calcification can cause false positives. • Metastatic LNs have a higher stiffness.
  69. 69. • INTERPRETATION  Strain Elastography –Visual comparison of differences in color – Rago/Asteria Scoring.  ShearWave Elastography – - Cut-off values beyond which cancer should be suspected. STIFFNESS 50 kPa
  70. 70. PROSTATE • TECHNIQUE  No specific preparation required.  Conducted after complete, high qualityTRUS examination in the transverse & sagittal planes.  Quasi-static elastography requires slight compressions & decompressions, which are induced by transrectal probe.
  71. 71. • INTERPRETATION  Normal prostate – Homogenous appearance with elasticity values below 30 kPa.  BPH – Central & transition zones become heterogeneous & hard, with increased values of elasticity.  Carcinoma – Peripheral zone cancer nodules with elasticity values >35 kPa.
  72. 72. Prostate adenocarcinoma with Gleason score of 6/10. (a) Sagittal endorectal US image with the prostate gland outlined shows no discrete lesion (arrow). (b) Sagittal US elastogram shows strong vibration in the normal prostate tissue and also an area of no vibration (arrow) anteriorly from the midportion of the gland to the base.(c) Photomicrograph (hematoxylineosin stain) of a transverse histologic section that included the corresponding lesion (arrow) at the base shows good correlation, with the deficit noted anteriorly on the elastogram through the selected plane of section (dashed line in a and b) in the midportion of the gland.The smaller lesion outlined in blue in c is outside the plane of the elastogram.
  73. 73. Benign Prostatic Hyperplasia • Endorectal US - heterogeneous hypoechoic area or areas in the transitional zone. • Foci of benign prostatic hyperplasia have elastic moduli (stiffness) that are an order of magnitude greater than those of normal prostate tissues but are less than those of prostate carcinomas. • On elastograms, benign prostatic hyperplasia will appear darker than normal prostate tissue. • However, the difference between benign prostatic hyperplasia and prostate carcinoma can be difficult to discern because benign prostatic hyperplasia also appears darker than the background tissues.
  74. 74. Benign prostatic hyperplasia. (a)Transverse B-mode US image demonstrates a mildly prominent isoechoic area (arrow) in the central zone of the prostate gland. (b) Corresponding transverse elastogram shows that the area of benign prostatic hyperplasia (arrow) is more conspicuous.The lesion demonstrates greater stiffness than the surrounding normal prostate tissue. (c) Photomicrograph (hematoxylineosin stain) shows that there is good correlation between the extent of the lesion (arrow) on the histologic section and the lesion extent on the elastogram.
  75. 75. • The best stiffness cut-off value to differentiate benign from malignant lesions was found to be 35 and 37 kPa in two independent studies. • The shear wave elasticity ratio between the nodule and the adjacent peripheral gland tissue for benign and malignant lesions were 1.5 ± 0.9 and 4.0 ± 1.9 (p < 0,002), respectively
  76. 76. Value of Elastrography for Staging Prostrate Cancer : Allows excellent visualization of prostatic capsule as soft rim artefact.
  77. 77. • APPLICATIONS  Characterization of abnormal regions detected by B-mode imaging or Doppler.  Detection of lesions not seen with any other imaging. Targeting of biopsies.
  78. 78. RENAL APPLICATIONS • Assessment of renal fibrosis - Native kidneys - Evaluation of transplants • Characterization of renal tumors.
  79. 79. TESTICULAR DISEASES • Ideal tissue to be explored by elastography. • Normal testis – Homogenous, medium level of elasticity. • Improves discovery of testicular nodules. • Ability to distinguish between testicular lesions & inflammatory changes based on elasticity.
  80. 80. ENDOSCOPIC ELASTOGRAPHY • No special probe required • Use in hepatobiliary, pancreatic masses • Also to d/f malignant from benign lymph nodes. • Limitations : - inability to control compression. - adjacent aorta, spine, vessels. - difficult to d/f pancreatic tumour from chronic pancreatitis.
  81. 81. PREGNANT CERVIX • Assess the biomechanical properties of cervix. • Applied to transvaginal ultrasound probe. • ‘Elastography Index’ – Larger strain in internal os correlates with successful induction. • No correlation with Bishop score nor cervical length. • Might help identifying women who will have successful induction of labor.
  82. 82. MUSCULOSKELETAL APPLICATIONS • Achilles tendinopathy –The asymptomatic Achilles tendons are usually hard (86-93%) or may contain small areas of mild softening. Distinct softening is found in 50% of tendons with Achilles tendinopathy. • Grade 1 ,blue (hardest tissue) to green (hard tissue); • Grade 2, yellow (soft tissue); • Grade 3, red (softest tissue).
  83. 83. Achilles tendinopathy
  84. 84. RODENT ULCER CUTANEOUS MALIGNANCIES
  85. 85. USG Elastography for muscles: • Normal relaxed muscle appears as an inhomogeneous mosaic of intermediate or increased stiffness with scattered softer areas especially at the periphery or near boundaries. • In inflammatory myopathies USE can show changes in muscle elasticity in correlation with elevated serum markers(increased stiffness due to fibrosis or as reduced stiffness, secondary to fatty infiltration)
  86. 86. PICTURESARECOPYRIGHT PROTECTED
  87. 87. NEW APPROACHES POROELASTOGRAPHY – Evaluates Fluid Movement in the Interstitium OverTime Using Poisson’s Ratio Images AXIAL SHEAR STRAIN ELASTOGRAPHY –Visually Displays the Shear Strain at a Lesion Boundary – Estimates the Degree toWhich a Mass is Bonded to the SurroundingTissue
  88. 88. CONCLUSION • Elastography – A new modality of ultrasound imaging. • Characterizes tissue stiffness. • Types – Quasi-static & Dynamic. • Complementary to B-mode imaging. • Well established diagnostic role in breast & liver pathologies. • Vast scope in future.
  89. 89. REFERRENCES

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