1. Michelle Alexander RDMS
Liver Elastography
Michelle Alexander RDMS

2. Elastography Primer
Types of Elastography
Liver Disease Staging and Causes
Limitations of Liver Biopsies
Liver Elastography Method and Protocol
Reimbursement
Other Elastography Use Cases

3. Elastography Primer
Background, Types and Methods

4. Elastography Background
Manual palpation has been used as a diagnostic tool since Egyptian times. How hard or soft tissue is and how mobile it is, gives physicians indication as to how suspicious (or not) a pathology might be.
Elastography is a form of “palpation” using sound waves to “push” the internal tissue and measure its displacement.
If the tissue cannot be “pushed and displaced”, it is likely hard.
If the tissue can be “pushed and displaced”, it is likely soft.

5. Types of Elastography

6. Strain Elastography
Strain elastography, also known as compression or static elastography, evaluates lesion shape changes that occur when the lesion is compressed. Lesions that are soft deform more than those that are hard.
The elastography scale is based on the amount of tissue deformation. This is a qualitative measure with the display scale variable depending on the tissue stiffness within the imaging FOV.
Most commonly used in breast imaging, BIRADS assessment
Commonly available on most all ultrasound systems

7. Strain elastography technique
The user must either apply light compression and decompression to the organ being imaged, or physiological conditions such as respiration or cardiac pulsations supply the tissue deformation.
This type of elastography allows for qualitative or relative tissue stiffness evaluation.
Measurements are generally a ratio between the ROI and a normal tissue area, a 2D distance ratio between the B-mode ROI and the elastogram ROI, or a combination of both.
Depending on manufacturer, red can be “soft” or “hard”, but is usually adjustable.

8. Strain Elastography

9. Transient Elastography (Fibroscan)
This type of elastography uses a mechanical transducer, placed intercostally to generate tissue deformation and assessment of the shear waves produced.
Only used in the liver for fibrosis/steatosis assessment
Does not have imaging of its own. Without imaging, it is sometimes possible to measure kidney or other anatomy creating false results.
Measurements are in kPa for most precise fibrosis staging.

10. Fibroscan

11. Limitations of Fibroscan
No imaging for sample guidance
Does not work if ascites is present
Costly mechanical transducers
Only used in liver
Not real time
Not global tissue assessment

12. Shear Wave Elastography
Shear Wave elastography, also known as dynamic elastography, uses an ultrasound push pulse to generate shear waves perpendicular to the push pulse. The velocity (Vs) of the shear wave through the tissue is proportional to the stiffness of the lesion. From this, the strain modulus (kPa) can be calculated. Shear Wave elastography is a quantitative measure of stiffness. This is measured in m/s or kPa, depending on manufacturer.
No manual compression is necessary with this technique.
Some systems allow only a fixed size box, generally called “point elastography” for the acquisition, while others have a changeable box size.

13. Shear Wave

14. Liver Disease
Clinical staging with ultrasound and elastography

15. Progression of Chronic Liver Disease

16. Most Common Causes of Chronic Liver Disease
Hepatitis C 26 %
ALD 21 %
NAFLD 18 %
Hep C and ALD 15 %
Hep B 15 %
other 5 %

17. Global Liver Disease
1. Hepatitis C a) 200 million individuals infected worldwide b) 2/3 of all infected have not been identified c) Most common cause of cirrhosis/liver transplantation (US) 2. Hepatitis B a) >350 million individuals infected worldwide b) 1/3 in China

18. Global Liver Disease cont.
3. Non-Alcoholic Fatty Liver Disease a) NAFLD in % of industrialized populations b) NASH in 2-6 % of population US c) % of type II diabetes d) 94 % obese, 67 % overweight, 25 % normal weight 4. Alcoholic Liver Disease a) 2 million in US - 6 to 7 % of population b) 50 % of liver related deaths in US/Germany c) Alcohol consumption in China is growing 400 %

19. Clinical Limitations of Biopsy
1. At least 1 stage difference between right and left lobes in 33% of cases
2. Underestimation of cirrhosis in 10-25% of cases
3. Contraindications:
- Coagulation time
Hemangiomas or vascular tumors
4. Limited sampling of overall liver state

20. Procedural Limitations of Biopsy
1. Hospitalization 2. Cost Euros / $1200 average cost in US 3. Serious complications 0.6% (age, cirrhosis, ... ) 4. Mortality 1-3/10, Patient acceptance 6. Inter- and Intra- observer variability 7. Invasive and painful

21. Clinical Staging
The most common staging scale is called the Metavir scale. Treatment typically begins at F2.

22. Staging Values in kPa and m/s

23. Limiting Factors for Using Shear Wave
Common limitations of B-mode imaging are also limiting factors of an elasto acquisition: a) Respiratory/cardiac motion, most left lobes are currently difficult/not feasible b) Reverb under liver capsule c) Good intercostal window, an average window doesn’t guarantee a good acquistion d) Penetration e) Long, extended breath holds increase portal pressure and subsequently alter liver measurements f) Patient illness or health conditions may affect liver elasticity

24. Image Examples

25. Suggested Liver Elastography Protocol

26. Liver Elastography Preparation and Technique
Many studies have demonstrated the influence of clinical factors on liver stiffness. The evaluation of liver fibrosis using Shear Wave Elastography falls within the framework of a complete examination : the effects of respiration, the cholestasis (bile in the hepatic ducts), hepatic necroinflammatory activity (steatosis for example), a peliosis hepatitis, thrombosis of a hepatic vein (clot),… were found in the literature to influence the liver stiffness. The presence of ascites is not a limitation of liver fibrosis evaluation using Shear Wave.

27. Liver Elastography Suggested Protocol
Patient should be fasting for 6-8 hours
Patient should be lying in a dorsal decubitus position, with the right arm in maximum abduction to make accessible the right hypochondrium for best intercostal access
Select Liver preset and supported transducer
Identify an intercostal access that provides satisfactory B-mode imaging of the right liver parenchyma, and vessel-free if possible.
Optimize the B-mode image as the shear wave signal robustness will depend on B-mode image quality (the limitations known in conventional ultrasound exams also apply for shear wave imaging : narrow intercostal spaces, thick layer of fat,..)
Pressure with the probe can be applied to improve the shear wave generation, as long as physical pressure will be absorbed by ribs without impacting soft tissue.

28. Liver Elastography Protocol Cont.
The most robust acquisition will be performed from 2 cm to 7 cm of depth. Please try to avoid placing the box close to the capsule (near field reverberation).
It is not necessary to ask the patient to take a deep breath as it will influence the liver stiffness. It is ideal to perform the exam with normal breathing, and to just have the patient stop breathing within a normal breathing cycle. Then obtain the elastography acquisition.
 The acquisition should be done in vessel-free liver parenchyma. (pulsatility of vessels can generate some shear waves that will influence the measurement).
Repeat 5-10 times to ensure consistency (means are generally used)

29. Reimbursement

30. CPT Codes and Getting Paid-New in 2019!
There are 3 new CPT codes for elastography:
76981: This is for diffuse assessment such as with liver evaluation
76982: This is for nodule/lesion assessment, such as with breast, thyroid or prostate. This is inclusive of strain, point shear wave and real time shear wave imaging.
76983: This is an add on code for when there are multiple nodules being evaluated. This code can piggyback on
The average reimbursement is ~ $134.80, allowed twice per year for liver elastography.
All of the elastography codes should be added on to the US of whatever organ(s) are being evaluated (such as or )
The RVU’s are .59 for and The RVU’s for are .50.

31. Other Uses for Elastography

32. Some Examples Where Elastography Could Be Useful
Breast: Cyst vs soft solid vs hard solid, therapy monitoring, lesion extension
Prostate: Lesion detection for targeted biopsy, tumor extension
Thyroid: suspicious nodule vs multi-nodular goiter, targeted biopsy
Liver: Fibrosis staging, steatosis
Cervix: Pre-term labor risk assessment
MSK: risk of injury, treatment monitoring, post CVA monitoring, trigger point assessment and needling
IO: Ablation monitoring, embedded tumor visualization
THE FUTURE???

33. Thank you for listening! What questions do you have?