Elastography

Medical imaging technique to map tissue stiffness

Elastography is a medical imaging modality that maps the elastic properties and stiffness of soft tissue. It is used to detect and characterize various diseases, particularly those that alter the mechanical properties of tissues, such as cancer and fibrosis.

Principles of Elastography

Elastography is based on the principle that pathological changes in tissue often result in changes in its mechanical properties. For instance, cancerous tissues are generally stiffer than normal tissues. Elastography techniques measure the response of tissue to an applied force, which can be mechanical, acoustic, or electromagnetic, and then calculate the tissue's stiffness or elasticity.

Techniques of Elastography

There are several techniques used in elastography, each with its own advantages and applications:

Ultrasound Elastography

Ultrasound elastography uses sound waves to measure tissue stiffness. It includes methods such as:

• Strain Elastography: This technique involves applying a mechanical compression to the tissue and measuring the resulting strain. It is often used in breast and thyroid imaging.

• Shear Wave Elastography: This method generates shear waves within the tissue using focused ultrasound beams. The speed of these waves is measured to determine tissue stiffness. It is commonly used in liver and musculoskeletal imaging.

Elastography of papillary thyroid carcinoma.

Magnetic Resonance Elastography (MRE)

Magnetic resonance elastography uses MRI to visualize the propagation of mechanical waves through tissues. It is particularly useful for imaging the liver and brain.

Transient Elastography

Transient elastography is a non-invasive method that uses a mechanical impulse to generate shear waves in the liver. It is widely used for assessing liver fibrosis.

File:VCTE, normal and cirrhotic livers.tif

Comparison of normal and cirrhotic livers using transient elastography.

Applications of Elastography

Elastography is used in various clinical applications, including:

Breast Imaging

Elastography is used to differentiate between benign and malignant breast lesions. Malignant tumors tend to be stiffer than benign ones.

File:Breast self-exam illustration (series of 6) (3).jpg

Illustration of breast self-exam, a complementary practice to elastography in breast cancer detection.

Liver Fibrosis Assessment

Elastography is a key tool in assessing liver fibrosis, providing a non-invasive alternative to liver biopsy.

Thyroid Nodule Evaluation

Elastography helps in evaluating thyroid nodules, distinguishing between benign and malignant nodules based on stiffness.

File:Bojunga et al. 2012 ARFI papillary thyroid carcinoma.png

ARFI elastography of papillary thyroid carcinoma.

Musculoskeletal Imaging

Elastography is used to assess muscle stiffness and detect abnormalities in musculoskeletal tissues.

File:Killian Bouillard, Nordez A, Hug F (2011) supersonic shear imaging of hand muscle stiffness.tif

Supersonic shear imaging of hand muscle stiffness.

Advantages and Limitations

Elastography offers several advantages, including being non-invasive, providing quantitative data, and enhancing the diagnostic accuracy of conventional imaging techniques. However, it also has limitations, such as operator dependency and variability in results due to different equipment and techniques.

Related Pages

• Ultrasound imaging
• Magnetic resonance imaging
• Liver biopsy
• Breast cancer