What is Magnetic Resonance Imaging (MRI) elastography?

From the Guidelines

Magnetic Resonance Imaging (MRI) elastography is a non-invasive medical imaging technique that measures tissue stiffness by combining traditional MRI technology with mechanical waves, and it is particularly valuable for assessing liver fibrosis and cirrhosis without the need for invasive biopsies. This technique works by sending sound waves through the tissue being examined while the MRI scanner captures images of the resulting tissue movement, and the data is then processed to create color-coded maps showing tissue elasticity, with stiffer areas potentially indicating disease 1. The procedure typically takes 10-15 minutes as an addition to a standard MRI exam and requires patients to hold their breath briefly while images are captured.

Key Points

• MRI elastography is a specialized medical imaging technique that measures the stiffness of tissues in the body by combining traditional MRI technology with mechanical waves.
• It is particularly valuable for assessing liver fibrosis and cirrhosis without the need for invasive biopsies, allowing physicians to detect and monitor liver disease progression.
• The technology works on the principle that diseased tissues often have different mechanical properties than healthy ones; for example, fibrotic liver tissue becomes stiffer than normal liver tissue.
• Beyond liver assessment, MRI elastography is increasingly being used to evaluate other organs including the brain, breast, kidneys, and muscles for various pathological conditions.
• According to a recent study, MRI elastography shows high diagnostic accuracy for liver fibrosis, with a diagnostic performance superior to that of transient elastography 1.
• Another study found that MRI elastography is the most accurate non-invasive test for liver fibrosis, with a diagnostic performance superior to that of transient elastography 1.
• However, it's worth noting that MRI elastography may have limitations in patients with hepatic iron deposition and patients imaged at 3T due to susceptibility artifacts, which can result in undersampling of the liver or nondiagnostic evaluations 1.

From the Research

Definition of MRI Elastography

• MRI elastography, also known as Magnetic Resonance Elastography (MRE), is a noninvasive imaging technique that quantitatively measures the mechanical properties of tissues in vivo 2, 3.
• It uses a vibration source to generate low-frequency mechanical waves in tissue, which are then imaged using a phase-contrast MRI technique 2.
• The wave information is processed to generate quantitative images showing mechanical properties such as tissue stiffness 2.

Principles and Technique

• MRE employs the same physical property that physicians utilize when performing manual palpation, differentiating healthy and diseased tissues based on mechanical stiffness 3.
• The technique involves "virtual palpation" to provide information beyond conventional morphologic imaging modalities 3.
• MRE can be seamlessly incorporated into a standard MRI examination to provide a rapid, reliable, and comprehensive imaging evaluation at a single patient appointment 3.

Clinical Applications

• MRE has been explored for various clinical applications, including brain, thyroid, lung, heart, breast, and skeletal muscle imaging 2.
• The best-documented application of MRE is the assessment of liver disease, particularly liver fibrosis 2, 4, 5.
• MRE has also been used in the field of oncology for tumor diagnosis, selection of treatment method, and prognosis evaluation 6.

Advantages and Limitations

• MRE has several advantages, including the ability to evaluate larger liver volumes, perform assessments in obese patients and those with ascites, and provide a more precise analysis of viscoelastic parameters 4.
• However, MRE is more expensive than other noninvasive methods, such as ultrasound elastography, which may limit its use 4.