Tissue Stiffness: MR Elastography: Case Study/Application
Lauriane Jugé1
1Neuroscience Research Australia, Sydney, Australia

Synopsis

Keywords: Contrast mechanisms: Elastography

This talk will present key clinical applications of MR elastography. MR elastography is a useful imaging technique for mapping the mechanical properties of soft tissues in vivo, such as the brain, liver, muscles, or tumours. It is an established diagnostic technique for staging liver fibrosis and has increasing relevance in investigating complex physiological and pathological processes, including neurodegenerative diseases and cancers. Recent advancements in MR elastography, allowing mapping of anisotropic tissue properties and characterisation of nonlinear viscoelastic behaviour under static loading, will also be covered to discuss future applications of MR elastography.

Purpose

This talk will 1- explore some of the key clinical applications of MR elastography [1], a non-invasive imaging technique used to measure viscoelastic properties of soft tissue, 2- demonstrate how MR elastography can be used to investigate complex physiological and pathological processes, and 3- discuss recent advancements and future applications of MR elastography.

Clinical applications of MR elastography

MR elastography has been used on the basis that changes in microstructures are reflected in altered soft tissue mechanical properties [2]. Some of the key clinical applications of MR elastography include:
  • Liver. The most significant and established clinical application of MR elastography is in diagnosing and staging liver fibrosis (liver stiffness increases with fibrosis severity) and detecting early cirrhosis [3]. When combined with clinical indicators, MR elastography is also useful for diagnosing non-alcoholic steatohepatitis in patients with non-alcoholic fatty liver disease [4]
  • Brain. A promising clinical application of MR elastography is in measuring the mechanical properties of the brain, i.e. where tissue palpation is not possible [5]. Brain MR elastography studies have reported progressive decreases in brain stiffness with healthy ageing. Patients with Alzheimer's disease or frontotemporal dementia have a soften brain than cognitively healthy controls.
  • Muscle. Another key clinical application of MR elastography is in measuring the mechanical properties of muscle. Studies have reported increased medial gastrocnemius stiffness after eccentric exercise [6], and reduced tongue stiffness in patients with obstructive sleep apnoea compared to healthy controls [7]. Reductions in thigh muscle stiffness have also been reported with ageing [8]. There is also potential for cardiac MR elastography [9].
  • Tumours. MR elastography has the potential to provide a new strategy for early tumour diagnosis. Cancerous liver, breast, pancreatic and prostate tissue has been reported to be stiffer than healthy tissue or benign tumours [10].

Recent advancements in MR elastography for research applications

  • Anisotropic MR elastography. Clinical MR elastography assumes all tissues are isotropic. However, as muscle and white brain matter are anisotropic, this can lead to inaccurate estimates of the mechanical properties of these tissues. Combining MR elastography and diffusion tensor imaging to identify the fibre directions and characterise the perpendicular and parallel shear moduli is one approach to enhance the detection of tissue pathologies in anisotropic soft tissues in vivo (e.g. [11]).
  • Nonlinear viscoelastic behaviour under static loading. Knowledge of the nonlinear viscoelastic properties of soft tissues under large strains is relevant to a wide range of clinical and research fields, including tissue engineering, mechanobiology, computer-based simulators and clinical diagnostics. Combining static loading or passive muscle stretching with MR elastography is a useful imaging method for assessing those properties, as shown in ex vivo liver [12], preclinical models [13] , and muscles [14].

Conclusions

MR Elastography is a very useful imaging technique for measuring the stiffness of the liver, brain, muscles, and other soft tissues in vivo. By providing complementary information to other imaging modalities, e.g. diffusor tensor imaging, it has great potential for clinical use in healthy ageing, cancer, neurodegeneration and other disorders. Recent advancements in MR elastography will broaden the scope of MR elastography clinical applications.

Acknowledgements

No acknowledgement found.

References

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Proc. Intl. Soc. Mag. Reson. Med. 31 (2023)