Magnetic resonance elastography

Magnetic resonance elastography (MRE) is a non-invasive medical imaging technique that measures the mechanical properties (stiffness) of soft tissues by introducing shear waves and imaging their propagation using MRI. Diseased tissues are often stiffer than the surrounding normal tissue. For instance, breast cancers are much harder than healthy fibroglandular tissue. This characteristic has been used by physicians for screening and diagnosis of many diseases, through palpation. MRE calculates the mechanical parameter as elicited by palpation, in a non-invasive and objective way.[citation needed]

Magnetic resonance elastography works by using an additional gradient waveform in the pulse sequence to sensitize the MRI scan to shear waves in the tissue. The shear waves are generated by an electro-mechanical transducer on the surface of the skin. Both the mechanical excitation and the motion sensitizing gradient are at the same frequency. This encodes the amplitude of the shear wave in the tissue in the phase of the MRI image. An algorithm can be used to extract a quantitative measure of tissue stiffness from the MRI in an elastogram.[citation needed]

Magnetic resonance elastography was first introduced by Muthupillai et al. in 1995[1] and is being investigated to be used for a multitude of diseases that affect the tissue stiffness.[2][3] It has been used clinically for the assessment of liver fibrosis.[4][5][6]

Liver fibrosis is a common result of many chronic liver diseases and if progressive leads to cirrhosis. Magnetic Resonance Elastography of the liver provides quantitative maps of tissue stiffness over large regions of the liver. This non-invasive technique is able to detect increased stiffness of the liver parenchyma, which is a direct consequence of liver fibrosis. It helps to stage liver fibrosis or diagnose mild fibrosis with reasonable accuracy.[7]

Magnetic Resonance Elastography of the brain was first presented in the early 2000s[8][9] and its measures have been correlated with memory tasks,[10] fitness measures[11] and various neurodegenerative conditions: Alzheimer’s Disease[12][13] and Multiple Sclerosis[14] to name a few. It has been found that as the brain ages, it loses its viscoelastic integrity due to degeneration of neurons and oligodendrocytes.[15][16]

Brain MRE has only just begun for use in adolescents, and it shows potential towards understand adolescent pathology, recently it has found that adolescents have regionally different brain viscoelasticity than adults.[17][18]

  1. ^ Muthupillai R, Lomas DJ, Rossman PJ, Greenleaf JF, Manduca A, Ehman RL (September 1995). “Magnetic resonance elastography by direct visualization of propagating acoustic strain waves”. Science. 269 (5232): 1854–7. Bibcode:1995Sci…269.1854M. doi:10.1126/science.7569924. PMID 7569924.
  2. ^ Mariappan YK, Glaser KJ, Ehman RL (July 2010). “Magnetic resonance elastography: a review”. Clinical Anatomy. 23 (5): 497–511. doi:10.1002/ca.21006. PMC 3066083. PMID 20544947.
  3. ^ Glaser KJ, Manduca A, Ehman RL (October 2012). “Review of MR elastography applications and recent developments”. Journal of Magnetic Resonance Imaging. 36 (4): 757–74. doi:10.1002/jmri.23597. PMC 3462370. PMID 22987755.
  4. ^ Yin M, Talwalkar JA, Glaser KJ, Manduca A, Grimm RC, Rossman PJ, Fidler JL, Ehman RL (October 2007). “Assessment of hepatic fibrosis with magnetic resonance elastography”. Clinical Gastroenterology and Hepatology. 5 (10): 1207–1213.e2. doi:10.1016/j.cgh.2007.06.012. PMC 2276978. PMID 17916548.
  5. ^ Huwart L, Sempoux C, Vicaut E, Salameh N, Annet L, Danse E, Peeters F, ter Beek LC, Rahier J, Sinkus R, Horsmans Y, Van Beers BE (July 2008). “Magnetic resonance elastography for the noninvasive staging of liver fibrosis”. Gastroenterology. 135 (1): 32–40. doi:10.1053/j.gastro.2008.03.076. PMID 18471441.
  6. ^ Asbach P, Klatt D, Schlosser B, Biermer M, Muche M, Rieger A, et al. (October 2010). “Viscoelasticity-based staging of hepatic fibrosis with multifrequency MR elastography”. Radiology. 257 (1): 80–6. doi:10.1148/radiol.10092489. PMID 20679447.
  7. ^ Venkatesh, Sudhakar K.; Yin, Meng; Ehman, Richard L. (March 2013). “Magnetic resonance elastography of liver: Technique, analysis, and clinical applications”. Journal of Magnetic Resonance Imaging. 37 (3): 544–555. doi:10.1002/jmri.23731. PMC 3579218. PMID 23423795.
  8. ^ Van Houten EE, Miga MI, Weaver JB, Kennedy FE, Paulsen KD (May 2001). “Three-dimensional subzone-based reconstruction algorithm for MR elastography”. Magnetic Resonance in Medicine. 45 (5): 827–37. doi:10.1002/mrm.1111. PMID 11323809.
  9. ^ Van Houten EE, Paulsen KD, Miga MI, Kennedy FE, Weaver JB (October 1999). “An overlapping subzone technique for MR-based elastic property reconstruction”. Magnetic Resonance in Medicine. 42 (4): 779–86. doi:10.1002/(SICI)1522-2594(199910)42:4<779::AID-MRM21>3.0.CO;2-Z. PMID 10502768.
  10. ^ Schwarb H, Johnson CL, McGarry MD, Cohen NJ (May 2016). “Medial temporal lobe viscoelasticity and relational memory performance”. NeuroImage. 132: 534–541. doi:10.1016/j.neuroimage.2016.02.059. PMC 4970644. PMID 26931816.
  11. ^ Schwarb H, Johnson CL, Daugherty AM, Hillman CH, Kramer AF, Cohen NJ, et al. (June 2017). “Aerobic fitness, hippocampal viscoelasticity, and relational memory performance”. NeuroImage. 153: 179–188. doi:10.1016/j.neuroimage.2017.03.061. PMC 5637732. PMID 28366763.
  12. ^ Murphy MC, Jones DT, Jack CR, Glaser KJ, Senjem ML, Manduca A, Felmlee JP, Carter RE, Ehman RL, Huston J (2016). “Regional brain stiffness changes across the Alzheimer’s disease spectrum”. NeuroImage. Clinical. 10: 283–90. doi:10.1016/j.nicl.2015.12.007. PMC 4724025. PMID 26900568.
  13. ^ Murphy MC, Huston J, Jack CR, Glaser KJ, Manduca A, Felmlee JP, Ehman RL (September 2011). “Decreased brain stiffness in Alzheimer’s disease determined by magnetic resonance elastography”. Journal of Magnetic Resonance Imaging. 34(3): 494–8. doi:10.1002/jmri.22707. PMC 3217096. PMID 21751286.
  14. ^ Sandroff BM, Johnson CL, Motl RW (January 2017). “Exercise training effects on memory and hippocampal viscoelasticity in multiple sclerosis: a novel application of magnetic resonance elastography”. Neuroradiology. 59 (1): 61–67. doi:10.1007/s00234-016-1767-x. PMID 27889837.
  15. ^ Sack I, Beierbach B, Wuerfel J, Klatt D, Hamhaber U, Papazoglou S, et al. (July 2009). “The impact of aging and gender on brain viscoelasticity”. NeuroImage. 46(3): 652–7. doi:10.1016/j.neuroimage.2009.02.040. PMID 19281851.
  16. ^ Sack I, Streitberger KJ, Krefting D, Paul F, Braun J (2011). “The influence of physiological aging and atrophy on brain viscoelastic properties in humans”. PLOS One. 6 (9): e23451. Bibcode:2011PLoSO…623451S. doi:10.1371/journal.pone.0023451. PMC 3171401. PMID 21931599.
  17. ^ Johnson CL, Telzer EH (October 2018). “Magnetic resonance elastography for examining developmental changes in the mechanical properties of the brain”. Developmental Cognitive Neuroscience. 33: 176–181. doi:10.1016/j.dcn.2017.08.010. PMC 5832528. PMID 29239832.
  18. ^ McIlvain G, Schwarb H, Cohen NJ, Telzer EH, Johnson CL (November 2018). “Mechanical properties of the in vivo adolescent human brain”. Developmental Cognitive Neuroscience. 34: 27–33. doi:10.1016/j.dcn.2018.06.001. PMC 6289278. PMID 29906788.


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