Talk:Diffusion MRI

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History

The main clinical application of diffusion-weighted images has been in the study and treatment of neurological disorders, especially for the management of patients with acute stroke. However, diffusion MRI was originally developed to image the liver. In 1984, fr:Denis Le Bihan, then a medical resident and doctoral student in physics, was asked whether MRI could possibly differentiate liver tumors from angiomas. At that time there were no clinically available MRI contrast media. Le Bihan hypothesized that a molecular diffusion measurement would result in low values for solid tumors, because of some kind of molecular movement 'restriction', while the same measure would be somewhat enhanced in flowing blood. Based on the pioneering work of Stejskal and Tanner in the 1960s he suspected that diffusion encoding could be accomplished using specific magnetic gradient pulses. However this required mixing of such pulses with those used in the MRI sequence for spatial encoding. Thus the diffusion coefficients had to be localized, or mapped on to the tissues. This had never been done before, especially in vivo, with any technique. In the first diffusion MRI paper [1] he introduced the 'b factor' (from his name, "B"ihan) to take into account the existence of cross-terms between applied diffusion-sensitizing and imaging gradient pulses, and the 'apparent diffusion coefficient' (acronym ADC) concept, as "diffusion" measured by MRI in tissues is modulated by several mechanisms (restriction, hindrance, etc.) and other IntraVoxel Incoherent Motions (IVIM), such as blood microcirculation, etc., all the ingredients necessary to make diffusion MRI successfully working. The first images were obtained on an almost 'home-made' 0.5T scanner called 'Magniscan' by then CGR (Companie Générale de Radiologie), a French company located in Buc near Versailles in France (now GEMS European Headquarters) which patented diffusion and IVIM MRI.[2][3]

Indeed, the first trials in the liver were very disappointing, and he quickly switched to the brain. He scanned his own brain and that of some of his colleagues before investigating patients (Fig.1). The world first diffusion images of the normal brain were made public in 1985 in London at the international SMRM meeting and the first diffusion images of the brain of patients were shown at the RSNA meeting in Chicago the same year (then published in Radiology).[4][5][6]

At that time diffusion MRI was a very slow method, very sensitive to motion artifacts. It was not until the availability of echo-planar imaging (EPI) on clinical MRI scanners that diffusion and IVIM MRI (and soon later DTI) could really take off in the early 1990s,[7] as results became much more reliable and free of motion artifacts. This move into the clinical field was the result of an intense and fruitful collaboration between Denis Le Bihan and Robert Turner, who was also at NIH. With Turner's unique expertise in gradient hardware and EPI gained during the years he spent with Peter Mansfield, they were able to obtain the first IVIM-EPI images also with the help of colleagues from General Electric Medical Systems (Joe Maier, Bob Vavrek, and James MacFall). With EPI IVIM and diffusion, images could be obtained in a matter of seconds and motion artifacts became history (of course, new types of artifacts came along later). Interestingly, thanks to EPI, diffusion and IVIM MRI could be extended outside the brain, and the very first hypothesis set by Denis Le Bihan to distinguish tumors from angiomas in the liver was confirmed.[8] Between 1991 and 1992, Aaron Filler, Franklyn Howe and colleagues published the first DTI and tractographic brain images.[9][10]

References

  1. ^ Cite error: The named reference LeBihan1985 was invoked but never defined (see the help page).
  2. ^ Le Bihan, D; Breton E. (1987). "Method to Measure the Molecular Diffusion and/or Perfusion Parameters of Live Tissue". US Patent # 4,809,701. 
  3. ^ Le Bihan, D (1989). "Method for the imaging of intra-voxel movements by NMR in a body". US Patent # 5,092,335. 
  4. ^ Cite error: The named reference LeBihan1986 was invoked but never defined (see the help page).
  5. ^ Le Bihan, D; Breton E.; et al. (1985). "MR Imaging of intravoxel incoherent motions : application to diffusion and perfusion in neurologic disorders". Annual Meeting of the RSNA, Chicago. 
  6. ^ Le Bihan, D; Breton, E; Syrota, A (1985). "In-vivo magnetic resonance of self-diffusion". In James TL. Proceedings of the International Society for Magnetic Resonance in Medicine. Fourth Annual Meeting of the Society for Magnetic Resonance in Medicine. S2. The Barbican, London, United Kingdom: Society for Magnetic Resonance in Medicine. pp. 1238–1239. 
  7. ^ Turner R, Le Bihan D, Maier J, Vavrek R, Hedges LK, Pekar J (1990). "Echo-planar imaging of intravoxel incoherent motion". Radiology. 177 (2): 407–14. PMID 2217777. doi:10.1148/radiology.177.2.2217777. 
  8. ^ Yamada, I; Aung, W; Himeno, Y; Nakagawa, T; Shibuya, H (March 1999). "Diffusion coefficients in abdominal organs and hepatic lesions: evaluation with intravoxel incoherent motion echo-planar MR imaging". Radiology. 210 (3): 617–23. PMID 10207458. doi:10.1148/radiology.210.3.r99fe17617. 
  9. ^ Howe, F. A.; Filler, A. G.; Bell, B. A.; Griffiths, J. R. (December 1992). "Magnetic resonance neurography". Magnetic Resonance in Medicine. 28 (2): 328–338. ISSN 0740-3194. PMID 1461131. 
  10. ^ Filler, A. G.; Howe, F. A.; Hayes, C. E.; Kliot, M.; Winn, H. R.; Bell, B. A.; Griffiths, J. R.; Tsuruda, J. S. (1993-03-13). "Magnetic resonance neurography". Lancet. 341 (8846): 659–661. ISSN 0140-6736. PMID 8095572. 

-- Jytdog (talk) 21:22, 14 October 2017 (UTC)

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