The dependence of nuclear magnetic resonance (NMR) image contrast on intrinsic and pulse sequence timing parameters.


Journal Article

In Nuclear Magnetic Resonance (NMR) the image pixel value is governed by at least three major intrinsic parameters: the spin density N (H), the spin-lattice relaxation time T1, and the spin-spin relaxation time T2. The extent to which the signal is weighted toward one or several parameters is related to the history of the spin system preceding detection. On the simplifying, though not generally warranted assumption that the spin density does not vary significantly in soft tissues, relative tissue contrast can be predicted quantitatively provided the relaxation times are known. Signal intensities and contrast were computed on the basis of the Bloch equations and experimentally determined relaxation times as a function of pulse timing parameters and the data compared with those in images recorded at 0.5T field strength. Significant deviations from the equal density hypothesis were found for gray and white substance. Notably partial saturation but also spin echo and inversion-recovery images are not in full accordance with predictions made on the basis of relaxation times alone.

Full Text

Cited Authors

  • Wehrli, FW; MacFall, JR; Glover, GH; Grigsby, N; Haughton, V; Johanson, J

Published Date

  • January 1, 1984

Published In

Volume / Issue

  • 2 / 1

Start / End Page

  • 3 - 16

PubMed ID

  • 6530915

Pubmed Central ID

  • 6530915

Electronic International Standard Serial Number (EISSN)

  • 1873-5894

International Standard Serial Number (ISSN)

  • 0730-725X

Digital Object Identifier (DOI)

  • 10.1016/0730-725x(84)90119-x


  • eng