th  - 1988 - 51st ENC Conference

1 0 6 I AR'nFACT'3 IN ECHO-PLANAR IMAGING
Hector E. Avram * 1), Lawrence E. Crooks 2) and David M. Kramer 1)
1) Diasonics MRI, 533 Cabot Rd., South San Francisco, CA 94080
2) University of California, San Francisco, 400 Grandview Dr., South San Francisco, CA 94080
Since its introduction in 1978 (1), Echo-Planar imaging has developed into a real clinical posibility for
imaging of the human body when very high speed is required as in the case of uncooperative patients and
children (2). Echo-Planar allows acquisition of an entire image in a time under 0.1 sec.. This technique is
based on the use of succesive gradient-recalled echoes, individually phase encoded, to generate a 2DFT
image. By switching readout gradient polarity, phase distortions occur which generate image artifacts
mainly a ghost image L/2 away from the primary image (where L is the y-image dimension). It is found that
these phase distortions which arise mainly from magnetic field inhomogeneities, gradient instabilities and
eddy current distributions, are to a certain extent predictable and that with proper zero and first order
phasing of the echoes such artifacts are minimized if not eliminated.
A scheme for an efficient way to phase correct the phase encoded projections will be presented.
(1) Mansfield P, Pykett IL, J Magn Reson 1978; 29:355-373
(2) Crooks LE, et al, Radiology 1988;166:157-163
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'I~VO DIMENSIONAL NMR SOFTWARE IN THE
WORKSTATION ENVIRONMENT
Frank Delaglio °, Pascale Sole1", Hans Grahnl", Alex Macur,
John Begemann, Molly Crowther, Roy Hoffmanl", and George C. Levy.
New Methods Research, Inc., 719 East Genesee Street, Syracuse, NY 13210.
We present several techniques for optimal analysis of 2D NMR spectra, which rely both on the
computational power and advanced graphics capabilities of modern scientific workstations. Examples
include methods from the field of image processing, such as morphological filters, histogram
equalizations, and various segmentation procedures. Such techniques, which improve data visibility,
are most valuable when results can be obtained and examined quickly in an interactive scheme.
Other examples involve surface fitting of 2D spectra, a task which is of course computationally
strenuous, but also benefits from flexible graphics for presentation and evaluation of results. We use
surface fitting to compensate for baseplane distortions, measure 2D NOE peak volumes, and to
simulate DQF-COSY crosspeak multiplets.
An outline of other methods newly implemented in the NMR2 two dimensional NMR software
system is presented, including interactive bicomplex 2D phasing, 2D solvent signal subtraction, and
connectivity analysis. We also illustrate our first-generation implementations for 3D NMR processing
and presentation.
"~ NMR and Data Processing Laboratory, NIH Resource and CASE Center, Syracuse University,
Syracuse, NY 13244-1200.
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