Radiology, Vol 155, 731-738, Copyright © 1985 by Radiological Society of North America
Synthesized MR images: comparison with acquired images
SA Bobman, SJ Riederer, JN Lee, SA Suddarth, HZ Wang and JR MacFall
Synthesized and directly acquired spin-echo images were compared in order
to assess the validity of magnetic resonance (MR) image synthesis as a
method enabling retrospective formation of images by interactive
manipulation of scan parameters. Synthetic images subjectively compared
favorably in both accuracy and precision with acquired images when formed
for the same values of echo (TE) and repetition times (TR) and for
interpolated and extrapolated values of both TE and TR. Plots of synthetic
and acquired signals within the same pixel sectors quantitatively showed
comparable values for several regions of interest in the brain. Percent
error and noise-normalized differences between acquired and synthetic
images were tested as a quantitative measure of accuracy. Percent error was
consistently less than 5% for brain parenchyma, and synthetic signals were
accurate to within four times the noise level at acquisition. The apparent
signal-to-noise ratio of synthetic images was comparable, superior, or
inferior to similar acquired images, depending on the values of TE and TR.
Total acquisition time required for synthetic formation of images for
arbitrary values of TE and TR was equivalent to that of a single direct
acquisition with a TR of 2,500 msec.
