Radiology, Vol 160, 375-381, Copyright © 1986 by Radiological Society of North America
T2 estimates in healthy and diseased brain tissue: a comparison using various MR pulse sequences
RH Darwin, BP Drayer, SJ Riederer, HZ Wang and JR MacFall
Fourteen patients and five healthy individuals underwent magnetic resonance
(MR) imaging to determine an effective multiple spin echo pulse sequence
for estimating T2. Lesions examined included infarction, glioma, multiple
sclerosis, and acute hematoma. A pulse repetition time (TR) of 1,500 msec
and echo delays (TEs) of 25, 50, 75, and 100 msec were used. Computed T2
images were derived from all four echoes, the first two echoes, and the
first and fourth echoes. T2 values were obtained from specific brain
locales using region-of-interest analysis. Use of either the first two
echoes or the first and fourth in the T2 fit provided T2 estimates which
closely correlated with that of the four-echo analysis. The noise level in
T2 maps constructed from the 25- and 100-msec echoes was modestly
(typically 10%) higher than that from four echoes; noise level from the 25-
and 50-msec echoes was markedly higher, typically 60%. This behavior is
remarkably consistent with that predicted from theory. All 19 subjects
displayed consistent relative T2 values for specific brain structures; in
13, the absolute T2 values fell within a limited range. Despite the high
sensitivity of T2 images, their specificity in the detection of most brain
disease appears limited except in acute intracerebral hematoma, which
exhibited a decreased T2 relaxation time using high-field-strength MR
imaging.
