American Journal of Roentgenology, Vol 165, 963-966, Copyright © 1995 by American Roentgen Ray Society
MR imaging of diseases of the brain: comparison of GRASE and conventional spin-echo T2-weighted pulse sequences
MR Patel, RA Klufas and AW Shapiro
Department of Radiology, Beth Israel Hospital, Boston, MA 02215, USA.
OBJECTIVE. The purpose of this study was to compare a combined gradient and
spin-echo (GRASE) technique, which is a rapid T2-weighted imaging sequence,
with conventional spin-echo (SE) sequences for imaging brain lesions. The
GRASE sequences would allow increased patient throughput with potential
cost savings and be useful in uncooperative patients without requiring
echoplanar imaging techniques and specialized hardware. SUBJECTS AND
METHODS. Conventional SE and GRASE T2-weighted images of 49 consecutive
patients (20-86 years old) were reviewed independently by three
neurora-diologists for the presence and characterization of lesions (most
of which were nonspecific foci of hyperintensity within the white matter),
gray-white matter differentiation, conspicuity of lesions, and
periventricular signal abnormality. The MR studies were performed on a
1.0-T Siemens Magnetom Impact scanner, with the SE images obtained using a
TR/TE of 2400/40 and the GRASE images obtained using a TR/effective TE of
4400/110. RESULTS. The number of lesions detected that were 5 mm or larger
in maximal diameter did not significantly differ among techniques. For
lesions smaller than 5 mm, conventional SE T2-weighted images showed more
lesions (p < .01). The SE images were better than the GRASE images for
assessing gray-white matter differentiation, conspicuity of lesions, and
periventricular signal abnormality. The two hypointense lesions were better
assessed on the conventional SE images. CONCLUSION. Although GRASE imaging
may be potentially useful for rapid imaging of the brain, our experience
shows it has a markedly diminished sensitivity for detecting lesions
smaller than 5 mm in diameter. Currently, GRASE imaging should not replace
the routine clinical use of conventional SE sequences.