American Journal of Roentgenology, Vol 173, 479-485, Copyright © 1999 by American Roentgen Ray Society
Echoplanar MR imaging for ultrafast detection of brain lesions
MR Patel, B Siewert, R Klufas, N Yousuf, RR Edelman and S Warach
Department of Radiology, SCC, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
OBJECTIVE: We retrospectively evaluated the use of echo-planar imaging for
ultrafast detection of brain lesions. MATERIALS AND METHODS: In our
retrospective study, 61 patients were imaged with the following echo-
planar sequences: single-shot proton density-weighted, single-shot T2-
weighted, single-shot T2-weighted high-resolution, multishot proton
density-weighted, and multishot T2-weighted. Lesions revealed in these
patients ranged from 0.5 to 12.0 cm (mean, 3.7 cm) and were the result of
tumor (n = 16), stroke (n = 21), demyelination (n = 18), and toxoplasmosis
(n = 2). Four patients had scans with normal findings. Two
neuroradiologists who were unaware of pertinent clinical data reviewed the
images. The images were retrospectively compared with conventional
spin-echo images for diagnosis, sensitivity of lesion detection, and
qualitative criteria: subjective image quality, gray and white matter
differentiation, lesion conspicuity, delineation of lesion borders, and
artifacts. (Artifacts included those caused by motion, susceptibility,
pulsation, and ghosting.) Quantitative criteria, including signal-to-noise
and signal difference-to-noise measurements, were also evaluated in 40
lesions. RESULTS: Sensitivity for lesion detection was 97% for single-shot
echo-planar T2-weighted MR images and 100% for multishot echo-planar
T2-weighted MR images. Single-shot echo- planar proton density-weighted MR
images had the highest signal-to- noise ratio (91.2+/-19.3). Echo-planar
T2-weighted MR images had the highest signal difference-to-noise
(33.8+/-22.9). Echo-planar sequences were superior to spin-echo sequences
regarding motion and pulsation artifacts. Spin-echo sequences lacked
susceptibility and ghosting artifacts, and were superior in lesion
conspicuity and delineation of lesion borders. CONCLUSION: In this study,
echo-planar sequences were as sensitive as conventional spin-echo imaging
for the diagnostic assessment of lesions. Echo-planar sequences had a
strikingly shorter acquisition time and substantially reduced motion and
pulsation artifacts. Echo-planar sequences may be a useful diagnostic tool
for use in claustrophobic and unstable patients.