Increased spatial resolution using a three-dimensional T1-weighted gradient-echo MR sequence results in greater hypointense lesion volumes in multiple sclerosis.
OBJECTIVE
Our goal was to evaluate whether improved spatial resolution of MR images results in the detection of higher volumes of hypointense lesions in patients with multiple sclerosis (MS).


METHODS
A magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) sequence with subsequent reconstruction of axial sections with 5-, 3-, and 1-mm thickness and a dual-echo sequence were obtained in 16 patients with relapsing-remitting or secondary-progressive MS. The volumes of MR imaging abnormalities present on each of these studies were measured using a semiautomated segmentation technique based on local thresholding. The hypointense lesion volumes seen on the three reconstructed MP-RAGE sets of images were compared using the Friedman test and correlated with the hyperintense lesion volume on proton density-weighted images and with scores on the Expanded Disability Status Scale using Spearman's rank correlation coefficient.


RESULTS
The median volume of hypointense lesions increased from 1.2 mL (range, 0 to 14.9 mL) on the 5-mm-thick MP-RAGE images to 1.7 mL (range, 0 to 15.8 mL) on the 3-mm-thick images, and to 1.9 mL (range, 0 to 16.2 mL) on the 1-mm-thick images. The hypointense lesion volumes measured on the three MP-RAGE images correlated significantly with the degree of disability, whereas this correlation was not significant with the T2-weighted lesion load.


CONCLUSIONS
Our findings indicate that a significant increase in the volume of potentially disabling MS lesions is observed when obtaining MR images with thin sections.
Filippi
M
M
Department of Neurology, Scientific Institute Ospedale San Raffaele, University of Milan, Italy.
Rocca
M A
MA
Horsfield
M A
MA
Rovaris
M
M
Pereira
C
C
Yousry
T A
TA
Colombo
B
B
Comi
G
G
D000328:Adult; D001921:Brain / Q000473:pathology*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D009103:Multiple Sclerosis / Q000175:diagnosis*; D012680:Sensitivity and Specificity