title: Increased spatial resolution using a three-dimensional T1-weighted gradient-echo MR sequence results in greater hypointense lesion volumes in multiple sclerosis.
abstract: 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.
authors.affiliation: Department of Neurology, Scientific Institute Ospedale San Raffaele, University of Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Filippi
authors.forename: M A
authors.initials: MA
authors.lastname: Rocca
authors.forename: M A
authors.initials: MA
authors.lastname: Horsfield
authors.forename: M
authors.initials: M
authors.lastname: Rovaris
authors.forename: C
authors.initials: C
authors.lastname: Pereira
authors.forename: T A
authors.initials: TA
authors.lastname: Yousry
authors.forename: B
authors.initials: B
authors.lastname: Colombo
authors.forename: G
authors.initials: G
authors.lastname: Comi
mesh_terms: 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