title: Diffusion-tensor MR imaging of corticospinal tract in amyotrophic lateral sclerosis and progressive muscular atrophy.
abstract: OBJECTIVE
  To prospectively evaluate several diffusion-tensor magnetic resonance (MR) imaging indexes (mean diffusivity [MD], fractional anisotropy [FA], and eigenvalues) of corticospinal tract impairment in patients with progressive muscular atrophy (PMA) and patients with amyotrophic lateral sclerosis (ALS).
  
  
  METHODS
  This study had institutional review board approval, and written informed consent was obtained from all subjects. Eight male patients with PMA (mean age, 63 years +/- 13 [standard deviation]), eighteen patients with ALS (14 men and four women; mean age, 64 years +/- 7), and twelve control subjects (four men and eight women; mean age, 65 years +/- 6) underwent diffusion-tensor MR imaging at which 25 spin-echo echo-planar imaging diffusion-weighted images (b = 1000 sec/mm2) were acquired along noncollinear directions. MD and FA were measured along the corticospinal tracts in each patient and subject. Changes in diffusion along and orthogonal to fiber bundles in patients were evaluated by using diffusion-tensor eigenvalues. Differences in diffusion-tensor imaging indexes between patients with PMA and those with ALS, as compared with these indexes in control subjects, were evaluated with Mann-Whitney testing. Correlations between diffusion-tensor imaging indexes and clinical variables were estimated with Pearson and Spearman rank correlation testing.
  
  
  RESULTS
  As compared with MD (697.1 x 10(-6) mm2/sec +/- 28.1) and FA (0.585 +/- 0.032) in control subjects, MD was typically significantly increased (734.7 x 10(-6) mm2/sec +/- 41.2, P = .035) and FA significantly decreased (0.534 +/- 0.053, P = .037) along the corticospinal tracts in patients with ALS, while these parameters showed no significant change in patients with PMA (MD, 707.0 x 10(-6) mm2/sec +/- 44.2; FA, 0.559 +/- 0.028). Estimation of diffusion-tensor eigenvalues revealed normal diffusion along fiber tracts in all patients, while diffusion was increased orthogonal to fiber tracts only in patients with typical ALS. In patients with ALS, MD correlated with disease duration while FA correlated with disease severity.
  
  
  CONCLUSIONS
  Diffusion-tensor MR imaging reveals corticospinal tract impairment in ALS but not in PMA.
authors.affiliation: Department of Neuroscience, University of Pisa, via Roma 67, 56100 Pisa, Italy. mircocosottini@libero.it
authors.forename: Mirco
authors.initials: M
authors.lastname: Cosottini
authors.forename: Marco
authors.initials: M
authors.lastname: Giannelli
authors.forename: Gabriele
authors.initials: G
authors.lastname: Siciliano
authors.forename: Guido
authors.initials: G
authors.lastname: Lazzarotti
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Michelassi
authors.forename: Alberto
authors.initials: A
authors.lastname: Del Corona
authors.forename: Carlo
authors.initials: C
authors.lastname: Bartolozzi
authors.forename: Luigi
authors.initials: L
authors.lastname: Murri
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis*; D016880:Anisotropy; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009134:Muscular Atrophy, Spinal / Q000175:diagnosis*; D011712:Pyramidal Tracts / Q000473:pathology*