title: Magnetic resonance frequency shifts during acute MS lesion formation.
abstract: OBJECTIVE
  We investigated the evolution of new multiple sclerosis (MS) lesions over time using frequency shifts of the magnetic resonance (MR) signal.
  
  
  METHODS
  Twenty patients with relapsing-remitting MS were serially scanned for 6 months at 1-month intervals. Maps of MR frequency shifts were acquired using susceptibility-weighted imaging. New lesions were identified by enhancement with gadolinium (Gd).
  
  
  RESULTS
  Forty new lesions were identified as areas of signal increase on Gd-enhanced scans. Up to 3 months before lesion appearance, the frequency in areas of future Gd enhancement was not detectably different from the frequency in normal-appearing white matter. Rapid increase in MR frequency was observed between 1 month before and 1 month after Gd enhancement. Two months postenhancement and later, the frequency stabilized and remained at a constantly increased level.
  
  
  CONCLUSIONS
  These findings suggest that an increase in MR frequency does not simply reflect blood-brain barrier disruption or edema; rather, it reflects a change of tissue architecture as a consequence of new lesion formation. The data demonstrate that the MR frequency of focal MS lesions is increased before the lesions appear on conventional MRI. Unlike many other advanced imaging techniques, the images for frequency mapping can be rapidly acquired at high spatial resolution and standardized on most clinical scanners.
authors.affiliation: UBC MRI Research Centre, University of British Columbia, Vancouver, Canada.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Wiggermann
authors.forename: Enedino
authors.initials: E
authors.lastname: Hernández Torres
authors.forename: Irene M
authors.initials: IM
authors.lastname: Vavasour
authors.forename: G R Wayne
authors.initials: GR
authors.lastname: Moore
authors.forename: Cornelia
authors.initials: C
authors.lastname: Laule
authors.forename: Alex L
authors.initials: AL
authors.lastname: MacKay
authors.forename: David K B
authors.initials: DK
authors.lastname: Li
authors.forename: Anthony
authors.initials: A
authors.lastname: Traboulsee
authors.forename: Alexander
authors.initials: A
authors.lastname: Rauscher
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D003287:Contrast Media; D018450:Disease Progression; D005260:Female; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology*
chemical_list: D003287:Contrast Media; D005682:Gadolinium