title: The evaluation of MRI diffusion values of active demyelinating lesions in multiple sclerosis.
abstract: BACKGROUND
  Gadolinium (Gd) enhancement of lesions is the main radiologic marker for detection of activity in Multiple Sclerosis (MS). This study compares Diffusion weighted imaging (DWI) characteristics and enhancement to determine whether DWI can be used as an alternative to Gd administration.
  
  
  METHODS
  A retrospective study of 72 patients who had MRI with Gd and DWI. Visual assessment and comparison of the Apparent Diffusion Coefficient (ADC) values on Gd+ lesions, all lesions showing restricted diffusion, 2 Gd- lesions and 1 area of normal-appearing white matter (NAWM) in each MRI were performed.
  
  
  RESULTS
  DWI values were measured on 275 T2 lesions, 68 Gd+ and 207 Gd- lesions, as well as 104 NAWM. 34 Gd+ lesions showed restricted diffusion. The median ADC-minimum of Gd+ lesions was significantly lower than NAWM and even lower than Gd- lesions. Most DWI restricted lesions were also Gd+(specificity≥94%), however many Gd+ lesions did not show visually detectable restriction in DWI (sensitivity≤34%). The median ADC-minimum of symptomatic lesions was lower than asymptomatic lesions.
  
  
  CONCLUSIONS
  While Gd+ lesions have lower ADC-minimum, visual DWI assessment cannot replace Gd administration for identifying active lesions. Gd+ lesions showing restricted diffusion are clinically important as they are more likely associated with neurological symptoms.
authors.affiliation: University of Ottawa, Canada. Electronic address: drmabdoli@gmail.com.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Abdoli
authors.affiliation: Department of Radiology, University of Ottawa, Department of Medical Imaging, The Ottawa Hospital, Canada. Electronic address: schakraborty@toh.ca.
authors.forename: Santanu
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Ottawa Hospital, General Campus, University of Ottawa, Canada. Electronic address: hmaclean@toh.on.ca.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: MacLean
authors.affiliation: The Ottawa Hospital Research Institute and the University of Ottawa, Canada. Electronic address: MFREEDMAN@toh.ca.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Freedman
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004185:Disability Evaluation; D005260:Female; D005682:Gadolinium; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D005682:Gadolinium
keywords: Detection of new MRI activity; Diffusion magnetic resonance imaging; Gadolinium; Magnetic resonance imaging; Multiple sclerosis; Restricted diffusion