title: MRI contrast uptake in new lesions in relapsing-remitting MS followed at weekly intervals.
abstract: BACKGROUND
  One of the diagnostic imaging hallmarks of MS is the uptake of IV administered contrast material in new lesions in the brain, signaling blood-brain barrier breakdown and active inflammation. Many clinical drug trials are designed based on the assumption that lesion enhancement on MRI remains visible on average for 1 month. For practical reasons, few serial MRI studies of patients with MS have been performed at intervals shorter than 4 weeks.
  
  
  METHODS
  The authors performed a year-long longitudinal study in 26 patients with relapsing-remitting MS (RRMS), which comprised an initial phase of MRI follow-up at weekly intervals for 8 weeks, followed by imaging every other week for another 16 weeks, and monthly thereafter. They present a quantitative analysis (using a supervised interactive thresholding procedure) of new enhancing lesions appearing during the first 6 weeks in this cohort and evaluated from the time of first detection until enhancement was no longer seen.
  
  
  RESULTS
  The average duration of Gd-DTPA enhancement in individual new lesions was 3.07 weeks (median, 2 weeks). Significant correlations were demonstrated between the duration of contrast enhancement or initial growth rates and lesion volumes. Different lesions in the same patient appeared to develop largely independent of each other and demonstrated a large range in the duration of enhancement during the acute phase of their evolution.
  
  
  CONCLUSIONS
  The average duration of blood-brain barrier impairment in RRMS is shorter than earlier estimates. Early lesion growth parameters may predict final lesion size. Within-patient heterogeneity of lesion evolution suggests that individual lesions develop independently.
authors.affiliation: Department of Radiology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Francois
authors.initials: F
authors.lastname: Cotton
authors.forename: Howard L
authors.initials: HL
authors.lastname: Weiner
authors.forename: Ferenc A
authors.initials: FA
authors.lastname: Jolesz
authors.forename: Charles R G
authors.initials: CR
authors.lastname: Guttmann
mesh_terms: D000328:Adult; D001812:Blood-Brain Barrier / Q000503:physiopathology; D003287:Contrast Media / Q000493:pharmacokinetics*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D012008:Recurrence; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA