Patterns of lesion development in multiple sclerosis: longitudinal observations with T1-weighted spin-echo and magnetization transfer MR

J H van Waesberghe, M A van Walderveen, J A Castelijns, P Scheltens, G J Lycklama à Nijeholt, C H Polman, F Barkhof

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PURPOSE: We evaluated the appearance of enhancing multiple sclerosis (MS) lesions on unenhanced T1-weighted MR images and the natural course of enhancing MS lesions on serial unenhanced T1-weighted and magnetization transfer (MT) MR images.

METHODS: One hundred twenty-six enhancing lesions were followed up monthly for 6 to 12 months to determine their signal intensity on unenhanced T1-weighted and MT MR images. At the time of initial enhancement, the size of the lesion and the contrast ratio of enhancement were calculated for each enhancing lesion. During follow-up, the contrast ratio on the corresponding unenhanced T1-weighted image was measured, and an MT ratio (MTR) was calculated.

RESULTS: Twenty-five enhancing lesions (20%) appeared isointense and 101 lesions (80%) appeared hypointense relative to normal-appearing white matter on unenhanced T1-weighted images. During 6 months of follow-up, four MR patterns of active lesions were detected: initially isointense lesions remained isointense (15%); initially isointense lesions became hypointense (5%, most of which reenhanced); initially hypointense lesions became isointense (44%); and initially hypointense lesions remained hypointense (36%). MTR was significantly lower for hypointense lesions as compared with isointense lesions at the time of initial enhancement. For lesions that changed from hypointense to isointense, MTR increased significantly during 6 months of follow-up. Multiple regression analysis showed that strongly decreased MTR at the time of initial enhancement and enhancement duration of more than one scan were predictive of a hypointense appearance on unenhanced T1-weighted images at 6 months' follow-up. Ring enhancement was found to be the only (weak) predictor of persistently hypointense signal intensity.

CONCLUSION: Most enhancing lesions appear slightly to significantly hypointense on unenhanced T1-weighted images. Although most hypointensities are reversible, only those lesions that fail to recover on unenhanced T1-weighted and MT images may have considerable irreversible structural changes.

Original languageEnglish
Pages (from-to)675-83
Number of pages9
JournalAmerican journal of neuroradiology
Issue number4
Publication statusPublished - Apr 1998


  • Adolescent
  • Adult
  • Brain/pathology
  • Disease Progression
  • Female
  • Follow-Up Studies
  • Humans
  • Longitudinal Studies
  • Magnetic Resonance Imaging/methods
  • Male
  • Multiple Sclerosis/classification
  • Recurrence
  • Time Factors

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