PT  - JOURNAL ARTICLE
AU  - van Waesberghe, J H
AU  - van Walderveen, M A
AU  - Castelijns, J A
AU  - Scheltens, P
AU  - Lycklama à Nijeholt, G J
AU  - Polman, C H
AU  - Barkhof, F
TI  - Patterns of lesion development in multiple sclerosis: longitudinal observations with T1-weighted spin-echo and magnetization transfer MR.
DP  - 1998 Apr 01
TA  - American Journal of Neuroradiology
PG  - 675--683
VI  - 19
IP  - 4
4099  - http://www.ajnr.org/content/19/4/675.short
4100  - http://www.ajnr.org/content/19/4/675.full
SO  - Am. J. Neuroradiol.1998 Apr 01; 19
AB  - 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.