Remyelinated lesions in multiple sclerosis: magnetic resonance image appearance.
BACKGROUND
Various types of pathologic mechanisms in multiple sclerosis (MS) can alter magnetic resonance imaging (MRI) signals, and the appearance of remyelinated lesions on MRI is largely unknown.


OBJECTIVE
To describe the MRI appearance of remyelinated lesions in MS.


METHODS
Comparison of postmortem MRI findings with histopathologic findings.


METHODS
Brain donations from a general community. Patients Magnetic resonance images from 36 rapid autopsies yielded 161 areas that could be matched with histologic characteristics, including 149 focal T2-weighted abnormalities, with a range of signal intensities on T1-weighted images. In a subset of 49 lesions, magnetization transfer ratio could be determined.


METHODS
An observer blinded to the MRI findings assessed the presence of remyelination using light microscopic criteria; in 25 areas, in situ hybridization was used to assess the presence of oligodendrocytes expressing proteolipid protein messenger RNA.


RESULTS
Remyelinated areas were found in 67 lesions (42%): partial remyelination was present in 30 lesions (19%), whereas 37 lesions (23%) were fully remyelinated. Remyelinated lesions contained enhanced numbers of oligodendrocytes containing proteolipid protein messenger RNA. All areas with remyelination shown histopathologically were hyperintense on T2-weighted images. Strong hypointensity on T1-weighted images was significantly associated (chi2 = 29.8, P<.001) with demyelinated and partially remyelinated lesions compared with fully remyelinated lesions. The magnetization transfer ratio of remyelinated lesions (mean [SD], 27.6% [41%]) differed (F = 46.3, P<.001) from both normal-appearing white matter (35.2% [32%]) and demyelinated lesions (22.3% [48%]).


CONCLUSIONS
Remyelinated lesions return an abnormal signal on T2-weighted images. Both T1-weighted images and magnetization transfer ratio may have (limited) additional value in separating lesions with and without remyelination.
Barkhof
Frederik
F
Dutch MR-MS Center, and Department of Radiology, Vrije Universiteit Medical Center, PO Box 7057, 1007 MB Amsterdam, the Netherlands. f.barkhof@vumc.nl
Bruck
Wolfgang
W
De Groot
Corline J A
CJ
Bergers
Elisabeth
E
Hulshof
Sandra
S
Geurts
Jeroen
J
Polman
Chris H
CH
van der Valk
Paul
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009019:Morphinans / Q000032:analysis; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D018991:Myelin Proteolipid Protein / Q000378:metabolism; D009186:Myelin Sheath / Q000473:pathology; D011859:Radiography
D009019:Morphinans; D018991:Myelin Proteolipid Protein; C013757:Mr 1257 MS