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RT Journal Article
SR Electronic
T1 Multiparametric Characterization and Spatial Distribution of Different MS Lesion Phenotypes
JF American Journal of Neuroradiology
JO Am. J. Neuroradiol.
FD American Society of Neuroradiology
SP 1166
OP 1174
DO 10.3174/ajnr.A8271
VO 45
IS 8
A1 Tazza, Francesco
A1 Boffa, Giacomo
A1 Schiavi, Simona
A1 Lapucci, Caterina
A1 Piredda, Gian Franco
A1 Cipriano, Emilio
A1 Zacà, Domenico
A1 Roccatagliata, Luca
A1 Hilbert, Tom
A1 Kober, Tobias
A1 Inglese, Matilde
A1 Costagli, Mauro
YR 2024
UL http://www.ajnr.org/content/45/8/1166.abstract
AB BACKGROUND AND PURPOSE: MS lesions exhibit varying degrees of axonal and myelin damage. A comprehensive description of lesion phenotypes could contribute to an improved radiologic evaluation of smoldering inflammation and remyelination processes. This study aimed to identify in vivo distinct MS lesion types using quantitative susceptibility mapping and susceptibility mapping–weighted imaging and to characterize them through T1-relaxometry, myelin mapping, and diffusion MR imaging. The spatial distribution of lesion phenotypes in relation to ventricular CSF was investigated.MATERIALS AND METHODS: MS lesions of 53 individuals were categorized into iso- or hypointense lesions, hyperintense lesions, and paramagnetic rim lesions, on the basis of their appearance on quantitative susceptibility mapping alone, according to published criteria, and with the additional support of susceptibility mapping–weighted imaging. Susceptibility values, T1-relaxation times, myelin and free water fractions, intracellular volume fraction, and the orientation dispersion index were compared among lesion phenotypes. The distance of the geometric center of each lesion from the ventricular CSF was calculated.RESULTS: Eight hundred ninety-six MS lesions underwent the categorization process using quantitative susceptibility mapping and susceptibility mapping–weighted imaging. The novel use of susceptibility mapping–weighted images, which revealed additional microvasculature details, led us to re-allocate several lesions to different categories, resulting in a 35.6% decrease in the number of paramagnetic rim lesions, a 22.5% decrease in hyperintense lesions, and a 17.2% increase in iso- or hypointense lesions, with respect to the categorization based on quantitative susceptibility mapping only. The outcome of the categorization based on the joint use of quantitative susceptibility mapping and susceptibility mapping–weighted imaging was that 44.4% of lesions were iso- or hypointense lesions, 47.9% were hyperintense lesions, and 7.7% were paramagnetic rim lesions. A worsening gradient was observed from iso- or hypointense lesions to hyperintense lesions to paramagnetic rim lesions in T1-relaxation times, myelin water fraction, free water fraction, and intracellular volume fraction. Paramagnetic rim lesions were located closer to ventricular CSF than iso- or hypointense lesions. The volume of hyperintense lesions was associated with a more severe disease course.CONCLUSIONS: Quantitative susceptibility mapping and susceptibility mapping–weighted imaging allow in vivo classification of MS lesions into different phenotypes, characterized by different levels of axonal and myelin loss and spatial distribution. Hyperintense lesions and paramagnetic rim lesions, which have the most severe microstructural damage, were more often observed in the periventricular WM and were associated with a more severe disease course.ARMSSAge-Related MS Severity ScoreEDSSExpanded Disability Status ScaleFWFfree water fractionHChealthy controlHYPERhyperintense lesionsISO-HYPOiso- or hypointense lesionsICVFintracellular volume fractionMWFmyelin water fractionODIorientation dispersion indexPRLparamagnetic rim lesionQSMquantitative susceptibility mappingSMWIsusceptibility mapping–weighted imaging