Microstructural magnetic resonance imaging of cortical lesions in multiple sclerosis.
BACKGROUND
Pathologic and magnetic resonance imaging (MRI) studies have shown that cortical lesions (CLs) are a frequent finding in multiple sclerosis (MS).


OBJECTIVE
To quantify microstructural damage in CLs and normal appearing (NA) cortex in relapse-onset MS patients at different stages of the disease.


METHODS
Brain double inversion recovery (DIR), diffusion tensor (DT) MRI and 3D T 1-weighted scans were acquired from 35 relapsing-remitting (RR) patients, 23 secondary progressive (SP) patients, 12 benign (B) MS patients and 41 healthy controls (HC). Diffusivity values in CLs, cortex, white matter (WM) lesions and normal-appearing white matter (NAWM) were assessed.


RESULTS
Compared to HC, MS patients had a significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD) in the cortex and NAWM. CLs had higher FA vs HC cortex and vs patients' cortex. Compared to RRMS patients, SPMS patients had higher WM lesion volume, higher MD in the cortex, and more severe damage to the NAWM and WM lesions. Compared to SPMS patients, BMS patients had lower MD and FA of CLs. Damage in other compartments was similar between SPMS and BMS patients. Damage in CLs had a high power to discriminate BMS from SPMS (area under the curve: 79-91%), with high specificity (85%), sensitivity (100%) and accuracy (90%).


CONCLUSIONS
Microstructural imaging features of CLs differ from those of WM lesions and are likely to reflect neuronal damage and microglial activation. The nature and extent of CL damage can be used to help distinguish the different MS clinical phenotypes.
Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan 20132, Italy. m.filippi@hsr.it
M
M
Filippi
P
P
Preziosa
E
E
Pagani
M
M
Copetti
S
S
Mesaros
B
B
Colombo
M A
MA
Horsfield
A
A
Falini
G
G
Comi
H
H
Lassmann
M A
MA
Rocca
D000328:Adult; D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D055815:Young Adult