Characterization of Multiple Sclerosis Plaques Using Susceptibility-Weighted Imaging at 1.5 T: Can Perivenular Localization Improve Specificity of Imaging Criteria?
purpose of this study was to determine if magnetic resonance (MR)
susceptibility-weighted imaging (SWI) can increase the conspicuity of
corticomedullary veins within the white matter lesions of multiple sclerosis (MS) and, thus, aid in distinguishing plaques from leukoaraiosis.
retrospectively reviewed MR examinations in 21 patients with a clinical
diagnosis of MS and 18 patients with a clinical diagnosis of dementia.
Examinations included fluid-attenuated inversion recovery (FLAIR) and
SWI sequences obtained in the axial plane. Lesions greater than 5 mm in
diameter on the axial FLAIR sequence were identified as periventricular
or subcortical. Three neuroradiologists evaluated SWI images, compared
with FLAIR, for a centrally located signal void in each lesion that was
scored as present, absent, or indeterminate.
patients with MS, central veins were present in both periventricular
lesions (75%, P < 0.001) and subcortical lesions (52%, P < 0.005).
In patients with dementia, central veins were seen much less frequently
in subcortical lesions (14%, P < 0.001); their association with
periventricular lesions was not significant.
veins were detected in MS lesions with a significantly greater
frequency than that in patients with dementia. Susceptibility-weighted
imaging increases the conspicuity of corticomedullary veins and may
improve the specificity of MR findings in MS.
MRI is regularly being used in the diagnostic work-up when MS is suspected, however the current revised “McDonald” criteria, which rely on the size, shape and distribution pattern (“dissemination in time and space”) of lesions in the brain and spinal cord are not entirely fool proof. A recent approach to make MRI more specific to support (or rule out) a diagnosis of MS is based on a histological hallmark of MS lesions: the central vein around which most lesions – certainly in the brain white matter – evolve. This feature, the “central vein sign” (CVS) can be visualised using MRI techniques that are particularly sensitive (“susceptible”) to the iron in haemoglobin in veins. There are several variations on the theme, sometimes combining “lesion scans” (such as T2 or FLAIR) with “iron” scans (for example T2*) to refine the detection of CVS as a new diagnostic tool such as in the example below by Pascal Sati and colleagues in Danny Reich’s group at the NIH/NINDS:
Those attending the BartsMS/UCLP Research Day tomorrow will learn what our team is currently doing to develop the non-invasive histological diagnosis of MS further.