The Role of Susceptibility Weighted Imaging as a Substitute to Post-Contrast Tl-Weighted Images in Detection of Active Multiple Sclerosis Lesions

Abstract Background And Purpose Multiple sclerosis (MS) is a progressive inflammatory, demyelinating, autoimmune disease of the central nervous system (CNS). Its inflammatory process is thought to be initiated and maintained by an autoimmune cascade, leading to the accumulation of focal perivascular infiltrates of mononuclear inflammatory cells, microglia activation, demyelination, and axonal degeneration. Acute inflammatory activity of MS lesions is traditionally assessed through contrast-enhanced Tl- weighted MR images. Yet, the use of contrast is contraindicated in some patients. However, SWI may represent a viable alternative to contrast agents for this purpose. Aim The aim of this study is to determine whether a qualitative evaluation of SWI can be used to distinguish active and inactive MS lesions and whether it could be considered as a feasible alternative to gadolinium-based contrast agents for fulfilling this objective. Materials And Methods our study was carried out on 76 Adult patients of either sex with a known diagnosis of MS based on the 2010 revision of the McDonald criteria. SWI &post contrast Tl weighted imaging were recorded and compared. Results The presence of hypointense rings or marked hypointensity showed a strong association with the absence of gadolinium enhancement (P, .001), with a sensitivity of 93.0% and a specificity of 82.9%. The presence of mild hypointensity or isohyperintensity showed a strong association with the presence of gadolinium enhancement (P, .001), with a sensitivity of 68.3% and a specificity of 99.2%. Conclusions A qualitative analysis of the signal pattern on SWI of T2-hyperintense MS lesions allows determining the likelihood that the lesions will enhance after administration of a gadolinium contrast agent, with high specificity albeit with a moderate sensitivity. While it cannot substitute for the use of contrast agent, it can be useful in some clinical settings in which the contrast agent cannot be administered.