Detection of Active Plaques in Multiple Sclerosis using Susceptibility-weighted Imaging: Comparison with Gadolinium-enhanced MR Imaging

Abstract

Purpose: Susceptibility-weighted (SW) imaging is a magnetic resonance (MR) imaging technique reported effective in visualizing multiple sclerosis (MS) plaques, but its capacity to distinguish active plaques remains unclear. We evaluated active plaque detection by SW compared with contrast-enhanced MR imaging.
Methods: We prospectively examined 11 patients using a 3-tesla scanner. Two neuroradiologists independently evaluated signal changes of plaques and accompanying low signal rims in 74 plaques on various SW images (magnitude, phase, and minimum intensity projection [minIP]), and on contrast-enhanced T₁-weighted images (T₁WI). We correlated signal alterations on various SW images and contrast enhancement on T₁WI using Fisher's exact test and calculated sensitivity and specificity for predicting gadolinium enhancement.
Results: Only changes in plaque signal on SW magnitude images correlated significantly with contrast enhancement of the plaques (P=0.008), and high signal intensity had 0.556 sensitivity and 0.787 specificity for predicting contrast-enhanced plaques. Furthermore, plaques with rims of low signal showed sensitivity of 0.296 and specificity of 0.957.
Conclusions: Susceptibility-weighted magnitude, but not phase or minIP, images can predict MS plaques with contrast enhancement with high specificity.