In the current project we endeavour to study CIS patients with inflammatory disease of the central nervous system or early clinical deficit by using cell labelling MR imaging with ultra small superparamagnetic iron oxide particles (USPIO), which specifically label blood-borne macrophages, a key cell population in MS. We hypothesise that number/volume of USPIO (SH U 555 C) enhancement during the first year is a predictive marker for high risk CIS patients at presentation. This hypothesis is in line with recent findings in the animal model of MS, EAE. Secondary measures of this study will include comparison of the USPIO (SH U 555 C) findings with other highly sensitive, but non-specific MR parameters.