COBALT-55 POSITRON EMISSION TOMOGRAPHY IN RELAPSING-PROGRESSIVE MULTIPLE-SCLEROSIS

Multiple sclerosis (MS) is an immune-mediated disease of the white mat ter in the brain that can have a progressive course. However, the prog ression of relapsing-remitting (RR) MS into relapsing-progressive (RP) MS might represent a more fundamental change in disease activity, i.e . decay of vulnerable neurons and oligodendrocytes. In RP-MS, this may imply that the major loss of brain tissue structure is caused by a co mbination of demyelination and cellular loss, both of which are likely to cause disability in MS. We used the PET isotope cobalt-55 (Go) as a calcium (Ca) tracer to visualize brain tissue damage, based on the f act that Ca influx is essential in both cell death and T-lymphocyte ac tivation in MS. The aim of this study was to determine whether Co-PET detects any RP-MS lesions and, if so, to assess any correlation with t he progression rate (PR) of the disease and with MS lesions as detecte d by MRI. Seven RP-MS patients (Poser) with EDSS > 4.0 (Kurtzke) and 7 healthy controls underwent MRI (Miller, Barkhof) and Co-PET. Comparis on of both image modalities was made by merging. Co-PET lesion frequen cy was assessed and correlated with the PR of the disease. Co-PET demo nstrated significantly more lesions in the MS brain than in the health y brain, both periventricular and cortical. Every single MRI lesion co uld be retrieved as a Co-PET lesion. The Co-PET lesion frequency corre lated significantly with PR. Our pilot study possibly suggests Co-PET as a tool in estimating disease activity in RP-MS. Validation of metho d in a larger patient group (RP-MS vs PR-MS vs healthy controls) will be necessary.