During 1992-2000 authors found a ring - enhancing sign on CT scans and MRI in 81 patients with neoplasms, brain infections, including parasitic affections and in patients with clinically confirmed multiple sclerosis. They found a closed ring in all patients with neoplasms and infections (including parasitic disease). In most patients with clinically confirmed multiple sclerosis they found an open - ring imaging sign, however in a few cases they found in addition to a periventricular hyperintensive lesion also a closed ring, that are contrary to open rings not typical for this disease.

        Key words: open ring - closed ring - multiple sclerosis - MRI - CT