Gadolinium-DTPA Enhanced MRI in Multiple Sclerosis: A New Method to Monitor Disease Activity and Treatment Efficacy

Abstract

There is no doubt that MRI is the best imaging modality in the diagnosis of multiple sclerosis. As a result of its high sensitivity in the depiction of clinically silent lesions in the brain and the spinal cord it can help to fulfil the criterion of dissemination in space and to establish a definite diagnosis of MS in patients with clinical signs and symptoms pointing at only one location in the CNS. While this diagnostic support provided by MRI is only needed in a minority of MS patients, the possibility of monitoring disease evolution by MRI is becoming increasingly important. Especially in therapeutic studies the use of serial MRI is going to become an indispensable addition to thorough clinical monitoring. But serial MRI scans have also shown that lesions, once appearing, tend to remain rather stable over time with only minor fluctuations in size. Lesions which have not changed in serial MRI, have no specific features which clearly differentiates them from other lesions which have just appeared. Thus, conventional unenhanced MRI gives us a reliable information about the “plaque burden” which has accumulated in MS patients over the years but is not able to show us the degree of actual disease activity. From neuropathological observations and the data available from acute and chronic experimental autoimmune encephalomyelitis we know that a local disruption of the blood brain barrier occurs at an early stage in the development of new lesions. Like CT contrast agents, Gadolinium DTPA accumulates temporarily only in regions with disturbed blood brain barrier. Its use enables us to depict blood brain barrier disturbances and to visualize a certain phase in the evolution of MS-lesions.