Serial study of gadolinium-DTPA MRI enhancement in multiple sclerosis

While the diagnosis of multiple sclerosis is accomplished on the basis of clinical symptoms, magnetic resonance imaging (MRI) may be far superior for observing the underlying disease process itself. This is especially true for the observation of many multiple sclerosis white matter lesions that do not produce any detectable symptoms at all. In addition, multiple sclerosis is often a fluctuating disease, and both symptoms and lesions wax and wane with time. A study was undertaken to determine if monthly MRI could provide insight into the dynamic pathological processes of multiple sclerosis. The brains of four patients with multiple sclerosis were imaged monthly for a total of four months. In addition to the standard unenhanced MRI, the patients were also imaged using gadolinium-DTPA enhancement. The paramagnetic properties of the metallic element gadolinium can sometimes reveal lesions on the final image that would be difficult to visualize otherwise. The gadolinium-DTPA is administered intravenously, and it is believed that gadolinium enhancement within the brain represents regions where the substance passes easily from the blood into the brain. The blood-brain barrier, which normally restricts the entrance of many substances into the brain, is apparently less effective at these regions; the pathologic process of multiple sclerosis may be tied to alterations in this blood-brain barrier. When the patients' brains were examined, enhancement was observed in new lesions in the white matter and lesions that were enlarging. Enhancement could also be seen in some pre-existing lesions. When images from the succeeding month were compared, only about 30 percent of the enhancing lesions from the previous month continued to enhance. While all of the lesions could be observed without enhancement, it is thought that enhancement indicates pathological activity. Since enhancement was visible in some older lesions, as well as in all new lesions, it seems that MRI without enhancement may underestimate disease activity in the brains of patients with multiple sclerosis. Gadolinium enhancement suggests that even old lesions, which are not obviously changing on unenhanced MRI, may indeed pass through periods of pathological activity. (Consumer Summary produced by Reliance Medical Information, Inc.)