Magnetic resonance outcome of new enhancing lesions in patients with relapsing-remitting multiple sclerosis.

The aim of the study was to monitor the natural history of new enhancing lesions in multiple sclerosis (MS) by means of serial gadolinium-enhanced magnetic resonance imaging (MRI). Out of the 63 new enhancing lesions seen on the baseline scan, belonging to 26 relapsing-remitting MS patients, 26 (40\%), nine (14\%) and four (6\%) lesions showed persisting enhancement at first, second and third follow-up scan, respectively. At the end of 5 months of follow-up, 58 (92\%) of the new enhancing lesions were detected as T2 hyperintensities, 24 (38\%) as T1 hypointensities ('black holes'), and five lesions (8\%) disappeared in both T2 and T1 weighted images. Duration of gadolinium enhancement of at least two consecutive scans significantly influenced the development of 'black holes'. No significant correlation was observed between volume, location, configuration of enhancement at baseline and final outcome of the lesion. In individual cases, different evolution of new enhancing lesions was observed at the same time. In conclusion, this study documented that different outcomes of new lesions are unrelated either to the individual patient or to the baseline MRI characteristics. However, prolonged blood-brain-barrier disruption as shown by persisting enhancement significantly influences the lesion outcome.