Multiple sclerosis: interobserver agreement in reporting active lesions onserial brain MRI using conventional spin echo, fast spin echo, fast fluid-attenuated inversion recovery and post-contrast T1-weighted images

Previous studies have addressed the question of the precision in assessing multiple sclerosis (MS) activity by counting enhancing lesions on gadoliniu m enhanced brain magnetic resonance imaging (MRI). However, counting the ac tive lesions on serial unenhanced MRI obtained by various pulse sequences h as not been yet considered. We compared the interobserver levels of agreeme nt in reporting active MS lesions on serial enhanced and unenhanced MRT to assess whether the use of various unenhanced techniques may change the degr ee of interobserver measurement reproducibility. Dual-echo conventional spi n echo (CSE), dual-echo fast spin echo (FSE), fast fluid-attenuated inversi on recovery (FLAIR) and Gd-enhanced T1-weighted brain MRI were obtained fro m five MS patients at baseline and monthly for 2 months. Six experienced ob servers independently identified and counted active MS lesions on the two f ollowup MRI scans. Active lesions were considered to be all the enhancing l esions and any new or enlarging lesion on enhanced and unenhanced scans. In terobserver levels of agreement were calculated by weighted kappa values. V ery good agreement was reached only for counting total and new Gd-enhancing lesions. Good agreement was achieved for counting new lesions on the three unenhanced techniques, whereas the agreement for counting enlarging lesion s was poor with all the MRI techniques. The level of agreement was signific antly heterogeneous for Various MRI techniques but not for various lesion s ites. These results confirm that counting enhancing lesions is the most rel iable method for assessing MS activity, but the use of any of the available unenhanced MRI techniques did not result in different levels of interobser ver agreement when reporting new and enlarging MS lesions on serial scans.