Interscanner variation in brain MR lesion load measurements in multiple sclerosis using conventional spin-echo, rapid relaxation-enhanced, and fast-FLAIR sequences

BACKGROUND AND PURPOSE: Different MR pulse sequences have been proposed for measuring multiple sclerosis (MS)-related abnormalities, The reproducibili ty of measured brain MS lesion volumes was compared for MR images performed using different scanners and different pulse sequences. METHODS: Nine patients with relapsing-remitting MS were each imaged on two scanners and, on each occasion, dual-echo conventional spin-echo, dual-echo rapid-acquisition relaxation-enhanced (RARE), and fast fluid-attenuated in version recovery (fast-FLAIR) images were obtained. The lesion volume prese nt on each image was evaluated three times by a single observer in random o rder, using a local thresholding technique. RESULTS: The mean lesion volumes present on fast-FLAIR images were signific antly higher than those measured on dual-echo conventional spin-echo and RA RE images. The mean intraobserver coefficients of variation for the differe nt sequences and scanners ranged from 3.0% to 4.2% (no statistically signif icant difference), For each of the sequences, the use of different scanners introduced a variability that was higher than the intraobserver variabilit y: the interscanner coefficient of variation was 7.4% for conventional spin -echo, 9.5% for RARE, and 18.5% for fast-FLAIR images. CONCLUSION: Our study confirms that the use of different scanners significa ntly influences lesion loads measured from MR images of patients with MS an d establishes that newer sequences are more susceptible to measurement vari ability. It also indicates that, if newer sequences are to be used in clini cal trials, careful standardization is needed.