Lesion load quantification on fast-flair, rapid acquisition relaxation-enhanced, and gradient spin echo brain MRI scans from multiple sclerosis patients

Previous studies have addressed the issue of the usefullness of fast fluid- attenuated (fast-FLAIR), rapid acquisition relaxation-enhanced (RARE), and gradient spin echo (GRASE) sequences in small groups of patients with multi ple sclerosis (MS). The aim of this study was to assess and compare the les ion volumes and the intra-rater reproducibility of such measurements using fast-FLAIR, dual echo RARE, and dual echo GRASE brain scans from a large sa mple of MS patients. Using a 1.5 Tesla scanner, fast-FLAIR, dual echo RARE, and dual echo GRASE scans (24 axial, 5-mm thick contiguous interleaved sli ces) of the brain were obtained from 50 MS patients. Total lesion loads (TL L) were assessed twice using a semi-automated local thresholding segmentati on technique by the same rater from the scans obtained with the three techn iques. Mean TLL were 20.3 mt for fast-FLAIR, 16.6 mt for RARE, and 17.6 mt for GRASE sequences. Mean TLL detected by the three techniques were signifi cantly heterogeneous (p < 0.001); at post-hoc analysis, the mean lesion vol ume detected on fast-FLAIR images was significantly higher than that on bot h RARE and GRASE images (p < 0.001) and the mean TLL on GRASE scans was sig nificantly higher than that on RARE scans (p = 0.001). The mean values of i ntra-observer coefficient of variation for TLL measurements were: similar f or the three techniques (2.69% for fast-FLAIR, 2.33% for RARE, and 2.65% fo r GRASE). Our results confirm that fast-FLAIR sequences detect higher lesio n volumes than those detected by other magnetic resonance imaging (MRI) seq uences with shorter acquisition times. However, the reproducibility of TLL measurements is comparable among fast-FLAIR, RARE, and GRASE. This suggests that when assessing MS disease burden with MRI, the choice of the pulse se quence to be used should be dictated by the clinical setting. (C) 1999 Else vier Science Inc.