DETECTING NEW LESION FORMATION IN MULTIPLE-SCLEROSIS - THE RELATIVE CONTRIBUTIONS OF MONTHLY DUAL-ECHO AND T-1-WEIGHTED SCANS AFTER TRIPLE-DOSE GADOLINIUM

In this study, we evaluated the frequency of formation of new lesions on brain magnetic resonance imaging (MRI) from patients with relapsing -remitting multiple sclerosis (MS) and defined the relative contributi ons of unenhanced and enhanced MRI. Every 4 weeks for 3 months, dual-e cho and postcontrast T-1-weighted (5 min after the injection of 0.3 mm ol/kg gadolinium-DTPA) scans were obtained from 28 patients with relap sing-remitting MS. New lesions were defined as those present on dual-e cho and/or postcontrast T-1-weighted scans but with no corresponding M RI abnormalities on any of the preceding scans. A total of Ill newly f ormed lesions were detected during the follow-up on dual-echo and post contrast T-1-weighted scans (i.e., an average of 1.3 lesions per patie nt per month). Ninety-eight (88%) of such lesions were seen on both du al-echo and postcontrast T-1-weighted scans, whilst 13 (12%) were seen only with one of the two techniques: 9 only on dual-echo and 4 only o n postcontrast scans. Five of the 98 new lesions seen by both techniqu es were seen by postcontrast scans 1 month before their appearance on dual-echo scans. Our study suggests that both dual-echo and postcontra st T-1-weighted scans are useful to detect newly formed lesions in pat ients with MS. This is of importance when using MRI to monitor the eff icacy of treatments which may halt MS lesion formation.