Disease activity in multiple sclerosis studied by weekly triple-dose magnetic resonance imaging

This study assessed whether dysfunction of the blood-brain barrier is an ob ligatory early event in lesion formation in multiple sclerosis. Dual-echo a nd T1-weighted magnetic resonance imaging after the injection of a triple d ose (0.3 mmol/kg) of gadolinium-DTPA were obtained from ten patients with r elapsing-remitting multiple sclerosis every week for 2 months. Sixty-four n ewly active lesions were detected by the two techniques. All the 44 new les ions seen on dual-echo scans enhanced during the early phases of their form ation: 33 at their first appearance, 10 1 week before their appearance on t he dual-echo scans, and one the week thereafter. When the every fourth (mon thly) scan was analyzed, a total of 55 newly active lesions were detected ( i.e., 14% active lesions would have been missed compared to the number foun d on weekly scanning). Thirty-one of them were detected by both dual-echo a nd triple-dose scans, 15 only by enhanced scans, and nine only by dual-echo scans. This study confirms that with highly sensitive magnetic resonance i maging techniques dysfunction of the blood-brain barrier is an obligatory e arly event in new lesion formation in relapsing-remitting multiple sclerosi s.