Assessment of demyelination, edema, and gliosis by in vivo determination of T1 and T2 in the brain of patients with acute attack of multiple sclerosis

Abstract

This study intended to investigate the possibility of magnetic resonance (MR) to characterize the acute plaque due to multiple sclerosis (MS). To obtain information, in vivo measurements of relaxation processes were performed in 10 patients with known acute MS plaques, using a whole-body superconductive MR-scanner, operating at 1.5 T. The measurements were repeated several times, from onset of the disease and during remission by use of six-point partial saturation inversion recovery and 32-echo multiple spin-echo sequences, giving T1 and T2, respectively. We also focused on the issue, whether T1 and T2 relaxation processes in fact were monoexponential. The results of the first T1 and T2 measurements of the acute plaques were not clearly different from T1 and T2 of presumably chronic plaques obtained in a group of chronic MS patients previously (H.B.W. Larsson, J. Frederiksen, L. Kjär, O. Hendriksen, and J. Olesen, Magn. Reson. Med. 7, 43 (1988)). In some of the acute plaques a slight initial increase in T1 and T2 was seen, when the measurement was repeated in about 10 days. Thereafter T1 decreased slowly in all but one patient as a function of days. In all cases the T1 relaxation process followed a monoexponential course. The T2 relaxation process was a monoexponential function in the acute plaques, when measured within 20 days from onset of disease. After an average of 78 days, however, the T2 relaxation process clearly became biexponential in all but two patients. Later some of the relaxation curves changed back toward monoexponentiality. Thus, the study shows that it is possible to detect significant changes in MR parameters during the evolution of the disease, and these changes are discussed in relation to knowledge of pathoanatomical events in MS.