Magnetic resonance imaging was used to evaluate the cerebral white matter of three subject groups: ( I ) 22 patients with known multiple sclerosis (MS) (1 1 with disease of shorter duration (0-5 years) and 11 with disease of longer duration (>5 years)); (2) 9 patients with suspected MS; and (3) 12 normal volunteers. Transverse spin-echo (SE) 30/ 500 and 120/ 1000 radiofrequency pulse sequences were used for anatomic localization and plaque identification, respectively, while combined spin echo-inversion recovery was used for TI determination. TI values were calculated for grossly normal cerebral white matter in the frontal, parietal, and occipital lobes of normal volunteers and MS patients, and for plaques in MS patients. When compared with normals, the T I values of plaquefree areas from definite MS patients (shorter and longer duration disease groups combined) were significantly longer in the frontal lobe (MS = 374 f 34 ms, Normal = 352 +-39 ms, P < 0.05) and in the occipital lobe (MS = 414 f 37, Normal = 378 * 40, P < 0.02).
Although the TI values of the shorter duration MS group were longer than those of normals, the difference was not statistically significant. Thus, the significant difference between the definite MS group (both shorter and longer duration) is more heavily weighted by the longer duration MS group. Ti values in patients with suspected MS without plaques were not significantly different from those of normals. In diagnosed MS patients, T, values of plaques were significantly longer than TI values of corresponding normal areas ( P < 0.05).
In conclusion, plaque-free white matter in patients with clinically diagnosed MS has longer TI values than white matter in normals, suggesting the presence of biophysical abnormalities which are not seen on other routine imaging modalities. These differences may be accentuated as the disease progresses. Thus, it may be possible in the future to evaluate MS disease activity based on TI characteristics of normal appearing white matter. o 1986 Academic Press, Inc.