A follow-up study of very low field MRI findings and clinical course in multiple sclerosis

Seventy-three consecutive patients with definite multiple sclerosis (MS) were examined with very low field (0.17 and 0.02 tesla) magnetic resonance imaging (MRI) of the brain. Fifty-seven patients were examined a second time after 6 months, 41 patients a third time after 1 year, and 25 patients a fourth time after 2 years. The initial finding was abnormal in 57/73 patients (78%). The number of lesions increased with age, duration of disease, and increasing disability. Plaques were more numerous in progressive than in remitting MS. Of the patients with abnormal MRI 65% had more than 3 lesions, and in 82% lesions were smaller than 2.5 cm in diameter. After follow-ups of 1 year and 2 years the size of MRI lesions remained unchanged in 55% and 64%, respectively. Unchanged plaque numbers were found in 72% and 60%. Unchanged MRI was most common among patients with remitting MS who were in a stable phase. Decrease in size and disappearance of plaques correlated well with clinical remissions. Increase in size was rare even during relapses. New plaques could appear during all phases of clinical course although they reflected better a relapse of remitting or progressive disease.