Signal intensity on MRI of basal ganglia in multiple sclerosis.

It has been reported that a relative reduction in signal intensity on T2 weighted MRI may be seen in the basal ganglia of patients with multiple sclerosis and furthermore that this is due to excessive iron deposition. The basal ganglia are, however, rarely involved clinically or pathologically in multiple sclerosis, casting some doubt on this finding. Therefore MRI was carried out in 46 patients with definite multiple sclerosis and 42 age matched controls. Contiguous, 5 mm thick axial dual echo spin-echo images of the brain were obtained on a 1.5T imager. Visual rating scales were used to measure the lesion load as well as the signal intensity of the globus pallidus, putamen, caudate nucleus, substantia nigra, red nucleus, and thalamus. There was a mild degree of low signal intensity in the patient group in the thalamus only. The signal intensity of the thalamus and putamen was never lower than that of the globus pallidus. Low signal in the basal ganglia is rarely, if ever, found in multiple sclerosis and is not a useful radiological sign.