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Signal intensity on MRI of basal ganglia in multiple sclerosis
J Grimaud1, J Millar, J W Thorpe
1NMR Research Unit, Institute of Neurology, London, UK.
Abstract:
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.
Insights
Previous studies suggested reduced T2 signal in the basal ganglia of multiple sclerosis patients due to iron. This study found no significant basal ganglia signal reduction in multiple sclerosis, indicating it
Area of Science:
- Neuroimaging
- Neurology
- Radiology
Background:
- Previous research indicated reduced T2-weighted magnetic resonance imaging (MRI) signal intensity in the basal ganglia of multiple sclerosis (MS) patients, attributed to iron deposition.
- Clinical and pathological evidence suggests rare involvement of the basal ganglia in MS, questioning the validity of MRI findings.
Purpose of the Study:
- To investigate the presence and significance of basal ganglia signal intensity changes on MRI in patients with definite multiple sclerosis.
- To determine if reduced signal intensity in the basal ganglia is a reliable radiological marker for multiple sclerosis.
Main Methods:
- MRI scans (5 mm thick axial dual echo spin-echo images) were performed on 46 patients with definite MS and 42 age-matched healthy controls using a 1.5T imager.
- Visual rating scales assessed lesion load and signal intensity in specific basal ganglia structures (globus pallidus, putamen, caudate nucleus, substantia nigra, red nucleus) and the thalamus.
Main Results:
- A mild degree of low signal intensity was observed exclusively in the thalamus of the multiple sclerosis patient group.
- Signal intensity in the thalamus and putamen was consistently not lower than that of the globus pallidus across all participants.
- No significant reduction in basal ganglia signal intensity was detected in multiple sclerosis patients compared to controls.
Conclusions:
- Reduced signal intensity in the basal ganglia is rarely observed in multiple sclerosis.
- The finding of low signal in the basal ganglia is not a useful radiological sign for diagnosing or characterizing multiple sclerosis.
- This study casts doubt on the association between basal ganglia iron deposition and multiple sclerosis.