DIFFERENTIAL-DIAGNOSIS OF MULTIPLE-SCLEROSIS - CONTRIBUTION OF MAGNETIC-RESONANCE TECHNIQUES

It is widely accepted that magnetic resonance imaging (MRI) findings a re not totally specific for the diagnosis of multiple sclerosis. White matter lesions that mimic those of multiple sclerosis may be detected in both normal volunteers and patients harbouring different diseases. Virtually all the characteristic features of multiple sclerosis are s ometimes encountered in other conditions affecting predominantly the w hite matter. Different conditions such as vasculitis, subcortical athe rosclerotic leukoencephalopathy, Lyme disease, or acute disseminated e ncephalomyelitis can be virtually indistinguishable from multiple scle rosis on conventional MR images. Also the FLAIR technique adds little to the differential diagnosis. The calculation of magnetisation transf er ratio (MT ratio) may be useful to better characterise some entities , such as vasculitis, from multiple sclerosis.