Magnetic resonance imaging in primary progressive multiple sclerosis

Ten to fifteen percent of patients with multiple sclerosis (MS) have a condition that is progressive from onset without a preceding relapsing-remitting phase: this is known as primary progressive multiple sclerosis (PPMS). Patients with PPMS tend to be older, often present with motor symptoms and, in contrast to relapsing MS, are as likely to be male as female. The conventional magnetic resonance imaging (MRI) characteristics of PPMS include a tendency to lower lesion loads and lower rate of new lesion formation. In common with relapsing MS, the relation between conventional MRI abnormalities and clinical condition is poor. Studies using newer MRI techniques, such as magnetization transfer imaging (MTI), diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), and functional MRI (fMRI), have also been carried out. These techniques are sensitive to a wider range of abnormalities within tissue, and their increased pathological specificity may be helpful in clarifying the underlying pathology of the condition.