Inclusion Criteria:  Consent form signed by the patient Patients suspected ALS defined according Awaji Shima criteria (possible, probable, defined) Clinical assessment of upper motor neuron involvement Electrophysiologic assessment of lower motor neuron involvement  Exclusion Criteria:  inability to give informed consent a contraindication to MRI respiratory failure impairing ability to lie flat in the scanner. Patient placed under judicial protection or under another protective regime, Females who are pregnant