This study aims to measure in vivo the spinal cord gray and white matter in patients with Amyotrophic Lateral Sclerosis and healthy persons that match the patients' age and sex using rAMIRA imaging, a novel Magnetic Resonance Imaging (MRI) method. Patients and healthy control persons prospectively undergo MRI examinations, clinical examinations including assessments of disability, and tests of muscle force using hand held dynamometry. Serum markers of neuro-axonal injury are also assessed.

Examinations for patients and healthy control persons are scheduled every six months over a time span of two years.

Inclusion Criteria (patients):

1. 18 years or older
2. neurologist-confirmed possible, probable or definite ALS acc. to El Escorial criteria
3. at baseline: able to lie in an MRI scanner for one hour

Exclusion Criteria (patients):

1. active other neurological or neuromuscular condition explaining the symptoms or a significant part of it
2. other neurological or neuromuscular conditions interfering with the examinations
3. severe cervical spinal stenosis or other relevant disease of the spine or spinal cord that may interfere with study procedures or that may impact the cord segments imaged in this study
4. other severe chronic disease
5. pregnancy
6. general contraindications against MRI scanning (e.g. metal implants, pacemakers)
7. not able to read the patient information due to language barriers (patient information in English and French may be provided)
8. major cognitive deficit impacting the ability to read and understand the patient information and/or to follow the instructions of the study personnel

Inclusion criteria (healthy control persons):

1. 18 years or older
2. able to lie in MRI scanner for one hour

Exclusion criteria (healthy control persons):

1. neurological or neuromuscular conditions
2. other severe chronic disease
3. pregnancy
4. general contraindications against MRI scanning (e.g. metal implants, pacemakers)
5. relevant cervical spinal canal stenosis or other relevant disease of the spine or spinal cord that may interfere with study procedures or that may impact the cord segments imaged in this study
6. not able to read the patient information due to language barriers (patient information in English and French may be provided)

Inclusion criteria (patients with Motor Neuron Diseases other than ALS):

1. 18 years or older
2. neurologist-confirmed Motor Neuron Disease (not ALS)
3. able to lie in MRI scanner for one hour

Exclusion criteria (patients with Motor Neuron Diseases other than ALS):

1. other severe neurologic disease
2. other severe chronic disease
3. pregnancy
4. general contraindications against MRI scanning (e.g. metal implants, pacemakers)
5. relevant cervical spinal canal stenosis or other relevant disease of the spine or spinal cord that may interfere with study procedures or that may impact the cord segments imaged in this study
6. not able to read the patient information due to language barriers (patient information in English and French may be provided)

All patients diagnosed with possible, probable, and definite Amyotrophic Lateral Sclerosis acc. to the El Escorial aged 18 years or older can participate in this study. Healthy control persons are chosen to individually match the included patients. Additionally, patients with other motor neuron diseases (not ALS) will be included.