Clinical Trials

Inclusion Criteria:

1. The patient is determined to have suspected PACNS upon evaluation by a neurologist or rheumatologist or may have an established diagnosis of PACNS of any duration as determined by a neurologist or rheumatologist.
2. Ability to undergo routine clinical testing, including lumbar puncture performed for PACNS to exclude potential alternative diagnoses (for initial suspected cases).
3. Ability to provide informed consent.

Exclusion Criteria:

1. Less than 18 years of age.
2. Any absolute contraindication to 3 Tesla MRI.
3. Any absolute contraindication to gadolinium.
4. Contraindication to lumbar puncture such as severe coagulopathy.
5. High risk carotid atherosclerotic plaque defined as either greater than 70% stenosis or known high risk plaque features such as intra-plaque hemorrhage.
6. Medium or high risk factors for cardioembolic stroke based on the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria.