 The cyclooxygenase COX system is implicated in the pathophysiology of brain diseases, including Alzheimer s disease and depression, and is a potential biomarker for neuroinflammation. COX is the rate-limiting enzyme in the synthesis of prostaglandins from arachidonic acid and exists as two primary isoforms COX-1 and COX-2. Our laboratory recently developed 11CPS13, a novel PET ligand to selectively image COX-1, and initial PET scans in monkey demonstrated that 11CPS13 is a promising ligand. 