Avid Radiopharmaceuticals is an American company, founded by Dr. Daniel Skovronsky, and based at the University City Science Center research campus in Philadelphia, Pennsylvania. The company has developed a radioactive tracer called florbetapir (18F). Florbetapir can be used to detect beta amyloid plaques in patients with memory problems using positron emission tomography (PET) scans, making the company the first to bring to market an FDA-approved method that can directly detect this hallmark pathology of Alzheimers disease. Venture investors include Alta Partners, Osage University Partners, and Safeguard Scientifics. Eli Lilly and Company announced on November 8, 2010, that they would acquire Avid for $800 million, with $300 million paid out up front and the balance paid later on. Since the disease was first described by Dr. Alois Alzheimer in 1906, the only certain way to determine if a person indeed had the disease was to perform an autopsy on the patients brain to find distinctive spots on the brain that show the buildup of amyloid plaque. Doctors must diagnose the disease in patients with memory loss and dementia based on symptoms, and as many as 20% of patients diagnosed with the disease are found after examination of the brain following death to not have had the condition. Other diagnostic tools, such as analysis of cerebrospinal fluid, magnetic resonance imaging scans looking for brain shrinkage and PET scans looking at how glucose was used in the brain, had all been unreliable.