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 Alzheimer's disease. 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. Detection of Alzheimer's disease Since the disease was first described by Alois Alzheimer in 1906, the only certain way to determine if a person indeed had the disease was to perform an autopsy on the patient's 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. Avid built on research done by William Klunk and Chester Mathis who had developed a substance called Pittsburgh compound B as a means of detecting amyloid plaque, after analyzing 400 prospective compounds and developing 300 variations of the substance that they had discovered might work. In 2002, a study performed in Sweden on Alzheimer's patients was able to detect the plaque in PET brain scans. Later studies on a control group member without the disease did not find plaque, confirming the reliability of the compound in diagnosis. While the tool worked, Pittsburgh compound B relies on the use of carbon-11, a radioactive isotope with a half-life of 20 minutes that requires the immediate use of the material prepared in a cyclotron. Dr. Skovronsky established Avid Radiopharmaceuticals in July 2005 with the goal of finding a dye that could be injected into the body, would cross the blood–brain barrier and attach itself to amyloid protein deposits in the brain. The firm raised $500,000 from BioAdvance, the Biotechnology Greenhouse of Southeastern