Pittsburgh compound B (PiB) is a radioactive analog of thioflavin T, which can be used in positron emission tomography scans to image beta-amyloid plaques in neuronal tissue. Due to this property, Pittsburgh compound B may be used in investigational studies of Alzheimer's disease. The definitive diagnosis of Alzheimer's disease can only be made following the demonstration of the presence of beta-amyloid (Aβ) plaques and neurofibrillary tangles, the pathologic hallmarks of Alzheimer's disease in brain tissue, typically at autopsy. While the cognitive impairments of the disease could be monitored throughout the disease course, clinicians had no reliable way to monitor the pathologic progression of the disease. Due to this fact, a clear understanding of the process of amyloid deposition and how amyloid deposits relate to the cognitive symptoms of Alzheimer's disease remains to be elucidated. While sophisticated centers for the treatment of Alzheimer's disease are able to diagnose the disease with some reliability based on its clinical presentation, the differential diagnosis of Alzheimer's disease from other dementias is less robust. Furthermore, as novel disease-modifying therapies for Alzheimer's disease that attack and remove beta-amyloid deposits from the brain enter clinical trials, a pre-mortem tool for assessing their effectiveness at clearing the amyloid deposits was a much needed development. To answer these needs, a research team from the University of Pittsburgh led by geriatrics psychiatrist William E. Klunk and radiochemist Chester A. Mathis synthesised charge-neutral benzothiazoles derived from thioflavin T, which included a small number of compounds with suitable properties for use as a positron emission tomography imaging agent. One of these compounds, 2-(4'-[11C]methylaminophenyl)-6-hydroxybenzothiazole, was tested in human subjects. The University of Pittsburgh team partnered with a team of researchers from Uppsala University in Uppsala, Sweden, to conduct the first trials of this new agent in human research subjects.