A translator gets distracted by every rustle in the room, and an hour-long meeting stretches into two, while the meaning still gets garbled. The same happens with PET scanning of the brain: the radioactive tracer that highlights amyloid plaques washes out of tissues over time, and the standard method of assessment begins to overestimate their number. Amyloid plaques are clumps of protein that appear in the brain in Alzheimer's disease.
Scientists have found a way to remove this noise. They noticed that the washout rate of the tracer differs across brain regions and built simple models that predict this rate from the level of accumulation. Then they applied the correction to data from 88 older adults. The result: the error decreased by a factor of 2-5, and a short scan (just 15 minutes) began to give almost the same accurate result as a long hour-long study.
This method can be used right away in clinics to diagnose Alzheimer's disease faster and more accurately and to monitor changes during treatment.
Pittsburgh Compound B ([11C]PiB) is named after the University of Pittsburgh, where it was developed, and is a derivative of the dye thioflavin-T, which binds to amyloid fibrils. The half-life of carbon-11 is only 20 minutes, so scanning must begin right after injection, and a short 30–45 minute protocol fits within a single patient visit.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.