In your mind, does the word "centiloid" conjure up images of a small creature with too many legs? Instead, think centimeter yardstick, or thermometer. A centiloid is a proposed unit of measure on a unified scale for all amyloid-beta imaging tracers used in positron emission tomography (PET). Alzheimer's disease scientists use a handful of ligands in research already, and while the FDA thus far has approved only one - Amyvid - for clinical use, other approvals appear likely. Since each tracer has its own chracteristic signal strength, comparing them remains difficult. Enter, the Centiloid Project. William Klunk, University of Pittsburgh, Pennyslvania, presented the idea at the 7th Human Amyloid Imaging meeting held 16-18 January in Miami, Florida.
The problem is that scientists cannot easily compare the results from different tracers. For example, it is known that PiB generates a stronger signal than Amyvid, but side-by-side comparisons are rare. Most studies and clinics use either one or the other, and scientists cannot easily interpret a scan taken with one tracer relative to one taken with another.
"This [project] could really help give us a numerical scale we can all understand - like everyone having a common language," said William Jagust, University of California, Berkeley, a member of the Centiloid Project working group.
Klunk laid out a plan for deriving this standard unit.