Standardized phantoms exist for X-ray machines, CT scanners, and other imaging modalities to calibrate devices regularly. X-ray phantoms, for example, absorb X-rays in predictable ways, consisting of materials that mimic how the human body attenuates such electromagnetic radiation. But, making a calibration phantom for positron emission tomography (PET) scanners is very different from other phantoms because it has to replicate how radioactive tracers look like after being injected into a patient. Germanium is loaded into a special vessel and a PET scanner is used to observe the changing radioactive glow from day to day, providing a value against which to adjust the scanner. These exist, but there is no standard phantom that can be used in PET scanners from different manufacturers. Read more.

In two cases of progressing dementia, PET imaging with amyloid and tau tracers helped to clarify the diagnosis by ruling out Alzheimer's disease, researchers suggested.

Case 1 was a 71-year-old former NFL player who had experienced numerous concussions during his career and was developing what appeared clinically to be Alzheimer's disease. However, PET scanning with the [¹⁸F]-florbetapir tracer showed no evidence of cerebral amyloid plaques, which excluded Alzheimer's, according to Samuel Gandy, MD, of the Icahn School of Medicine at Mount Sinai in New York, and colleagues.

Case 2 was a 59-year-old physician who had suffered a head injury skiing, but who also had shown personality, mood, and cognitive changes in the months before the injury. Amyloid imaging with [¹⁸F]-florbetapir PET was negative except for at the site of the head injury, and the diagnosis of Alzheimer's disease (AD) was therefore ruled out, the researchers reported online in Translational Psychiatry. Read more.