The role of PET quantification in neurological imaging: FDG and amyloid imaging in dementia

Positron emission tomography (PET) with FDG or amyloid tracers is an important diagnostic tool, which also provides imaging biomarkers for patient selection in therapeutic trials in Alzheimer's disease. PET is also a quantitative technique with the potential to measure disease severity and progression. Limitations in spatial resolution result in partial volume effects that can be minimized by correction algorithms and image reconstruction with resolution recovery. Quantitative local rates of cerebral glucose metabolism can be calculated from FDG uptake. Reaching the highest degree of accuracy still requires blood sampling, while bloodless techniques have improved and can provide useful approximations. Advanced image processing techniques allow semiautomatic standardised assessment of diagnostic metabolic patterns and disease severity. Amyloid imaging provides excellent categorical classification of fibrillary amyloid deposition, but quantitative measures derived from amyloid tracer uptake are less well understood.