An international group of experts in pharmacokinetic modeling recommends a consensus nomenclature to describe in vivo molecular imaging of reversibly binding radioligands.

The aim of this guideline is to provide a minimum standard for the acquisition and interpretation of PET and PET/CT scans with [18F]-fluorodeoxyglucose (FDG). This guideline will therefore address general information about [18F]-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) and is provided to help the physician and physicist to assist to carrying out, interpret, and document quantitative FDG PET/CT examinations, but will concentrate on the optimisation of diagnostic quality and quantitative information.

Regional cerebral blood flow (CBF), oxygen extraction ratio (OER), oxygen utilization (CMRO₂) and blood volume (CBV) were measured in a group of 34 healthy volunteers (age range 22–82 yrs) using the ¹⁵O steady-state inhalation method and positron emission tomography. Between subjects CBF correlated positively with CMRO₂, although the interindividual variability of the measured values was large. OER was not dependent on CMRO₂, but highly negatively correlated with CBF. CBV correlated positively with CBF. When considering the values of all the regions of interest within a single subject, a strict coupling between CMRO₂ and CBF, and between CBF and CBV was found, while OER was constant and independent of CBF and CMRO₂. In ‘pure’ grey and white matter regions CMRO₂, CBF and CBV decreased with age approximately 0.50% per year. In other regions the decline was less evident, most likely due to partial volume effects. OER did not change or showed a slight increase with age (maximum in the grey matter region 0.35%/yr). The results suggest diminished neuronal firing or decreased dendritic synaptic density with age.