Table 2.

Most relevant factors impacting the SUV.

Patient-related	Instrumentation-related	Operator-related
Not controllable • Patient size • Postural flexibility of the patient for the various treatment positions. • Capacity of patient to remain immobile in a given position. • Patient movement and breathing. • Levels of blood glucose and insulin. • Non-uniform uptake within the tumour (necrotic centre) • Diffusion in the tissue. Controllable • Radiopharmaceutical • Isotope emission β+ • Dose administered. • Residual activity in the needle. • Uptake time before acquisition of images • Acquisition time	• Partial volume effect • Discrimination in scatter events • Sensitivity • Mode of acquisition (2D vs. 3D) • Method used to correct attenuation (CT vs. Germanium sources) • Truncation • Movement (different time scales, CT vs. PET) • Acquisition with respiratory control (4D) • Availability of corrections for movement • Artefacts due to CT movement • Use of contrast agents • Subtraction of the background • Reconstruction Algorithm: (Filtered Back Projection vs. OSEM) • Reconstruction by time of flight • Incorrect synchronization of watches	• Quality of injection administration • Acquisition and reconstruction protocols • Image acquisition time • Image interpretation • Difficulty determining the SUV threshold • Analytical tools not designed to measure a change in SUV • Interobserver variability • Determination of ROI