What primary factor influences SUV measurements in PET imaging?

The primary factor that influences Standardized Uptake Values (SUV) measurements in PET imaging is the injected dose of the radiopharmaceutical. SUV is a quantitative measurement that assesses the concentration of radioactivity in a region of interest relative to the patient's body weight or body surface area. Since SUV is calculated using the activity concentration (which is directly affected by the dose that is administered), variations in the injected dose can lead to differences in SUV values.

If a larger dose is injected, the radioactivity concentration will be higher, often resulting in a higher SUV measurement. Conversely, a smaller injected dose will typically yield a lower SUV value. Therefore, the accuracy and reliability of SUV as a measure of tissue metabolism or tumor activity depend significantly on the consistency and appropriateness of the injected dose used in the imaging procedure. Other factors, while they may influence SUV values as well, do not play as critical a role as the injected dose in establishing the baseline for these measurements.