what is suv in pet scan

The standard uptake value (SUV) is a measure of the tracer uptake in a region of interest that normalizes the lesion activity to the injected dose of radioactivity per kilogram of the patients body weight. It is a mathematically derived ratio of tissue radioactivity concentration at a point in time and is used to measure response of cancers to treatment. SUV is considered a semi-quantitative value as it is vulnerable to other sources of variabilities. The most reliable method of measuring activity levels would be to use fractional uptake rate (FUR) which is measured from blood samples. As the FUR and SUV are proportional, careful usage of SUV is widely used over blood sampling. However, SUV may be influenced by image noise, low image resolution, and variable user-biased region of interest (ROI) selection. The cut off between benign and malignant lesion/nodule is in the SUV range of 2.0-2.5. It is important to note that many infectious and inflammatory processes will also have high SUV.