Assessing PET Parameters in Oncologic 18F-FDG Studies

PET imaging, particularly oncologic applications of 18F-FDG, has become a routine diagnostic study. To better describe malignancies, various PET parameters are used. In 18F-FDG PET studies, SUVmax is the most commonly used parameter to measure the metabolic activity of the tumor. In obese patients, SUV corrected by lean body mass (SUL), and in pediatric patients, SUV corrected by body surface area, are recommended. Metabolic tumor volume is an important parameter to determine the local and total tumor burden. Total lesion glycolysis (SUVmean × metabolic tumor volume) provides information about averages. Some treatment response assessment protocols recommend using the SUVpeak or SULpeak of the tumor. Tumor-to-liver ratio and tumor–to–blood-pool ratio are helpful when comparing studies for treatment response assessment. Dual–time-point PET imaging with retention index can help differentiate malignant from benign lesions and may help detect small lesions. Dynamic 18F-FDG PET imaging and quantitative analysis can measure the metabolic, phosphorylation, and dephosphorylation rates of lesions but are mainly used for research purposes. In this article, we will review the currently available PET parameters in 18F-FDG studies with their importance, uses, limitations, and reasons for erroneous results.