Abstract
Positron emission tomography (PET) imaging, particularly oncologic applications of fluorine-18 fluorodeoxyglucose (18F-FDG), has become a routine diagnostic study. To better describe the malignancies, various PET parameters are used. In 18F-FDG PET studies, maximum standardized uptake value (SUVmax) is the most commonly used parameter to provide a measurement of the metabolic activity of the tumor. In obese patients, SUV corrected by lean body mass (LBM) (SUL or SUVSUL) and in pediatric cases, SUV corrected by body surface area are recommended. Metabolically active tumor volume (MTV) is an important parameter to determine the local and total tumor burden. Total lesion glycolysis (TLG) (SUVmean x MTV) provides information about average total tumor glycolysis. Some treatment response assessment protocols recommend using peak SUV (SUVpeak) or peak SUL (SULpeak) of the tumor. Tumor to liver ratio (TLR) and tumor to blood pool ratio (SUR) is helpful when comparing studies for treatment response assessment. Dual-time point PET imaging with retention index (RI) can help differentiating malignant from benign lesions and may help detecting small lesions. Dynamic 18F-FDG PET imaging (dPET) and quantitative analysis can measure the metabolic, phosphorylation and de-phosphorylation rates of the lesions but they are mainly used for research purpose. In this article we will review the currently available PET parameters in 18F-FDG studies with their importance, usage, limitations, and reasons causing erroneous results.