Positron emission tomography (PET) has been widely used in early diagnosis of tumors. Though standardized uptake value (SUV) is a common diagnosis index for PET, it will be affected by the size of the tumor. To explore how the tumor size affects imaging diagnosis index, dynamic PET images were simulated to study the relationship between tumor size and the imaging diagnosis index. It was found that the SUV of the region of the tumor varied with scan time, and the SUV was always lower than the true value of tumor. Even more deviations were found in SUV with a reduced tumor size. The diagnosis index SUV(max) was more reliable than SUV, for it declined only when the volume of tumor was less than 3 mm(3). Therefore, the effect of tumor size on the SUV and SUV(max) that are used as diagnosis indices in the early diagnosis of tumors should not be neglected.
Keywords: Standardized uptake value; diagnosis; maximum standardized uptake value; positron emission tomography; tumor size.