Validity of a simple spillover correction for positron emission tomography measurements in the cerebrospinal fluid region

Positron emission tomography (PET) measurements in the cerebrospinal fluid (CSF) region may be overestimated because of spillover artifacts from surrounding radioactivity. In this study, we proposed a simple spillover correction method (subtraction method) and evaluated its validity. A cylindrical phantom simulating brain ventricles was used to compare the subtraction method with the geometric transfer matrix (GTM) correction approach. And the subtraction method was applied to dynamic PET images of [¹⁸F]fluorodeoxyglucose (FDG), [¹⁸F]fluorodopa (FDOPA), and [¹¹C]raclopride (RAC), and [¹⁵O]H₂O (H₂O). The effects of spillover correction on CSF measurements were assessed. Both methods effectively reduced spillover artifacts in the phantom study. In dynamic PET images, after spillover correction, time-activity curves for FDG, FDOPA, and RAC approached near-zero levels in the CSF, whereas H₂O continued to show increasing activity over time. This approach effectively reduces artifacts and offers the advantages of simpler volume-of-interest settings and straightforward calculation procedures.