Abstract
Objectives: Gadolinium (Gd) is toxic and to avoid its deposition in the tissues, it must be chemically bonded with nonmetal ions to facilitate its excretion by the kidneys. High signal intensity in the dentate nucleus (DN) and globus pallidus (GP) on unenhanced T1-weighted MR images has been both morphologically and pathologically linked to gadolinium-based contrast agent (GBCA) retention in the brain. The purpose of this study is to determine if repeated administrations of GBCA would affect the uptake of 18F-FDG in the DN and GP on PET/CT. Methods: 376 patients who had both contrast enhanced MR (CE MR) of the brain and PET/CT from Jan 2004-Oct 2015 were identified. Patients with a history of brain irradiation, hepatic or renal disease were excluded. The maximum standardized uptake value (SUVmax) was measured in the DN and GP on the PET/CT in patients who had 3 to 6 successive CE MR brain studies. The SUVmax of the corresponding areas in the control group of patients who had no prior CE MR, and a normal, unenhanced MR of the brain was also measured. A Wilcoxon two-sample test was used for statistical analysis. Results: 15/376 (4%) cases [mean age 54±18, M:F = 10:5] were included in the subject group, and 15 cases [mean age 36±9, M:F = 11:4] were included in the control group. The median DN SUVmax was significantly lower in the subject group than in the control group (5.4 vs. 6.4, respectively; P = 0.021). Similarly, the median GP SUVmax was significantly lower in the subject group than in the control group (8.8 vs. 12.1, respectively; P = 0.003). Conclusion: The median SUVmax in the DN and GP were 16% and 27% lower respectively in patients who received GBCAs compared to those who had not received GBCAs. This could be related to Gd deposition in these areas.