Warming patients by changing the ambient environment (rather than core temperature) has been reported to reduce brown adipose tissue activity, thereby reducing artifacts in 18 F-FDG PET. Nonetheless, a reduction in cardiac uptake of 18 F-FDG has been incidentally noted during ambient warming. This study examined the impact of seasonal variations in ambient temperatures on cardiac uptake of 18 F-FDG. Methods: Consecutive 18 F-FDG PET patients were recruited into summer and winter cohorts. The protocol was highly standardized; however, data were excluded when scanning took place other than 60 min after injection. Mean and maximum counts per pixel in the cardiac region and cardiac standardized uptake value were determined and correlated with the daily minimum, maximum, and mean temperature (day of scan), mean temperature on the scan day and preceding 2 d (3-d window), and mean temperature 1, 2, 3, and 4 wk before scanning. Results: No statistically significant differences were noted between cohorts (summer and winter) for age, sex, weight, height, or dose. As expected, the summer cohort was associated with statistically higher minimum, maximum, and mean temperatures, longer days, and greater sunlight hours (all P , 0.001). The mean and maximum heart counts were statistically higher in winter than summer (P 5 0.031 and P 5 0.024, respectively). The cardiac standardized uptake value was statistically higher for winter than summer (P 5 0.026). The key factors in cardiac accumulation of 18 F-FDG were the minimum temperature on the day of the scan and the 3-d mean temperature. Conclusion: Cardiac accumulation of 18 F-FDG is influenced by the ambient temperature, in particular the minimum temperature on the day of the scan and the 3-d average temperature before the scan. Further investigation is warranted to examine the impact of this observation on clinical protocols and cardiac 18 F-FDG PET study results. PET with the glucose analog tracer 18 F-FDG evaluates cellular metabolism and is commonly used for the detection and staging of disease in oncology patients (1-3). 18 F-FDG PET is also widely used to assess myocardial viability (4,5). 18 F-FDG PET in oncology has been reported to confront issues with artifactual accumulation of 18 F-FDG in brown adipose tissue (BAT) (6). Warming patients by changing the ambient environment (rather than core temperature) has been reported to successfully reduce BAT activity; however, one recent report noted that warming patients also reduced cardiac uptake of 18 F-FDG (Fig. 1) (6). Although this observation may relate to seasonal variations in cardiac event rates, there may also be important implications for cardiac 18 F-FDG PET diagnostic integrity. Cardiac glucose metabolism depends on numerous factors including substrate availability, cardiac workload, myocardial perfusion, and medication (7). Increased sympathetic activity drives increased metabolic demand for glucose (8,9), and although the connection has yet to be reported in the literature, this investigation hypothesized that t...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.