A Ra Cho

3′-Deoxy-3′-[18F]fluorothymidine and O-(2-[18F]fluoroethyl)-L-tyrosine PET in Patients with Suspicious Recurrence of Glioma after Multimodal Treatment: Initial Results of a Retrospective Comparative Study

PurposeThe purpose of this study was to compare the uptakes and diagnostic accuracies between 3′-deoxy-3′-[18F]fluorothymidine (FLT) and O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET in patients with a clinical suspicion of having a recurrence of glioma after multimodality treatment.MethodsThirty-two patients who underwent FLT and FET PET due to abnormal enhancement on magnetic resonance (MR) images were included. According to surgical confirmation or follow-up results, patients were divided into those with therapy-related benign changes (TRBCs) and those with recurrence. Recurrences were divided again into initial low-grade glioma (LGG) and high-grade glioma (HGG). The uptakes of FLT and FET were compared with the maximum standardized uptake value (SUVmax) and lesion-to-normal ratio (LNR). The diagnostic accuracies were compared via a receiver-operating-characteristic (ROC) curve analysis.ResultsThe LNRs of FLT in recurrences with initial HGG (8.26 ± 5.02) were significantly higher than those in recurrences with initial LGG (3.43 ± 2.14) and TRBC (1.81 ± 0.60). The LNRs of FET in recurrence with initial HGG (2.70 ± 0.48) and LGG (3.03 ± 1.32) were significantly higher than those in the TRBC (1.60 ± 0.47). The areas under the ROC curve (AUCs) of FLT and FET for initial LGG were 0.768 and 0.893, respectively. The AUCs of FLT and FET for initial HGG were 1.000 and 0.964. However, there were no statistical significances. The results for comparing with SUVmax were the same as those with LNR.ConclusionsUptakes of FLT were different according to initial grade in patients with recurrent glioma, but those of FET were not. However, there were no statistical significances in the diagnostic accuracies according to initial grade between the two tracers in this study.

The Prevalence and Characteristics of Brown Adipose Tissue in an 18 F-FDG PET Study of Koreans

PurposeThe object of this study was to evaluate the prevalence and characteristics of brown adipose tissue (BAT) in Korean subjects using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET).MethodsSix thousand and five consecutive 18F-FDG PET/CT scans of 5,115 patients (3,007 females and 2,108 males, mean age 53.5 years) were retrospectively reviewed. We characterized the nature of BAT, such as its location, and we assessed the influence of sex, age, body mass index (BMI), and temperature on BAT.ResultsThe prevalence of BAT in Koreans in a single 18F-FDG PET/CT scan in average conditions was 1.07%. The BAT detection rate was higher in females than males (1.32% vs 0.73%), and also with younger age (7.94% vs 0.73%), lower BMI (BMI with BAT, 21.1 vs BMI without BAT, 23.15) and cold outdoor temperature (1.65% vs 0.49%). The most frequent location of BAT was the supraclavicular area (left, 0.91%; right, 0.88%) and ventral neck area (left, 0.62%; right, 0.63%).ConclusionsThe characteristics of BAT in Koreans are not different from those described for Caucasians. However, the low prevalence of BAT in our study might be related to some scan condition like ambient temperature, but further study is needed.