The comparison of three different molecular imaging methods in localization and grading of insulinoma
Lina Chang, Xinyu Bi, Shuo Li, Qi Tong, Yian Gu, Zonghao He, Yansheng Li, Qiusong Chen, Jingqiu Cui, Haonan Yu, Qing He, Ming Liu
Abstract
Aims This cross-sectional study compared the value of molecular imaging (Exendin-4 positron emission tomography/computed tomography [PET/CT], 68 Ga-DOTATATE PET/CT, 18 F- fluorodeoxyglucose [FDG] PET/CT) in insulinoma localization by stratified tumor size and grading, and explored the correlation of the related the maximum standardized uptake value (SUVmax) with insulinoma grading, Ki-67, maximum tumor diameter, and glucose metabolism. Methods In 28 insulinoma patients, the sensitivity of three types of PET/CT for localizing insulinoma was calculated according to tumor size and grade. We compared the SUVmax for different insulinoma grades and analyzed the correlation of SUVmax with Ki-67, maximum tumor diameter, and glucose metabolism indicators. Results The study included 12 grade (G) 1 and 16 G2 cases, with maximum tumor diameters ranging from 9 to 40 mm. Without differentiation by size and grade, the sensitivity of Exendin-4 PET/CT to localize insulinoma was 100%, which significantly exceeded that of 68 Ga-DOTATATE PET/CT and 18 F-FDG PET/CT (75% and 57%, respectively). In tumors with a maximum diameter ≤ 20 mm and ≤ 15 mm, the sensitivity of Exendin-4 (both 100%) significantly exceeded that of 68 Ga-DOTATATE PET/CT (74% and 64%, respectively) and 18 F-FDG PET/CT (54% and 50%, respectively). In G1 tumors, the sensitivity of Exendin-4 PET/CT was significantly higher than that of 18 F-FDG PET/CT, but not that of 68 Ga-DOTATATE PET/CT, while in G2 tumors, the sensitivity of Exendin-4 PET/CT was significantly higher than that of both other types. However, all three PET/CT types missed a metastatic lymph node in one patient. The 18 F-FDG PET/CT SUVmax was significantly lower than that of the other PET/CT types and that of 68 Ga-DOTATATE PET/CT was significantly lower in G2 than in G1. 68 Ga-DOTATATE PET/CT SUVmax correlated negatively with Ki-67. A receiver operating characteristic (ROC) curve suggested that 68 Ga-DOTATATE PET/CT SUVmax > 19.9 could predict G1 tumors. Conclusion Exendin-4 PET/CT was superior to 68 Ga-DOTATATE PET/CT and 18 F-FDG PET/CT for insulinoma localization, particularly small and G2 tumors, but its diagnostic value in small metastatic lymph nodes requires further exploration. 68 Ga-DOTATATE PET/CT SUVmax could be used as an adjunct to pathology, and a value > 19.9 could predict G1 tumors. No PET/CT SUVmax could predict tumor maximum diameter and glucose metabolism.