Vol.:(0123456789) 1 3 Molecular Imaging and Biology https://doi.org/10.1007/s11307-022-01776-4 RESEARCH ARTICLE [ 18 F]FDG Uptake and Expression of Immunohistochemical Markers Related to Glycolysis, Hypoxia, and Proliferation in Indeterminate Thyroid Nodules Elizabeth J. de Koster 1  · Adriana C. H. van Engen‑van Grunsven 2  · Johan Bussink 3  · Cathelijne Frielink 1  · Lioe‑Fee de Geus‑Oei 1,4,5  · Benno Kusters 2  · Hans Peters 3  · Wim J. G. Oyen 1,6,7  · Dennis Vriens 4  · On behalf of the EFFECTS trial study group Received: 11 July 2022 / Revised: 21 September 2022 / Accepted: 23 September 2022 © The Author(s) 2022 Abstract Purpose The current study explored the association between 2-[ 18 F]fuoro-2-deoxy-D-glucose ([ 18 F]FDG) uptake and the quantitative expression of immunohistochemical markers related to glucose metabolism, hypoxia, and cell proliferation in benign and malignant thyroid nodules of indeterminate cytology. Procedures Using a case–control design, 24 patients were selected from participants of a randomized controlled multicenter trial (NCT02208544) in which [ 18 F]FDG-PET/CT and thyroid surgery were performed for Bethesda III and IV nodules. Three equally sized groups of [ 18 F]FDG-positive malignant, [ 18 F]FDG-positive benign, and [ 18 F]FDG-negative benign nodules were included. Immunohistochemical staining was performed for glucose transporters (GLUT) 1, 3, and 4; hexokinases (HK) 1 and 2; hypoxia- inducible factor-1 alpha (HIF1α; monocarboxylate transporter 4 (MCT4); carbonic anhydrase IX (CA-IX); vascular endothelial growth factor (VEGF); sodium-iodide symporter (NIS); and Ki-67. Marker expression was scored using an immunoreactive score. Unsupervised cluster analysis was performed. The immunoreactive score was correlated to the maximum and peak standardized uptake values (SUV max , SUV peak ) and SUV max ratio (SUV max of nodule/background SUV max of contralateral, normal thyroid) of the [ 18 F]FDG-PET/CT using the Spearman’s rank correlation coefcient and compared between the three groups using Kruskal–Wallis tests. Results The expression of GLUT1, GLUT3, HK2, and MCT4 was strongly positively correlated with the SUV max , SUV peak , and SUV max ratio. The expression of GLUT1 (p = 0.009), HK2 (p = 0.02), MCT4 (p = 0.01), and VEGF (p = 0.007) was statisti- cally signifcantly diferent between [ 18 F]FDG-positive benign nodules, [ 18 F]FDG-positive thyroid carcinomas, and [ 18 F]FDG- negative benign nodules. In both [ 18 F]FDG-positive benign nodules and [ 18 F]FDG-positive thyroid carcinomas, the expression of GLUT1, HK2, and MCT4 was increased as compared to [ 18 F]FDG-negative benign nodules. VEGF expression was higher in [ 18 F]FDG-positive thyroid carcinomas as compared to [ 18 F]FDG-negative and [ 18 F]FDG-positive benign nodules. Conclusions Our results suggest that [ 18 F]FDG-positive benign thyroid nodules undergo changes in protein expression simi- lar to those in thyroid carcinomas. To expand the understanding of the metabolic changes in benign and malignant thyroid nodules, further research is required, including correlation with underlying genetic alterations. Key words Thyroid Nodule · [ 18 F]FDG-PET/CT · Immunohistochemistry · Glycolysis · Glucose Metabolism Introduction Positron emission tomography/computed tomography (PET/CT) using the glucose analogue 2-[ 18 F]fluoro- 2-deoxy-D-glucose ([ 18 F]FDG) visualizes (increased) metabolic activity in tissues and is successfully applied for the diagnosis, staging, and monitoring of many types of cancers and infammatory disorders [1]. [ 18 F]FDG-PET/ CT exploits the Warburg efect, a well-known phenomenon in oncology describing the altered metabolism in malig- nancies: as compared to a low rate of glycolysis followed by oxidative phosphorylation in normal tissues, increased glycolysis and lactic fermentation is observed in cancer, * Elizabeth J. de Koster Lisanne.deKoster@radboudumc.nl Extended author information available on the last page of the article