Specificity of translocator protein-targeted positron emission tomography in inflammatory joint disease
File(s)
Published version
Author(s)
Helo, Y
Searle, GE
Borgheese, F
Abraham, Sonya
Azeem, Saleem
Type
Journal Article
Abstract
Objective
Expression of the translocator protein (TSPO) on inflammatory cells has facilitated imaging of synovitis with TSPO-targeted positron emission tomography (PET). We aimed to quantitatively assess the specificity of the second-generation TSPO PET radioligand, [11C]PBR28, and to generate simplified PET protocols in patients with inflammatory joint disease (IJD) in this pilot study.
Methods
Three IJD patients (two rheumatoid arthritis and one osteoarthritis) with knee involvement underwent dynamic [11C]PBR28-PET scans before and after administration of 90 mg of oral emapunil (XBD-173), a TSPO ligand the same day. Radial arterial blood sampling was performed throughout the scan, and total radioactivity and radioactive metabolites were obtained. A semi-automated method was used to generate regions of interest. Standardized uptake value (SUV) and SUV ratio corrected for activity in bone and blood between 50 and 70 min (SUVr50–70 bone, SUVr50–70 blood, respectively) and PET volume of distribution (VT) of the radioligand were calculated.
Results
A mean [11C]PBR28 radioactivity of 378 (range 362–389) MBq was administered. A significant decrease (p < 0.05) in VT, SUVr50–70 bone and SUVr50–70 blood observed after oral emapunil confirmed the TSPO specificity of [11C]PBR28. A decrease in SUV was not observed in the post-block scan.
Conclusion
[11C]PBR28 is TSPO-specific radioligand in IJD patients. Simplified PET protocols with static PET acquisition can be used in the management and evaluation of novel therapeutics that target TSPO overexpressing cells.
Expression of the translocator protein (TSPO) on inflammatory cells has facilitated imaging of synovitis with TSPO-targeted positron emission tomography (PET). We aimed to quantitatively assess the specificity of the second-generation TSPO PET radioligand, [11C]PBR28, and to generate simplified PET protocols in patients with inflammatory joint disease (IJD) in this pilot study.
Methods
Three IJD patients (two rheumatoid arthritis and one osteoarthritis) with knee involvement underwent dynamic [11C]PBR28-PET scans before and after administration of 90 mg of oral emapunil (XBD-173), a TSPO ligand the same day. Radial arterial blood sampling was performed throughout the scan, and total radioactivity and radioactive metabolites were obtained. A semi-automated method was used to generate regions of interest. Standardized uptake value (SUV) and SUV ratio corrected for activity in bone and blood between 50 and 70 min (SUVr50–70 bone, SUVr50–70 blood, respectively) and PET volume of distribution (VT) of the radioligand were calculated.
Results
A mean [11C]PBR28 radioactivity of 378 (range 362–389) MBq was administered. A significant decrease (p < 0.05) in VT, SUVr50–70 bone and SUVr50–70 blood observed after oral emapunil confirmed the TSPO specificity of [11C]PBR28. A decrease in SUV was not observed in the post-block scan.
Conclusion
[11C]PBR28 is TSPO-specific radioligand in IJD patients. Simplified PET protocols with static PET acquisition can be used in the management and evaluation of novel therapeutics that target TSPO overexpressing cells.
Date Issued
2020-12-07
Date Acceptance
2020-11-17
Citation
EJNMMI Research, 2020, 10
ISSN
2191-219X
Publisher
Springer
Journal / Book Title
EJNMMI Research
Volume
10
Copyright Statement
© The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Subjects
Science & Technology
Life Sciences & Biomedicine
Radiology, Nuclear Medicine & Medical Imaging
1101 Medical Biochemistry and Metabolomics
1103 Clinical Sciences
1112 Oncology and Carcinogenesis
Publication Status
Published
Article Number
ARTN 147