Measurement of 68 Ga-DOTATOC Uptake in the Thoracic Aorta and Its Correlation with Cardiovascular Risk.

Purpose: ⁶⁸ Ga-labeled 1,4,7,10-tetraazacyclododecane- N , N ', N ″, N ‴-tetraacetic acid-d-Phe ¹ -Tyr ³ -octreotide ( ⁶⁸ Ga-DOTATOC) is taken up by activated macrophages, which accumulate in active inflammatory lesions. The purpose of this study was to investigate the feasibility of ⁶⁸ Ga-DOTATOC PET/CT for assessment of vulnerable plaque, by evaluating correlation between aortic uptake of ⁶⁸ Ga-DOTATOC and cardiovascular risk factors.
Methods: Fifty patients with neuroendocrine tumors who underwent ⁶⁸ Ga-DOTATOC PET/CT were retrospectively enrolled. The uptakes in the thoracic aorta were measured by two methods: multi-sample region-of-interest (ROI) method and single volume-of-interest (VOI) method. TBR _max-avg , TBR _mean-avg , TBR _max-VOI , and TBR _mean-VOI were defined by maximum and mean target-to-background ratio (TBR) from the multi-sample ROI method and the single VOI method, respectively.
Results: Framingham risk score (FRS) exhibited significant correlations with TBR _max-avg and TBR _mean-avg , as well as TBR _max-VOI ( r  = 0.3389-0.4593, P  < 0.05 for all). TBR _max-avg and TBR _max-VOI were significantly higher in high FRS group than in low FRS group (1.48 ± 0.21 vs. 1.70 ± 0.17, P  < 0.001 for TBR _max-avg and 1.90 ± 0.33 vs. 2.25 ± 0.36, P  = 0.002 for TBR _max-VOI ). TBR exhibited high correlations between the two measuring methods ( r  = 0.9684, P  < 0.001 for TBR _mean-avg and TBR _mean-VOI and r  = 0.8681, P  < 0.001 for TBR _max-avg and TBR _max-VOI ).
Conclusions: ⁶⁸ Ga-DOTATOC uptake in the thoracic aorta exhibited a significant correlation with cardiovascular risk factors, which suggests the feasibility of ⁶⁸ Ga-DOTATOC PET for vulnerable plaque imaging, with a simple measurement of the single VOI method that is comparable to the multi-sample ROI-based approach.
Competing Interests: Compliance with Ethical StandardsLee Reeree, Jihyun Kim, Jin Chul Paeng, Jung Woo Byun, Gi Jeong Cheon, Dong Soo Lee, June-Key Chung, and Keon Wook Kang declare that they have no conflict of interest.All procedures followed were performed in accordance with the ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration of 1975, as revised in 2013. The study design was approved by the Institutional Review Board of the Seoul National University Hospital (H-1711-112-901). This manuscript has not been published before or is not under consideration for publication anywhere else and has been approved by all co-authors.The study design of the retrospective analysis and exemption of informed consent were approved by the Institutional Review Board of the Seoul National University Hospital.