[18F]SiTATE ([18F]SiFAlin-TATE) is a SiFAlin tagged [Tyr3]-octreotate (TATE) radioligand for imaging of somatostatin receptor (SSTR). Somatostatin receptor imaging can be used in neuroendocrine tumour (NET) imaging.

SiTATE is highly selective for the SSTR subtype 2 (1.0 nM) with only minor affinity to the SSTR3 and SSTR4 (712 nM and 364 nM) and nearly no affinity to the SSTR subtype 1 and 5 (> 10.000 nM and > 1.000 nM), which distinguishes SiTATE from [Ga-68]DOTATOC, which has a moderate affinity towards the SSTR5 (Wängler et al., 2022). SSTR2 is be predominantly expressed in most neuroblastomas, meningiomas, medulloblastomas, breast carcinomas, lymphomas, renal cell carcinomas, paragangliomas, small cell lung carcinomas, and hepatocellular carcinomas (Reubi et al., 2001).

The total effective dose from [18F]SiTATE PET is 0.015 ± 0.004 mSv/MBq, which is comparable to 68Ga-labelled SSTR radioligands (Beyer et al., 2021).

[18F]SiTATE has a fast blood pool washout over time, and normal organs show only minimal 18F concentration changes between 1 and 3 h post-injection, while SUV continued to increase in most metastases (Beyer et al., 2021). Tumour-to-liver and tumour-to-spleen ratios are comparable to those of [68Ga]Ga-DOTATOC (Ilhan et al., 2020). For clinical use of [18F]SiTATE, the best compromise between image quality and tumour-to-background contrast is reached at 120 min (Beyer et al., 2021).

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Beyer L, Gosewisch A, Lindner S, Völter F, Mittlmeier LM, Tiling R, Brendel M, Cyran CC, Unterrainer M, Rübenthaler J, Auernhammer CJ, Spitzweg C, Böning G, Gildehaus FJ, Jurkschat K, Wängler C, Wängler B, Schirrmacher R, Wenter V, Todica A, Bartenstein P, Ilhan H. Dosimetry and optimal scan time of [18F]SiTATE-PET/CT in patients with neuroendocrine tumours. Eur J Nucl Med Mol Imaging 2021; 48(11): 3571-3581. doi: 10.1007/s00259-021-05351-x.

Ilhan H, Lindner S, Todica A, Cyran CC, Tiling R, Auernhammer CJ, Spitzweg C, Boeck S, Unterrainer M, Gildehaus FJ, Böning G, Jurkschat K, Wängler C, Wängler B, Schirrmacher R, Bartenstein P. Biodistribution and first clinical results of 18F-SiFAlin-TATE PET: a novel 18F-labeled somatostatin analog for imaging of neuroendocrine tumors. Eur J Nucl Med Mol Imaging 2020; 47(4): 870-880. doi: 10.1007/s00259-019-04501-6.

Niedermoser S, Chin J, Wängler C, Kostikov A, Bernard-Gauthier V, Vogler N, Soucy JP, McEwan AJ, Schirrmacher R, Wängler B. In vivo evaluation of 18F-SiFAlin-modified TATE: A potential challenge for 68Ga-DOTATATE, the clinical gold standard for somatostatin receptor imaging with PET. J Nucl Med. 2015; 56(7): 1100-1105. doi: 10.2967/jnumed.114.149583.

Wängler C, Beyer L, Bartenstein P, Wängler B, Schirrmacher R, Lindner S. Favorable SSTR subtype selectivity of SiTATE: new momentum for clinical [18F]SiTATE PET. EJNMMI Radiopharm Chem. 2022; 7(1): 22. doi: 10.1186/s41181-022-00176-x.

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Updated at: 2022-12-07
Created at: 2022-12-07
Written by: Vesa Oikonen