Next-generation PET/CT imaging in meningioma-first clinical experiences using the novel SSTR-targeting peptide [18F]SiTATE

Abstract

Background: Somatostatin-receptor (SSTR)-targeted PET/CT provides important clinical information in addition to standard imaging in meningioma patients. [¹⁸F]SiTATE is a novel, ¹⁸F-labeled SSTR-targeting peptide with superior imaging properties according to preliminary data. We provide the first [¹⁸F]SiTATE PET/CT data of a large cohort of meningioma patients.

Methods: Patients with known or suspected meningioma undergoing [¹⁸F]SiTATE PET/CT were included. Uptake intensity (SUV) of meningiomas, non-meningioma lesions, and healthy organs were assessed using a 50% isocontour volume of interest (VOI) or a spherical VOI, respectively. Also, trans-osseous extension on PET/CT was assessed.

Results: A total of 107 patients with 117 [¹⁸F]SiTATE PET/CT scans were included. Overall, 231 meningioma lesions and 61 non-meningioma lesions (e.g., post-therapeutic changes) were analyzed. Physiological uptake was lowest in healthy brain tissue, followed by bone marrow, parotid, and pituitary (SUV_mean 0.06 ± 0.04 vs. 1.4 ± 0.9 vs. 1.6 ± 1.0 vs. 9.8 ± 4.6; p < 0.001). Meningiomas showed significantly higher uptake than non-meningioma lesions (SUV_max 11.6 ± 10.6 vs. 4.0 ± 3.3, p < 0.001). Meningiomas showed significantly higher uptake than non-meningioma lesions (SUVmax 11.6±10.6 vs. 4.0±3.3, p<0.001). 93/231 (40.3%) meningiomas showed partial trans-osseous extension and 34/231 (14.7%) predominant intra-osseous extension. 59/231 (25.6%) meningioma lesions found on PET/CT had not been reported on previous standard imaging.

Conclusion: This is the first PET/CT study using an ¹⁸F-labeled SSTR-ligand in meningioma patients: [¹⁸F]SiTATE provides extraordinary contrast in meningioma compared to healthy tissue and non-meningioma lesions, which leads to a high detection rate of so far unknown meningioma sites and osseous involvement. Having in mind the advantageous logistic features of ¹⁸F-labeled compared to ⁶⁸Ga-labeled compounds (e.g., longer half-life and large-badge production), [¹⁸F]SiTATE has the potential to foster a widespread use of SSTR-targeted imaging in neuro-oncology.

Keywords: Meningioma; PET; SiTATE; Somatostatin receptor (SSTR).

Fig. 1

Structural formula [¹⁸F]SiTATE, see analogously [8]

Fig. 2

A 64-year-old with residual transitional meningioma, CNS WHO grade 1 at the right tentorium (A) with strong SSTR-expression (SUV_max 21.4), but also signs of chronic sinusitis at the right sinus maxillaris (B) with moderate SSTR-expression due to chronic inflammation (SUV_max 8.1)

Fig. 3

A case of a 51-year-old man with newly diagnosed occipital meningioma, which also showed infiltration of the super sagittal sinus with partial thrombosis and a trans-osseous extension within the occipital bone to the right side, which is easily detectable on [¹⁸F]SiTATE PET due to the strong SSTR expression (SUV_max 11.9). Resection revealed a CNS WHO grade 1 transitional meningioma

Fig. 4

Follow-up imaging using [¹⁸F]SiTATE PET imaging: a patient with residual tumor remnant with extension to the superior sagittal sinus. The lesion at the superior sagittal sinus showed strong SSTR expression on [¹⁸F]SiTATE (A, SUV_max 8.6) without relevant changes in the course of 38 months without tumor-specific treatment. SSTR-expression on [⁶⁸Ga]Ga-DOTATOC was comparable in the previous medical history (B, SUV_max 6.1)