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Background: Somatostatin-receptor (SSTR)-targeted PET/CT provides important clinical information in addition to standard imaging in meningioma patients. [ 18 F]SiTATE is a novel, 18 F-labeled SSTR-targeting peptide with superior imaging properties according to preliminary data. We provide the first [ 18 F]SiTATE PET/CT data of a large cohort of meningioma patients., Methods: Patients with known or suspected meningioma undergoing [ 18 F]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 [ 18 F]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 18 F-labeled SSTR-ligand in meningioma patients: [ 18 F]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 18 F-labeled compared to 68 Ga-labeled compounds (e.g., longer half-life and large-badge production), [ 18 F]SiTATE has the potential to foster a widespread use of SSTR-targeted imaging in neuro-oncology., (© 2023. The Author(s).)

Abstract: PET using 68Ga-labeled somatostatin receptor (SSTR) ligands adds significant information in meningioma patients. 18F-SiTATE is a novel, 18F-labeled SSTR-targeting peptide with remarkable imaging properties. Here, we present a 72-year-old woman with falx meningioma and transosseous extension. 18F-SiTATE PET/CT was performed 12 months after the previous 68Ga-DOTATOC PET/CT with comparable quantitative uptake and very good spatial resolution. So far, the widespread use of SSTR ligands for NET and meningioma imaging is hampered by cost-intensive 68Ge/68Ga generators, low activity amounts, lower spatial resolution, and short half-life. 18F-SiTATE might foster widespread use of SSTR ligands, overcoming the shortcomings of 68Ga-labeled ligands., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Surgeon's intraoperative estimation of meningioma extent of resection (Simpson Grade, SG) is widely used as a prognostic factor for recurrence. However, the validity of SG is still a matter of debate. In preoperative imaging, 68Ga-DOTATATE/PET-CT has been shown to detect meningioma tissue even more sensitively than magnetic resonance imaging (MRI)., Objective: To evaluate the Simpson grading within the framework of modern postoperative imaging techniques (MRI; PET-CT)., Methods: At first, patients with WHO grade I meningioma, surgical resection, and postoperative 68Ga-DOTATATE/PET-CT within 6 mo after surgery were retrospectively analyzed. Second, an analogous prospective cohort of patients with WHO grade I meningioma was investigated by comparing SG after meningioma removal with postoperative MRI and 68Ga-DOTATATE/PET-CT within 6 mo after surgery., Results: A total of 37 patients were retrospectively analyzed. In total, 5/8 patients with SG-I and II resections showed tumor remnants according to postoperative PET-CT (SG 62.5% false negative). In the prospective cohort of 52 tumors, PET-CT displayed tracer uptake in 15/37 SG-I or II resections indicating unexpected tumor remnants (SG 40.5% false negative). MRI was false negative in 7 of these 15 cases (MRI 18.9% false negative) (P = .037). Discordant results according to PET-CT were more often found in convexity (40%) and falcine (46.7%) meningiomas than in skull base meningiomas (18.2%)., Conclusion: Intraoperative Simpson grading is at risk to underestimate tumor remnants, predominantly in grade I and II resections. Postoperative PET-CT improves detection rates compared to MRI. Prognostic impact of postoperative meningioma remnants according to PET-CT needs to be investigated prospectively., (Copyright © 2020 by the Congress of Neurological Surgeons.)

A 77-year-old woman with history of breast cancer presented with 2 unclear dural contrast-enhancing lesions on MRI; differential diagnoses were breast cancer metastases and meningiomas. On Ga-DOTATOC PET/CT, the temporal lesion showed high uptake and was classified as meningioma, whereas the lesion at the falx showed barely any Ga-DOTATOC uptake uncharacteristic for meningioma and suggestive for a brain metastasis. After resection, histological specimens from the temporal lesion showed meningioma tissue with distinct SSTR2A expression, whereas the falx lesion revealed a breast cancer metastasis without significant SSTR2A expression. Therefore, Ga-DOTATOC PET represents a powerful imaging modality for the evaluation of unclear dural lesions.

A 43-year-old woman with suspected recurrence of atypical meningioma World Health Organization grade II presented extensive intracranial lesions with high Ga-DOTATATE uptake. Moreover, numerous Ga-DOTATATE-positive bone, lung, and liver lesions were seen. For final diagnosis, biopsies taken from a lung lesion revealed distant metastases of the atypical meningioma. This case underlines the high diagnostic power of Ga-DOTATATE PET/CT for the staging of meningioma even beyond cerebral or spinal lesions; in case of distant lesions in patients with known meningioma, differential diagnosis should also contain metastases despite their rare occurrence. Moreover, this case emphasizes radioligand therapy especially in metastatic meningioma.

In this case of suspected sphenoid wing meningioma, Ga-DOTATATE PET/CT showed a somatostatin receptor (SSR)-expressing tumor with extension to the nasopharynx and SSR-expressing cervical lymph nodes. Subsequent biopsy from the nasopharynx revealed an Epstein-Barr virus (EBV)-associated, undifferentiated World Health Organization type 3 nasopharyngeal carcinoma (NPC), a potential clinical pitfall due to the reported high SSR expression of this tumor subtype. In consideration of the high target-to-background contrast, SSR ligands might be superior to F-FDG for EBV-associated NPC PET imaging, particularly at the skull base. Somatostatin receptor ligands might furthermore offer interesting theranostic possibilities for patients with advanced/extensive EBV-associated NPC.

We report a woman with multifocal lesions suggestive of meningiomas in MRI, which also presented with high Ga-DOTATATE uptake in PET, a finding characteristic for meningioma. A whole-body staging due to a pathological fracture revealed multiple neoplastic lesions throughout the body without detection of a primary site. Subsequent pathological workup of a lung lesion revealed multifocal metastases from follicular thyroid cancer despite thyroidectomy 10 years ago (without pathological finding), and posttreatment scans after radioiodine therapy confirmed the multiple brain lesions to be metastases as well. Our case shows that epidural metastases from endocrine origin might represent a clinical pitfall in Ga-DOTATATE PET.