Abstract
BACKGROUND: Somatostatin receptor (SSTR)-targeted PET is valuable for meningioma imaging due to high SSTR expression. [(18)F]SiTATE, a novel tracer, is not only promising for imaging neuroendocrine tumors but also for meningiomas. Standardized delineation methods on [(18)F]SiTATE PET are lacking. This study correlates CT-based volumes with PET-based delineation approaches to identify a threshold for standardized [(18)F]SiTATE PET volume assessment. METHODS: Patients with well-delineated, extraosseous meningioma on CT (≥ 1mL) who underwent [(18)F]SiTATE PET/CT were included. Volumes were assessed on contrast-enhanced CT and correlated with PET-based delineation approaches: (I) fixed SUV threshold, (II) isocontour thresholding relative to SUV(max) (SUV%), and thresholds relative to (III) bone marrow (SUV(BM)), (IV) parotid gland (SUV(parotis)) and (V) pituitary gland (SUV(sella)). RESULTS: 19 meningiomas in 17 PET/CT scans (16 patients) were included. A fixed SUV of 4.0 (r = 0.783, p < 0.001) showed good correlation with CT volumes without skewed distribution on Bland-Altman-Plot analysis. Using isocontour-based thresholds, 45% SUV(max) (r = 0.496, p = 0.031) showed the highest concordance. Best reference-based approaches were achieved by 150% SUV(BM) (r = 0.859, p < 0.001), 250% SUV(parotis) (r = 0.460, p = 0.047) and 70% SUV(sella) (r = 0.819, p < 0.001). However, background-based approaches showed a trend towards overestimation of PET-volumes in larger meningiomas as assessed on Bland-Altman-Plot analyses. Uptake intensities of reference tissues (SUV(BM,) SUV(parotis) and SUV(sella)) were not inter-correlated (p > 0.05 each). CONCLUSION: A fixed SUV threshold of 4.0 showed strong agreement with CT-based volumes in well-delineated, extraosseous meningiomas which offers a simple, clinically applicable method without technical requirements. Reference tissue-based methods showed similar correlations but tended to overestimate volumes in larger lesions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12672-025-04079-6.