Department of Nuclear Medicine, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany.
Department of Radiology, University Hospital, LMU Munich, Munich, Germany.
Eur J Nucl Med Mol Imaging. 2021 Oct;48(11):3571-3581. doi: 10.1007/s00259-021-05351-x. Epub 2021 Apr 29.
Radiolabelled somatostatin analogues targeting somatostatin receptors (SSR) are well established for combined positron emission tomography/computer tomography (PET/CT) imaging of neuroendocrine tumours (NET). [F]SiTATE has recently been introduced showing high image quality, promising clinical performance and improved logistics compared to the clinical reference standard Ga-DOTA-TOC. Here we present the first dosimetry and optimal scan time analysis.
Eight NET patients received a [F]SiTATE-PET/CT (250 ± 66 MBq) with repeated emission scans (10, 30, 60, 120, 180 min after injection). Biodistribution in normal organs and SSR-positive tumour uptake were assessed. Dosimetry estimates for risk organs were determined using a combined linear-monoexponential model, and by applying F S-values and reference target masses for the ICRP89 adult male or female (OLINDA 2.0). Tumour-to-background ratios were compared quantitatively and visually between different scan times.
After 1 h, normal organs showed similar tracer uptake with only negligible changes until 3 h post-injection. In contrast, tracer uptake by tumours increased progressively for almost all types of metastases, thus increasing tumour-to-background ratios over time. Dosimetry resulted in a total effective dose of 0.015 ± 0.004 mSv/MBq. Visual evaluation revealed no clinically relevant discrepancies between later scan times, but image quality was rated highest in 60 and 120 min images.
[F]SiTATE-PET/CT in NET shows overall high tumour-to-background ratios from 60 to 180 min after injection and an effective dose comparable to Ga-labelled alternatives. For clinical use of [F]SiTATE, the best compromise between image quality and tumour-to-background contrast is reached at 120 min, followed by 60 min after injection.
针对生长抑素受体（SSR）的放射性标记生长抑素类似物已被广泛用于神经内分泌肿瘤（NET）的正电子发射断层扫描/计算机断层扫描（PET/CT）联合成像。[F]SiTATE 最近被引入，与临床参考标准 Ga-DOTA-TOC 相比，其具有更高的图像质量、更有前景的临床性能和改进的物流。在此，我们首次进行了放射性配体治疗剂量学和最佳扫描时间分析。
8 名 NET 患者接受了[F]SiTATE-PET/CT（250±66MBq）检查，在注射后 10、30、60、120、180 分钟进行了重复发射扫描。评估了正常器官的生物分布和 SSR 阳性肿瘤摄取情况。使用组合线性单指数模型和 ICRP89 成年男性或女性（OLINDA 2.0）的 F S 值和参考靶质量来确定风险器官的剂量学估算值。在不同扫描时间之间进行了定量和视觉比较，以比较肿瘤与背景的比值。
在 1 小时后，正常器官的示踪剂摄取相似，仅在注射后 3 小时内出现可忽略的变化。相比之下，几乎所有类型的转移瘤中示踪剂摄取都逐渐增加，从而随着时间的推移增加了肿瘤与背景的比值。剂量学结果导致总有效剂量为 0.015±0.004mSv/MBq。视觉评估显示，在不同的扫描时间之间没有临床相关的差异，但在 60 和 120 分钟的图像中，图像质量被评为最高。
在 NET 中，[F]SiTATE-PET/CT 在注射后 60 至 180 分钟显示出总体上较高的肿瘤与背景比值，并且有效剂量与 Ga 标记的类似物相当。对于[F]SiTATE 的临床应用，在注射后 120 分钟时达到了图像质量和肿瘤与背景对比度之间的最佳折衷，其次是 60 分钟。
