Carlier Thomas, Gnesin Silvano, Mikell Justin K, Conti Maurizio, Prior John O, Schaefer Niklaus, Pérez Lago Maria Del Sol, Bailly Clément, Dewaraja Yuni K, Lima Thiago V M
Nuclear Medicine Department, University Hospital of Nantes, Nantes, France.
Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
EJNMMI Phys. 2025 Feb 5;12(1):12. doi: 10.1186/s40658-025-00725-8.
Therapeutic administration of Y-loaded microspheres is routinely used for primary and secondary liver tumours. For activity-based therapeutic prescription the activity must be within 10% of the intended activity. Previous studies reported significant discrepancies between manufacturer-declared vial activities and both experimental and Monte-Carlo assessments, greater than 10%, for resin/glass Y-microspheres. The objective of this work was to investigate whether these discrepancies were also seen in patients.
We analysed patient Y-PET reconstructions (99 glass and 15 resin microspheres) from 4 different institutions and 4 different systems. We considered tail-fitting background scaling (TFBS) and absolute scaling (ABS), for scatter correction. Residuals after therapeutic injection were measured. Eighty-one patients were imaged with PET/CT and 33 with PET/MR. The PET measured activity (A) was assessed in the whole liver. The ratio A/A was calculated for each patient, where A was the injected activity measured by the dose calibrator corrected for residual and lung shunt.
Quantification ratio between calibrators and PET was significantly different from 1, regardless of the scatter correction used. In glass microspheres, the mean A/A was 0.84 ± 0.06 for TFBS and 0.90 ± 0.06 for ABS (0.66 ± 0.09 and 0.76 ± 0.07 for (A/A)). The mean A/A ratio for resin microspheres was 1.16 ± 0.09 for TFBS and 1.30 ± 0.12 for ABS.
We observed in patients similar activity discrepancies as reported for vials, with a relative difference of 44 ± 16% between glass and resin Y-loaded microspheres. In Y hepatic radioembolization, the 10% accuracy prerequisite on knowing the administered therapeutic activity is then unlikely to be met.
负载钇的微球的治疗性给药通常用于原发性和继发性肝肿瘤。对于基于活性的治疗处方，活性必须在预期活性的10%以内。先前的研究报告称，对于树脂/玻璃钇微球，制造商声明的瓶内活性与实验评估和蒙特卡罗评估之间存在显著差异，超过了10%。这项工作的目的是调查这些差异在患者中是否也存在。
我们分析了来自4个不同机构和4种不同系统的患者钇正电子发射断层扫描（PET）重建图像（99个玻璃微球和15个树脂微球）。我们考虑了用于散射校正的尾部拟合背景缩放（TFBS）和绝对缩放（ABS）。测量治疗性注射后的残差。81名患者接受了PET/CT成像，33名患者接受了PET/MR成像。在整个肝脏中评估PET测量的活性（A）。计算每位患者的A/A比值，其中A是通过剂量校准器测量的注射活性，并针对残差和肺分流进行了校正。
无论使用何种散射校正，校准器与PET之间的定量比值均显著不同于1。在玻璃微球中，TFBS的平均A/A为0.84±0.06，ABS的平均A/A为0.90±0.06（（A/A）分别为0.66±0.09和0.76±0.07）。树脂微球的平均A/A比值，TFBS为1.16±0.09，ABS为1.30±0.12。
我们在患者中观察到与瓶内报告的类似的活性差异，负载钇的玻璃微球和树脂微球之间的相对差异为44±16%。在钇肝动脉栓塞治疗中，不太可能满足知道给药治疗活性的10%准确性的先决条件。
