Grob Dagmar, Privé Bastiaan M, Muselaers Constantijn H J, Mehra Niven, Nagarajah James, Konijnenberg Mark W, Peters Steffie M B
Department of Medical Imaging, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
Department of Healthcare and Information Technology, Slingeland Hospital, Doetinchem, The Netherlands.
EJNMMI Phys. 2024 Apr 3;11(1):34. doi: 10.1186/s40658-024-00636-0.
Bone marrow toxicity in advanced prostate cancer patients who receive [Lu]Lu-PSMA-617 is a well-known concern. In early stage patients; e.g. low volume metastatic hormone sensitive prostate cancer (mHSPC) patients, prevention of late bone marrow toxicity is even more crucial due to longer life expectancy. To date, bone marrow dosimetry is primarily performed using blood sampling. This method is time consuming and does not account for possible active bone marrow uptake. Therefore other methodologies are investigated. We calculated the bone marrow absorbed dose for [Lu]Lu-PSMA-617 in mHSPC patients using SPECT/CT imaging and compared it to the blood sampling method as reference.
Eight mHSPC patients underwent two cycles (3 and 6 GBq) of [Lu]Lu-PSMA-617 therapy. After each cycle, five time point (1 h, 1 day, 2 days, 3 days, 7 days) SPECT/CT was performed at kidney level. Bone marrow dosimetry was performed using commercial software by drawing ten 1.5 cm diameter spheres in the lowest ten vertebrae to determine the time-integrated activity. Simplified protocols using only 2 imaging time points and 3 vertebrae were also compared. Blood-based dosimetry was based on the blood sampling method according to the EANM guideline.
Mean bone marrow absorbed dose was significantly different (p < 0.01) for the imaging based method (25.4 ± 8.7 mGy/GBq) and the blood based method (17.2 ± 3.4 mGy/GBq), with an increasing absorbed dose ratio between both methods over time. Bland Altman analysis of both simplification steps showed that differences in absorbed dose were all within the 95% limits of agreement.
This study showed that bone marrow absorbed dose after [Lu]Lu-PSMA-617 can be determined using an imaging-based method of the lower vertebrae, and simplified using 2 time points (1 and 7 days) and 3 vertebrae. An increasing absorbed dose ratio over time between the imaging-based method and blood-based method suggests that there might be specific bone marrow binding of [Lu]Lu-PSMA-617.
接受[镥]镥-PSMA-617治疗的晚期前列腺癌患者的骨髓毒性是一个众所周知的问题。在早期患者中，例如低容量转移性激素敏感性前列腺癌（mHSPC）患者，由于预期寿命较长，预防晚期骨髓毒性更为关键。迄今为止，骨髓剂量测定主要通过采血进行。这种方法耗时且未考虑骨髓可能的活性摄取。因此，人们正在研究其他方法。我们使用SPECT/CT成像计算了mHSPC患者中[镥]镥-PSMA-617的骨髓吸收剂量，并将其与作为参考的采血方法进行比较。
8例mHSPC患者接受了两个周期（3和6GBq）的[镥]镥-PSMA-617治疗。每个周期后，在肾脏水平进行五个时间点（1小时、1天、2天、3天、7天）的SPECT/CT检查。使用商业软件通过在最低的十个椎骨中绘制十个直径为1.5厘米的球体来进行骨髓剂量测定，以确定时间积分活度。还比较了仅使用2个成像时间点和3个椎骨的简化方案。基于血液的剂量测定是根据EANM指南的采血方法进行的。
基于成像的方法（25.4±8.7mGy/GBq）和基于血液的方法（17.2±3.4mGy/GBq）的平均骨髓吸收剂量有显著差异（p<0.01），两种方法之间的吸收剂量比随时间增加。对两个简化步骤的布兰德-奥特曼分析表明，吸收剂量的差异均在95%一致性界限内。
本研究表明，[镥]镥-PSMA-617后的骨髓吸收剂量可以使用基于下椎骨成像的方法来确定，并可简化为使用2个时间点（1天和7天）和3个椎骨。基于成像的方法和基于血液的方法之间的吸收剂量比随时间增加，这表明[镥]镥-PSMA-617可能与骨髓有特异性结合。
