Swailem F M, Krishnamurthy G T, Srivastava S C, Aguirre M L, Ellerson D L, Walsh T K, Simpson L, Shah J
VA Medical Center and Dept. of Radiology, University of Arizona School of Medicine, Tucson 85723, USA.
Nucl Med Biol. 1998 Apr;25(3):279-87. doi: 10.1016/s0969-8051(97)00180-7.
Organ and tissue uptake and retention of Sn-117m(4+)DTPA were studied in a human subject treated for metastatic bone pain, and the results were compared with the biodistribution studies in five normal mice. The explanted organs from a patient who received a therapy dose of 18.6 mCi (688.2 MBq) Sn-117m(4+)DTPA and who died 47 days later were imaged with a gamma-camera, and tissue samples were counted and also autoradiographed. Bone, muscle, liver, fat, lungs, kidneys, spleen, heart and pancreas tissue samples were assayed in a well counter for radioactivity. Regions of interest were drawn over bone and major organs to calculate and quantify clearance times using three in vivo Sn-117m(4+)DTPA whole-body scintigrams acquired at 1, 24 and 168 h after injection. Five normal mice injected with the same batch of Sn-117m(4+)DTPA as used for the human subject were sacrificed at 24 h, and tissue samples were collected and assayed for radioactivity for comparison with the human data. For the human subject, whole-body retention at 47 days postinjection was 81% of the injected dose, and the rest (19%) was excreted in urine. Of the whole-body retained activity at 47 days, 82.4% was in bone, 7.8% in the muscle and 1.5% in the liver, and the rest was distributed among other tissues. Gamma-ray scintigrams and electron autoradiographs of coronal slices of the thoracolumbar vertebral body showed heterogeneous metastatic involvement with normal bone between metastatic lesions. There was nonuniform distribution of radioactivity even within a single vertebral body, indicating normal bone between metastatic lesions. Lesion-to-nonlesion ratios ranged from 3 to 5. However, the osteoid-to-marrow cavity deposition ratio, from the microautoradiographs, was 11:1. The peak uptake in the human bone was seen at 137 h with no biological clearance. Soft tissues showed peak uptake at 1 h and exhibited three compartmental clearance components. Whole-body retention in normal mice was 38.7% of the injected dose at 24 h and the rest was excreted. At 24 h postinjection, bone in mice showed 84.2% of the whole-body retention, muscle 1.7% and liver 1.4%, and the rest was distributed in other soft tissues. Percent distribution of the retained dose among bone, muscle, liver and other soft tissues is very similar between mice and a human subject. To calculate precise radiation absorbed doses from bone pain palliation radionuclides, it is necessary to take into account soft-tissue uptake and retention that may not be readily evident from routine external gamma-scintigraphy.
在一名接受转移性骨痛治疗的人类受试者中研究了Sn-117m(4+)DTPA的器官和组织摄取及滞留情况，并将结果与五只正常小鼠的生物分布研究进行了比较。对一名接受18.6 mCi（688.2 MBq）Sn-117m(4+)DTPA治疗剂量且47天后死亡的患者的离体器官用γ相机进行成像，对组织样本进行计数并进行放射自显影。在井型计数器中对骨、肌肉、肝脏、脂肪、肺、肾脏、脾脏、心脏和胰腺组织样本进行放射性测定。在骨和主要器官上绘制感兴趣区域，以使用注射后1、24和168小时获得的三张体内Sn-117m(4+)DTPA全身闪烁扫描图计算并量化清除时间。对五只注射了与人类受试者相同批次Sn-117m(4+)DTPA的正常小鼠在24小时时进行处死，收集组织样本并进行放射性测定以与人类数据进行比较。对于该人类受试者，注射后47天的全身滞留量为注射剂量的81%，其余（19%）经尿液排出。在47天时全身滞留的活性中，82.4%在骨中，7.8%在肌肉中，1.5%在肝脏中，其余分布在其他组织中。胸腰椎椎体冠状切片的γ射线闪烁扫描图和电子放射自显影片显示转移性病变呈异质性累及，转移性病变之间为正常骨。即使在单个椎体内放射性分布也不均匀，表明转移性病变之间为正常骨。病变与非病变的比值范围为3至5。然而，从显微放射自显影片来看，类骨质与骨髓腔的沉积比为11:1。人类骨中的最大摄取在137小时出现，无生物清除。软组织在1小时出现最大摄取，并呈现三个房室清除成分。正常小鼠在24小时时的全身滞留量为注射剂量的38.7%，其余经排出。注射后24小时，小鼠骨中的全身滞留量为84.2%，肌肉为1.7%，肝脏为1.4%，其余分布在其他软组织中。骨、肌肉、肝脏和其他软组织中滞留剂量的百分比分布在小鼠和人类受试者之间非常相似。为了精确计算缓解骨痛放射性核素的辐射吸收剂量，有必要考虑软组织的摄取和滞留情况，而这在常规外部γ闪烁扫描中可能不明显。
