Baker R J
Department of Nuclear Medicine, Prince of Wales Hospital, Randwick, NSW 2031, Australia.
Nucl Med Commun. 2002 Feb;23(2):139-45. doi: 10.1097/00006231-200202000-00005.
It has been reported that administration of the paramagnetic contrast agent Gd-diethylenetriaminepentaacetic acid (Gd-DTPA, gadopentate) prior to 67Ga citrate could lead to poor quality scans, characterized by pronounced bone uptake and a loss of tumour avidity. Suggestions to account for this behaviour included in vivo dissociation or the presence of free DTPA in the formulation. The objective of this study was to assess this potential interference in 67Ga imaging using a mouse model. Commercial gadopentate and gadodiamide contrast agents at doses up to 5mmolkg(-1) were injected into mature female Balb/c mice 4h before i.v. 67Ga citrate, then the biodistribution was determined at 24h. Gd-DTPA solutions containing excess Gd or DTPA were examined as well. The model was verified by identical studies using inactive Ga(III) or Fe(III) at 0.1mmolkg(-1). The effects of Gd(III) or the DTPA ligand at this dose were also determined. Administration of Gd-DTPA was found to produce no marked changes in 67Ga biodistribution. Minor changes occurred after 0.1mmol*kg(-1) Gd(III) or the DTPA ligand, but could not account for the scan changes reported above. Inactive Ga(III) or Fe(III), as expected, caused a marked reduction of 67Ga uptake in all tissues except bone, leading to greatly increased total bone:total soft tissue ratios. It is concluded that Gd-DTPA or its constituents do not significantly alter the biodistribution of 67Ga citrate in mice. Extrapolating these findings to the human situation suggests that the previously reported scan changes may have been the result of other undetermined factors.
据报道，在注射柠檬酸镓（67Ga）之前给予顺磁性造影剂钆喷酸葡胺（Gd - 二乙烯三胺五乙酸，Gd - DTPA，钆双胺）可能会导致扫描质量不佳，其特征为骨骼摄取明显增加以及肿瘤亲和力丧失。对这种现象的解释包括体内解离或制剂中存在游离的二乙烯三胺五乙酸（DTPA）。本研究的目的是使用小鼠模型评估这种对67Ga成像的潜在干扰。在静脉注射柠檬酸镓前4小时，将剂量高达5mmol·kg-1的市售钆双胺和钆贝葡胺造影剂注入成年雌性Balb/c小鼠体内，然后在24小时时测定生物分布。还检测了含有过量钆或二乙烯三胺五乙酸的钆喷酸葡胺溶液。使用0.1mmol·kg-1的无活性镓（III）或铁（III）进行相同的研究来验证该模型。还确定了该剂量下钆（III）或二乙烯三胺五乙酸配体的作用。发现给予钆喷酸葡胺不会使67Ga的生物分布产生明显变化。给予0.1mmol·kg-1的钆（III）或二乙烯三胺五乙酸配体后发生了微小变化，但无法解释上述扫描变化。如预期的那样，无活性的镓（III）或铁（III）导致除骨骼外的所有组织中67Ga摄取明显减少，从而导致骨与软组织的总比值大大增加。结论是，钆喷酸葡胺或其成分不会显著改变柠檬酸镓在小鼠体内的生物分布。将这些发现外推至人体情况表明，先前报道的扫描变化可能是其他未确定因素导致的结果。
