Verburg F A, Verkooijen R B T, Stokkel M P M, van Isselt J W
Department of Nuclear Medicine, University Medical Center Utrecht.
Nuklearmedizin. 2009;48(4):138-42; quiz N19-20. doi: 10.3413/nukmed-0225. Epub 2009 Apr 22.
Dosimetry studies have shown that activities of 131I as small as 10-20 MBq may cause a stunning effect. A result of this stunning effect may be a lower success rate of the ablative 131I therapy for differentiated thyroid carcinoma (DTC). The aim of this study was to determine whether pre-therapeutic uptake measurement with 40 MBq 131I causes a lower success rate of ablation.
retrospective chart review study.
PATIENTS, METHODS: In two hospitals the ablation protocols differed in one respect only: in the one hospital no diagnostic 131I was applied before ablation (group 1, n = 48), whereas in the other hospital a 24-h uptake-measurement with 40 MBq 131I was performed (group 2, n = 51). Included were all DTC patients without distant metastases who had undergone 131I ablation between July 2002 and December 2005, and who had returned for 131I follow-up. Successful ablation was defined as absence of pathological 131I uptake on diagnostic whole-body scintigraphy and undetectable thyroglobulin-levels under TSH stimulation.
Overall, ablation was successful in 31/48 patients (65%) in group 1 and in 17/51 patients (33%) in group 2 (p=0.002). Multivariate analysis showed that pre-therapeutic uptake measurement using 40 MBq 131I was an independent determinant for success of ablation (p = 0.002).
After applying a diagnostic activity of 40 MBq 131I before ablation, the success rate of ablation is severely reduced. Consequently, the routine application of 131I for diagnostic scintigraphy or uptake measurement prior to 131I ablation is best avoided.
剂量学研究表明，低至10 - 20 MBq的131I活度可能会产生顿抑效应。这种顿抑效应的一个结果可能是分化型甲状腺癌（DTC）的131I消融治疗成功率降低。本研究的目的是确定使用40 MBq 131I进行治疗前摄取测量是否会导致消融成功率降低。
回顾性病历审查研究。
患者、方法：在两家医院，消融方案仅在一个方面有所不同：一家医院在消融前未应用诊断性131I（第1组，n = 48），而另一家医院使用40 MBq 131I进行了24小时摄取测量（第2组，n = 51）。纳入的是2002年7月至2005年12月期间接受131I消融且无远处转移并返回进行131I随访的所有DTC患者。成功消融定义为诊断性全身闪烁扫描时无病理性131I摄取且促甲状腺激素刺激下甲状腺球蛋白水平不可检测。
总体而言，第1组48例患者中有31例（65%）消融成功，第2组51例患者中有17例（33%）消融成功（p = 0.002）。多变量分析表明，使用40 MBq 131I进行治疗前摄取测量是消融成功的独立决定因素（p = 0.002）。
在消融前应用40 MBq 131I的诊断活度后，消融成功率会严重降低。因此，最好避免在131I消融之前常规应用131I进行诊断性闪烁扫描或摄取测量。
