The So-Called Stunning of Thyroid Tissue

Journal of Nuclear Medicine

Anca M. Avram¹  Paul G. Gauger¹  James C. Sisson¹  Susan A. Lawson¹  Gerard M. Doherty¹ 

关键词: stunning;    thyroid carcinoma;    radioiodine therapy;   

DOI  :  

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

When thyroid tissues exhibited concentrations of therapeutic 131I that appeared to be less than that predicted by data from the preceding diagnostic 131I, the phenomenon was called stunning. We hypothesized that stunning arose from the early effects of the therapeutic dose of 131I and that the initial uptake of 131I, observed within the first day, was not impaired by the diagnostic dose. Methods: The hypothesis was tested by 2 types of studies. In each type, the fractional concentrations of 131I in residual neck thyroid tissues of patients with papillary thyroid carcinoma were quantified. In the first study, fractional concentrations of diagnostic and therapeutic 131I were measured at 2 d, a time when stunning has been observed, and expressed as ratios of radioactivity: therapeutic/diagnostic (Rx/Dx). Three different doses of diagnostic 131I were prescribed to assess a dose response. In the second study, patients were prospectively recruited and tested to record disappearances of radioactivity from thyroid tissues. Diagnostic doses were 1.0 mCi (37 MBq) in all; therapeutic doses were 150 and 30 mCi (5,550 and 1,110 MBq), each to half of the patients. The disappearance curves were extrapolated to the period between 0 and 1 d, an interval when maximum uptake of ingested 131I would be expected. The fractional concentrations of 131I at 2 d and at 0–1 d were compared in terms of Rx/Dx ratios to assess changes at each time point. Results: In the first study, after diagnostic doses of 2, 1, and 0.5 mCi (74, 37, and 18.5 MBq), mean 2-d Rx/Dx values in 24, 29, and 17 patients were 0.35, 0.50, and 0.46 (P = 0.087). Of all patients, 74% exhibited Rx/Dx <0.6. In the second study, 6 of 10 patients exhibited disappearance curves of 131I in which Rx/Dx was <0.6 at 2 d; 5 of the 6 had Rx/Dx values >0.97 at the 0- to 1-d point. In 1 patient the Rx/Dx was 0.54 at 2 d and 0.66 at the earlier time point. The other 4 patients had disappearance curves in which Rx/Dx values were >1.0 throughout or were above 0.6 and did not greatly change. Conclusion: Two days after the administration of 131I, the mean fractional concentration of radioactivity in thyroid tissues after a therapeutic dose is <60% of the diagnostic dose in most patients, but no correlation of Rx/Dx with the mCi in the diagnostic dose was seen. In 5 of 6 patients in whom the Rx/Dx at 2 d was <0.6, the maximum fractional concentrations of therapeutic and diagnostic 131I (i.e., the tissue uptakes during the first day) were similar; this pattern was most apparent after therapies with 150 mCi. These results support the hypothesis that “stunning” of thyroid tissues, often observable by 2 d, is primarily the consequence of early destructive effects from therapeutic 131I.

【 授权许可】

Unknown