Abstract:
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Purpose: In the thyroid treatment of radioiodine, it is one of the important factors to improve radioiodine accumulation in thyroid gland. In this study, we aimed to increase thyroid accumulation of radioiodine, keeping blood concentration by competitive inhibition of renal excretion.
Methods and Materials: The rats without anesthetization received 123I-NaI (370 kBq) in saline via the tail vein as control condition. After the injection, dynamic imaging until 60 minutes and static imaging 3 hours and 24 hours after 123I injection were constructed by a scintillation camera (Picher Prism 3000). While, assuming oral administration in clinical application, continuous injection of probenecid, an inhibitor of the organic anion transporter, was performed. After attenuation of the radioactivity in the body, probenecid (100 mg/kg body weight/day) was loaded to the same rat via the femoral vein using the syringe pump from 1 hour before the tracer injection to 24 hours after that. Under this condition, the imaging was performed according to the same methods as the control.
Results: With probenecid loading, the accumulation in the thyroid gland was increased 1.3-1.4 times compared with the control condition within 60 minutes after the tracer injection, and more than 1.3 times of accumulation was revealed at any times until 24 hours. At 3 hours, in particular, remarkable improvement of thyroid accumulation was noted, it was raised 1.8-2.3 times higher than the control. Therefore, during the imaging time, improvement in radioiodine accumulation with probenecid loading was evaluated. Meanwhile, the uptake in the stomach was almost the same within 60 minutes and then significantly decreased (0.2-0.9 times) compared with the control condition.
Conclusion: It was shown that maintaining of blood concentration by competitive inhibition of renal excretive transporter increased radioiodine accumulation in the thyroid gland with the sodium iodide symporter. This convenient method is promising to allow more effective radioiodide treatment in such as Gravesą disease and the management of thyroid carcinoma after thyroidectomy.
Kobayashi, M,
Competitive Inhibition of Renal Excretion: Application to Increase Thyroid Accumulation of Radioiodine for Iodine-131 Therapy. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3108565.html
