title: A Clinical Trial of Optimal Time Interval Between Ablation and Diagnostic Activity When a Pretherapy RAI Scanning Is Performed on Patients With Differentiated Thyroid Carcinoma.
abstract: This article investigates the association of the time interval between the diagnostic dose and ablation with the stunning effect, when a 74 MBq I pretherapy scanning was performed on patients with differentiated thyroid carcinoma (DTC); the patients who were diagnosed as DTC and would be performed radioiodine (RAI) ablation of thyroid remnants or metastases were recruited during January 2011 and May 2012 in our hospital.Thirty-seven patients with DTC who had the RAI ablation of thyroid remnants or metastases for the first time were recruited. All the patients received a dose of 1850 to 7400 MBq of I for ablation and a diagnostic scan was performed 24 hours after the administration of 74 MBq I before ablation. A posttherapy scan was performed 2 to 7 days after the ablation. The patients were broken down into 3 groups (G1, G2, and G3) according to the interval time between the diagnostic dose and therapy (1-3, 4-7, and >7 days). The fractional concentrations of I in remnants or functional metastases were quantified and expressed as therapeutic/diagnostic (Rx/Dx). The level of significance was set at 0.05.Sixty-seven foci were found both on pretherapy and posttherapy scans, the mean ratio of Rx/Dx was 0.43 ± 0.29, and the ratio of 49 foci (73.13%) was <0.6. The ratios in G1, G2, and G3 were 0.46 ± 0.29, 0.29 ± 0.18, and 0.55 ± 0.33, respectively. The differences between G1 and G2, and G2 and G3 were statistically significant (t = 2.40, P = 0.021 and t = 3.28, P = 0.002), whereas the difference between G1 and G3 was not significant (t = 1.01, P = 0.319).By a diagnostic scan of 74 MBq I, stunning prominently occurs with a time of 4 to 7 days between the diagnostic dose and ablation. We recommend that for less stunning effect, RAI ablation should be performed within 3 days or postponed until 1 week after the diagnostic dose administrated.
authors.affiliation: From the Department of Nuclear Medicine, The First Hospital of China Medical University, China Medical University, Shenyang, China.
authors.forename: Yafu
authors.initials: Y
authors.lastname: Yin
authors.forename: Qiufen
authors.initials: Q
authors.lastname: Mao
authors.forename: Song
authors.initials: S
authors.lastname: Chen
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Xuena
authors.initials: X
authors.lastname: Li
authors.forename: Yaming
authors.initials: Y
authors.lastname: Li
mesh_terms: D055011:Ablation Techniques; D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D013965:Thyroidectomy; D013997:Time Factors; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals