PT - JOURNAL ARTICLE AU - Guardia, Miguel de la AU - Barnes, Jaime A. AU - Corey, Susan AU - Sims, Jennifer AU - Granger, Meaghan TI - Does Delayed Excretion of Therapeutic <sup>131</sup>I-MIBG Interfere with a <sup>123</sup>I-MIBG Diagnostic Scan 6 Weeks After the Therapy? AID - 10.2967/jnmt.119.229583 DP - 2020 Mar 01 TA - Journal of Nuclear Medicine Technology PG - 81--84 VI - 48 IP - 1 4099 - http://tech.snmjournals.org/content/48/1/81.short 4100 - http://tech.snmjournals.org/content/48/1/81.full SO - J. Nucl. Med. Technol.2020 Mar 01; 48 AB - 131I-metaiodobenzylguanidine (131I-MIBG) is a theranostic agent useful for treatment of neuroendocrine malignancies. In this case, a child with a Curie score of 21 was administered 17.871 GBq (483 mCi) of 131I-MIBG. The elimination half-life progressively increased from 23 h to 77 h during the 11 d that the patient was hospitalized for radiation isolation. Six weeks after the posttherapy scan, a survey with an ion-chamber device yielded readings of 0.3 μSv/h (0.03 mR/h) on contact with spinal regions that had shown increased uptake on the scan. A planar image obtained using the 131I setting and a high-energy collimator did not demonstrate any focal uptake. 123I-MIBG was administered, and the 24-h scan was of diagnostic quality, without degradation from the remaining 131I-MIBG. Additional study is needed on whether the Curie score affects elimination of 131I-MIBG and on whether the period of hospitalized radiation isolation needs to be extended.