Bhishak H. Kamat MD, Presenter: Nothing to Disclose

Vincent Q. Dam MD, Abstract Co-Author: Nothing to Disclose

Susan Elizabeth Mandel MD, Abstract Co-Author: Nothing to Disclose

Daniel Pryma MD, Abstract Co-Author: Research Grant, Siemens AG Research Grant, Molecular Insight Pharmaceuticals, Inc Speaker, IBA Molecular Advisory Board, Bayer AG

Michael David Farwell MD, MA, Abstract Co-Author: Nothing to Disclose

Current thyroid scintigraphy guidelines recommend waiting 1-2 months after administration of intravenous iodinated contrast for accurate uptake measurements. However, the utility of thyroid scintigraphy for evaluating thyrotoxicosis in the setting of recent intravenous contrast/iodine load is not known. The purpose of this retrospective study was to determine whether recent iodine administration affects the imaging and interpretation of Tc-99m pertechnetate thyroid scintigraphy.

The records of all patients who underwent Tc-99m pertechnetate scintigraphy between March 2007 and March 2014 were reviewed. Patients with low or undetectable TSH who received intravenous iodinated contrast or SSKI within one week prior to imaging were selected, and their pertechnetate scans were reviewed along with clinical and laboratory data.

50 patients were screened and 15 were identified who had undergone Tc-99m pertechnetate scintigraphy within one week after receiving intravenous contrast or SSKI. Thyroid scans with uptake greater than the submandibular glands were interpreted as Grave’s disease (11/15) or toxic nodular goiter (1/15), which was consistent with clinical and laboratory follow-up; of note, 2 of these patients received intravenous contrast or SSKI within twenty-four hours of imaging and 5 more within 48 hours prior to imaging. Thyroid scans with no uptake (2/15) or uptake less than submandibular glands (1/15) were interpreted as thyroiditis, which was consistent with clinical and laboratory follow-up.

Tc-99m pertechnetate thyroid scintigraphy appears to be a useful diagnostic test for differentiating Grave’s disease or toxic nodular goiter from thyroiditis in hyperthyroid patients who have recently received iodine/intravenous iodinated contrast.

Tc-99m pertechnetate thyroid imaging should be considered in the evaluation of thyrotoxicosis in patients with a recent iodine load.

Kamat, B, Dam, V, Mandel, S, Pryma, D, Farwell, M, Utility of Tc-99m Pertechnetate Thyroid Scintigraphy in Hyperthyroid Patients with Recent Exposure to Iodine/Intravenous Iodinated Contrast.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007407.html