SPECT/CT localization of oral radioiodine activity: a retrospective study and in-vitro assessment.

Journal Article (Journal Article)


We sought to further localize radioiodine activity in the mouth on post-thyroid cancer therapy imaging using single-photon emission computed tomography/computed tomography (SPECT/CT).

Materials and methods

We retrospectively reviewed all patients (58) who underwent thyroid cancer therapy with iodine-131 (131I) at our institution from August 2009 to March 2011 whose post-therapy radioiodine imaging included neck SPECT/CT. A small group (six) of diagnostic 131I scans including SPECT/CT was also reviewed. Separately, we performed in-vitro 131I (sodium iodide) binding assays with amalgam and Argenco HP 77 (77% dental gold alloy) as proof of principle for these interactions.


Of the 58 post-therapy patients, 45 (78%) had undergone metallic dental restorations, and of them 41 (91%) demonstrated oral 131I activity localizing preferentially to those restorations. It was observed that radioiodine also localized to other dental restorations and to orthodontic hardware. Gum-line activity in edentulous patients suggests radioiodine interaction with denture adhesive. In vitro, dental amalgam and Argenco HP 77 bound 131I in a time-dependent manner over 1-16 days of exposure. Despite subsequent washings with normal saline, significant 131I activity (maximally 12% for amalgam and 68% for Argenco HP 77) was retained by these metals. Subsequent soaking in a saturated solution of potassium iodide partially displaced 131I from amalgam, with near-total displacement of I from Argenco HP 77.


SPECT/CT shows that radioiodine in the oral cavity localizes to metallic dental restorations. Furthermore, in-vitro studies demonstrate partially reversible binding of 131I to common dental metals.

Full Text

Duke Authors

Cited Authors

  • Burlison, JS; Hartshorne, MF; Voda, AM; Cocks, FH; Fair, JR

Published Date

  • December 2013

Published In

Volume / Issue

  • 34 / 12

Start / End Page

  • 1216 - 1222

PubMed ID

  • 24128897

Pubmed Central ID

  • PMC3815121

Electronic International Standard Serial Number (EISSN)

  • 1473-5628

International Standard Serial Number (ISSN)

  • 0143-3636

Digital Object Identifier (DOI)

  • 10.1097/mnm.0000000000000004


  • eng