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

Burlison JS, Hartshorne MF, Voda AM, Cocks FH, Fair JR - Nucl Med Commun (2013)

Bottom Line: 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.Furthermore, in-vitro studies demonstrate partially reversible binding of 131I to common dental metals.

View Article: PubMed Central - PubMed

Affiliation: aDepartment of Radiology, University of New Mexico bPrivate Practice, Albuquerque, New Mexico cDepartment of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina, USA.

ABSTRACT

Purpose: 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.

Results: 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.

Conclusion: 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.

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Related in: MedlinePlus

Percentage of initial radioiodine retained in dental amalgam samples after multiple normal saline (NS) washes, with non-zero asymptotes indicating residual iodine-131 (131I) binding. Washes were continued until the change in radioiodine activity remaining after the final wash was less than background activity. This washing procedure was performed for all dental metal samples, both after the 131I/NS incubation and after the saturated solution of potassium iodide soak.
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Figure 4: Percentage of initial radioiodine retained in dental amalgam samples after multiple normal saline (NS) washes, with non-zero asymptotes indicating residual iodine-131 (131I) binding. Washes were continued until the change in radioiodine activity remaining after the final wash was less than background activity. This washing procedure was performed for all dental metal samples, both after the 131I/NS incubation and after the saturated solution of potassium iodide soak.

Mentions: For a proof-of-principle assessment of radioiodine binding to dental metals, we performed in-vitro binding assays with samples of dental amalgam and Argenco HP 77 incubated with an 131I/NS solution for varying time periods, followed by multiple washings (Fig. 4). After washings, typical 131I activities ranged from 5×106 to 5×104 cpm, whereas the daily measured background was 150–180 cpm


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

Burlison JS, Hartshorne MF, Voda AM, Cocks FH, Fair JR - Nucl Med Commun (2013)

Percentage of initial radioiodine retained in dental amalgam samples after multiple normal saline (NS) washes, with non-zero asymptotes indicating residual iodine-131 (131I) binding. Washes were continued until the change in radioiodine activity remaining after the final wash was less than background activity. This washing procedure was performed for all dental metal samples, both after the 131I/NS incubation and after the saturated solution of potassium iodide soak.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3815121&req=5

Figure 4: Percentage of initial radioiodine retained in dental amalgam samples after multiple normal saline (NS) washes, with non-zero asymptotes indicating residual iodine-131 (131I) binding. Washes were continued until the change in radioiodine activity remaining after the final wash was less than background activity. This washing procedure was performed for all dental metal samples, both after the 131I/NS incubation and after the saturated solution of potassium iodide soak.
Mentions: For a proof-of-principle assessment of radioiodine binding to dental metals, we performed in-vitro binding assays with samples of dental amalgam and Argenco HP 77 incubated with an 131I/NS solution for varying time periods, followed by multiple washings (Fig. 4). After washings, typical 131I activities ranged from 5×106 to 5×104 cpm, whereas the daily measured background was 150–180 cpm

Bottom Line: 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.Furthermore, in-vitro studies demonstrate partially reversible binding of 131I to common dental metals.

View Article: PubMed Central - PubMed

Affiliation: aDepartment of Radiology, University of New Mexico bPrivate Practice, Albuquerque, New Mexico cDepartment of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina, USA.

ABSTRACT

Purpose: 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.

Results: 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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus