SPECT/CT Characterization of Oral Activity on Radioiodine Scintigraphy

Savas, Hatice; Wong, Ka Kit; Saglik, Berna; Hubers, David; Ackermann, Robert; Avram, Anca M.

doi:10.1210/jc.2013-2467

Cited by 8 publications

(5 citation statements)

References 28 publications

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“…Another commonly seen finding on radioiodine scintigrams is radiotracer activity in the region of the oral cavity, corresponding to tracer retention in dental amalgam (Fig 12). A proposed mechanism is retention of radioiodine because of the interaction of negatively charged iodide ions with positively charged metal ions within dental restoration materials (48). Other causes of radioiodine retention are listed in the Table.…”

Section: Radioiodine Retentionmentioning

confidence: 99%

Pictorial Review of False-Positive Results on Radioiodine Scintigrams of Patients with Differentiated Thyroid Cancer

Chudgar¹,

Shah²

2017

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Radioiodine has served an important role in the diagnostic workup and treatment of patients with differentiated thyroid cancer for more than 6 decades. The interpretation of radioiodine scintigraphic studies should be performed in conjunction with a comprehensive history, histopathologic correlation, and pertinent laboratory values, as well as correlation with available anatomic images and the findings from physical examination. A thorough understanding of the physiology and biodistribution of radioiodine is critical when interpreting radioiodine scintigraphic studies to avoid misinterpretation of physiologic and nonthyroid pathologic variants as thyroid cancer metastases. Differentiating a false-positive finding from a true metastasis on pretherapy radioiodine scintigrams is important to determine the appropriate radioiodine treatment dose. The correct interpretation of posttherapy radioiodine scintigraphic studies is also important to determine if repeat radioiodine treatment will be necessary and for the future clinical and imaging followup of the patient. A variety of different factors, such as the presence of the sodium-iodide symporter and the passive diffusion or retention of radioiodine in normal and pathologic structures, can result in false-positive results on radioiodine scintigrams. Numerous false-positive findings have been reported in the literature and are further demonstrated with the increasing availability of single photon emission computed tomography (SPECT) integrated with computed tomography (CT) as true dual-modality imaging (SPECT/CT). SPECT/CT has been documented to be of incremental value in the accurate anatomic localization and characterization of radioiodine uptake as false-positive findings, particularly in cases with discordant findings of a low serum thyroglobulin level but positive findings on radioiodine whole-body planar scintigrams. The objectives of this review are to describe the physiology and biodistribution of radioiodine and to provide examples of false-positive results on radioiodine scintigrams, with clinical and anatomic correlation, in the following categories of radioiodine uptake: functional uptake secondary to sodium-iodide symporter expression, radioiodine retention, nonthyroid neoplasms, inflammatory or infectious uptake, contamination, and other causes. RSNA, 2017.

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Section: Radioiodine Retentionmentioning

confidence: 99%

Pictorial Review of False-Positive Results on Radioiodine Scintigrams of Patients with Differentiated Thyroid Cancer

Chudgar¹,

Shah²

2017

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“…One of the most commonly seen materials with this behavior is dental amalgam (Fig. 5a) [80,81]. The proposed mechanism of tracer retention demonstrated by in-vitro binding assays is the interaction and chemical binding of negatively charged iodide ions to the positively charged metal ions [80,81].…”

Section: Direct Rai Bonding To Metallic Foreign Bodiesmentioning

confidence: 99%

Causes of False-Positive Radioactive Iodine Uptake in Patients with Differentiated Thyroid Cancer

Ozomaro

Flavell

et al. 2021

Curr Radiol Rep

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Purpose Radioactive iodine (RAI) whole-body scan is a sensitive imaging modality routinely used in patients with differentiated thyroid cancer to detect persistent and recurrent disease. However, there can be false-positive RAI uptake that can lead to misdiagnosis and misclassification of a patient’s cancer stage. Recognizing the causes of false positivity can avoid unnecessary testing and treatment as well as emotional stress. In this review, we discuss causes and summarize various mechanisms for false-positive uptake. Recent Findings We report a patient with differentiated thyroid cancer who was found to have Mycobacterium avium complex infection as the cause of false-positive RAI uptake in the lungs. Using this case example, we discuss and summarize findings from the literature on etiologies of false-positive RAI uptake. We also supplement additional original images illustrating other examples of false RAI uptake. Summary False-positive RAI uptake may arise from different causes and RAI scans need to be interpreted in the context of the patient’s history and corresponding cross-sectional imaging findings on workup. Understanding the potential pitfalls of the RAI scan and the mechanisms underlying false uptake are vital in the care of patients with differentiated thyroid cancer.

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“…Two papers independently reported the utility of SPET-CT for investigation of a physiological mechanism of radioiodine uptake not previously described in the literature. Savas and colleagues reviewed 216 SPET-CT scans and found that oral radioiodine uptake was present on 123 (57 %) [79] and postulated an affinity of radioiodine for metals via a semi-permanent chemical reaction. Others studied 58 post-therapy patients with SPET-CT and confirmed that 91 % showed focal radioiodine localizing to dental restorations [80].…”

Section: Spet-ct Diagnostic Interpretationmentioning

confidence: 99%

SPET–CT in thyroid cancer: a systematic review

Wong

Wale

Fig

et al. 2014

Clin Transl Imaging

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The purpose of this study was to systematically review the utility of single-photon emission tomographycomputed tomography (SPET-CT) fusion imaging in the investigation of thyroid cancer. We performed a systematic search of the world literature on radionuclide SPET-CT imaging of thyroid cancer using the medical databases Medline (OVID) and PubMed. The following search terms were used to identify relevant studies: (a) thyroid, combined with (b) SPECT/CT or SPECT-CT or SPET/CT or SPET-CT. The electronic searches returned citations for 1,189 potentially eligible articles and 98 abstracts were reviewed for relevance by two co-authors. Thirty-one peerreviewed full articles reporting the utility, value and diagnostic performance of radioiodine SPET-CT for the imaging of well-differentiated thyroid cancer were selected. The quality of these studies was assessed using the quality assessment of diagnostic accuracy studies-2 tool.As there was heterogeneity in the studies, a systematic review analysis was conducted as our chosen research synthesis method. A total of 31 studies published between 2003 and 2014 report the utility of radioiodine SPET-CT. These studies uniformly found incremental diagnostic value of I-123 and I-131 SPET-CT over SPET and/or planar imaging. SPET-CT allows accurate characterization of radioiodine uptake in the neck and at distant sites, clarifies equivocal foci of radioactivity, improves specificity for disease, and evaluates benign physiological etiologies. Additional pilot uses of SPET-CT have been reported, e.g., for thyroid nodule evaluation, medullary thyroid cancer work-up, and investigation of lingual thyroid. Radioiodine SPET-CT fusion imaging of thyroid cancer has incremental utility, improving image interpretation as compared to planar and SPET imaging. It is likely to see more widespread application in the future.

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SPECT/CT Characterization of Oral Activity on Radioiodine Scintigraphy

Cited by 8 publications

References 28 publications

Pictorial Review of False-Positive Results on Radioiodine Scintigrams of Patients with Differentiated Thyroid Cancer

Pictorial Review of False-Positive Results on Radioiodine Scintigrams of Patients with Differentiated Thyroid Cancer

Causes of False-Positive Radioactive Iodine Uptake in Patients with Differentiated Thyroid Cancer

SPET–CT in thyroid cancer: a systematic review

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