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Radioactive iodine treatment is useful for ablating remnant thyroid tissue and metastasis of well-differentiated thyroid cancer with long-lasting effects. A scintigraphy after radioactive iodine treatment is a major imaging modality for detecting metastasis and assessing the management of metastasis. However, caution is required when reading the scan due to potential false-positive findings. In this study, scintigraphy and single-photon emission computed tomography/computed tomography images after radioactive iodine treatment revealed a physiological uptake of radioactive iodine due to lacrimal secretion around an artificial eyeball; such findings have not been reported previously.

PURPOSE: The aim of this study was to determine the influence of H2RAs to the 24-h I-131 uptake in the thyroid gland. MATERIAL AND METHODS: A prospective study with quasi-experimental pre- and post-study design was done. Subjects with normal fT4 level who fulfilled the inclusion criteria were selected. All subjects received 0.2 mCi of I-131 orally, and the thyroid uptake calculations were performed at 24 h later. The same procedure was performed 4 weeks later. All of the subjects were asked to consume H2RAs 1 h before the administration of I-131 of the second procedure. Both 24-h thyroid uptakes were statistically analysed. RESULTS: A total of 14 subjects were enrolled in this study. Most of them were women (78%) with an average age of 37.6 years old (range: 20–55). This study showed a median of 24-h thyroid uptake of I-131 before and after H2-receptor antagonist of 20.6% (range: 11.1–57.8%) and 16.7% (range: 8.1–39.4%) respectively. CONCLUSION: H2-receptor antagonist caused a significance reduction of 24-h I-131 uptake value in the thyroid gland.

Radioactive iodine (RAI) therapy for differentiated thyroid cancer has been successfully used for more than 70 years. However, there is still plenty of controversy surrounding the use and doses of radioiodine. There is insufficient evidence to answer the questions. Recent American Thyroid Association (ATA) guidelines seem to favor low-dose RAI, based on recent clinical trials and meta-analyses. However, long-term follow-up data remains limited, and there are additional factors we should consider that might affect the efficacy of RAI therapy. Therefore, until sufficient data are available, it is necessary to remain cautious about determining RAI doses by considering multiple patient-specific variables.

Single-photon emission computed tomography with integrated computed tomography (SPECT/CT) systems has been applied in a wide range of clinical circumstances, and differentiated thyroid cancer (DTC) is one of the most important indications of SPECT/CT imaging. In the treatment of DTC, SPECT/CT images have been reported to have many advantages over conventional planar whole-body scintigraphy based on its precise localization and characterization of abnormal foci of radioactive iodine (RAI) accumulation, influencing the staging, risk stratification, and clinical management as well as reader confidence. On the other hand, SPECT/CT has limitations including additional radiation exposure from the CT component, additional imaging time, and cost-related issues. Each SPECT/CT image acquired at different time points throughout the management of DTC may have a different clinical meaning and significance. This review article addresses the clinical usefulness of RAI SPECT/CT images acquired during the pre-ablation period, post-therapy period, and long-term follow-up period, respectively.

Nuclear medicine has been offering diagnostic and therapeutic solution since the introduction of radioactive iodine for thyroid diseases since decades. However, the concept of theranostics has given a new found impetus to the use of pairs of radiopharmaceuticals for diagnosis and treatment. Presented here is a perspective on theranostics from Pakistan.

We report a case of a 47-year-old female known with metastatic papillary thyroid cancer. Her treatment history included total thyroidectomy and 3 previous radio ablations with a cumulative dose of 950 mCi of (131)I. On follow-up, her thyroglobulin levels had demonstrated a rising trend (from 3789.0 to 4240.0 ug/L) despite a (123)I whole-body scan demonstrating a reduction in tracer avid lesions. She was suspected of having radio-resistant disease. The patient underwent both (18)F-FDG and (68)Ga-PSMA PET/CT imaging with both scans demonstrating congruent lesions however with far greater intensity on the (68)Ga-PSMA study.

To decrease the risk of recurrence or metastasis in differentiated thyroid cancer (DTC), selected patients receive radioactive iodine ablation of remnant thyroid tissue or tumor. A low iodine diet can enhance uptake of radioactive iodine. We compared the success rates of radioactive iodine ablation therapy in patients who followed two different low iodine diets (LIDs).The success rates of postsurgical radioactive iodine ablation in DTC patients receiving empiric doses of 150 mCi were retrospectively reviewed. First-time radioactive iodine ablation therapy was done in 71 patients following less strict LID and 90 patients following very strict LID. Less strict LID restricted seafood, iodized salt, egg yolk, dairy products, processed meat, instant prepared meals, and multi-vitamins. Very strict LID additionally restricted rice, freshwater fish, spinach, and soybean products. Radioactive iodine ablation therapy was considered successful when follow-up (123)I whole body scan was negative and stimulated serum thyroglobulin level was less than 2.0 ng/mL.The success rate of patients following less strict LID was 80.3% and for very strict LID 75.6%. There was no statistically significant difference in the success rates between the two LID groups (p = 0.48).Very strict LID may not contribute to improving the success rate of initial radioactive iodine ablation therapy at the cost of great inconvenience to the patient.

Salivary gland scintigraphy (SGS) provides an objective means of diagnosing salivary gland dysfunction in Sjögren's syndrome (SS) patients and in thyroid cancer patients after radioactive iodine (RAI) therapy. In the present study, SGS was performed in SS patients and in thyroid cancer patients post-RAI, and scintigraphic parameters were compared.Twenty-eight SS patients (males:females = 1:27, age 53.3 ± 11.9 years), 28 controls (males:females = 3:25, age 54.1 ± 10.1 years), and 92 thyroid cancer patients (males:females = 28:64, age 46.2 ± 12.9) who had undergone a session of high-dose RAI therapy (mean dose, 5.2 ± 1.5 GBq) were included. SGS was performed using Tc-99m pertechnetate (925 MBq). Scintigraphic parameters (parotid uptake ratio PU, submandibular uptake ratio SU, percentage parotid excretion %PE, and percentage submandibular excretion %SE) were measured and compared for SS, thyroid cancer post-RAI, and control patients.PU, SU, %SE, and %PE were all significantly lower in SS than in post-RAI thyroid cancer or control patients (p 0.05), whereas only %PE was significantly lower in post-RAI thyroid cancer patients than in controls (p 0.05). SU and %SE were found to be correlated with the unstimulated whole salivary flow rate.Scintigraphic parameters derived from SGS can play a crucial role in the detection of salivary gland dysfunction in SS patients and in post-RAI thyroid cancer patients.