Dose Of Radioiodine Research Articles

Comparison of Thyroid Size-Specific Radioiodine Dose and New Modified Dose Calculation in the Treatment of Graves' Disease.

Previous studies of fixed-dose radioiodine therapy (RIT) for Graves' disease (GD) have utilized a variety of techniques and reported differing success rates. This study sought to compare the efficacy of RIT using two fixed-dose protocols and to estimate the optimal radioiodine (RAI) activity for the treatment of GD. This retrospective trial enrolled 658 patients with GD who received RIT between January 2014 and December 2021. Participants were divided into two groups: protocol 1, which utilized a thyroid size-specific RAI dose, and protocol 2, which employed a modified dose calculation approach. The primary outcome assessed was the presence of euthyroidism or hypothyroidism at the 6-month follow-up. The success rates of RIT were compared between the two protocols. The RIT success rate was marginally lower for protocol 2 than for protocol 1 (63.6% vs. 67.2%); however, the risk of treatment failure did not differ considerably between the groups (relative risk, 1.1089; 95% confidence interval, 0.8937 to 1.3758; P=0.3477). The median RAI activity associated with protocol 2 was lower than that for protocol 1 (10.7 mCi vs. 15.0 mCi, P=0.0079), and the frequency of hypothyroidism was significantly lower in the protocol 2 group (39.0% vs. 48.9%, P=0.0117). The success rate of the modified dose calculation protocol was comparable to that of the thyroid size-specific RAI dose protocol. The former approach reduced RAI activity and the incidence of hypothyroidism following RIT without compromising the success rate.

7179 Efficacy of radioactive iodine for the treatment of thyrotoxicosis in a prospective cohort in Aotearoa/New Zealand

Abstract Disclosure: J. Tamatea: None. S. Nottingham: None. V. Boyle: None. M.S. Elston: None. Background – The outcome following treatment of thyrotoxicosis with a single fixed-dose radioiodine (RAI) can be difficult to predict and has been shown to have a lower success rate in Māori vs. non-Māori (1).Aim – the aim of this prospective study was to compare RAI treatment outcomes between Māori and non-Māori, identify factors that are associated with RAI treatment failure in thyrotoxicosis and whether these factors affect the difference in ethnicity outcomes seen.Method – all patients over the age of 16 years referred to Waikato Hospital (Hamilton, New Zealand) for the treatment of thyrotoxicosis with RAI between March 2013 and February 2015 were invited to participate in this study. Demographic information was collected with a questionnaire prior to treatment. Aetiology and severity of thyrotoxicosis at time of diagnosis was retrospectively collected. Laboratory investigations, ultrasound thyroid volume and thyroid pertechnetate uptake were carried out prior to RAI treatment. Participants were followed up for12 months after RAI to assess outcome to treatment. Univariate analysis of variables were carried out for the full cohort and for Graves’ Disease (GD) cohort. Logistic regression analysis was carried out including ethnicity and additional variables of age, gender, diagnosis, thyroid volume, smoking status, and BMI.Results – a total of 162 participants were included: 71 identified as Māori and 91 as non-Māori. At 12 months follow up, 146 participants (90.1%) had a successful treatment outcome follow a single dose of RAI. Successful outcome was achieved in 85.9% of Māori vs 93.4% of non-Māori (p = .113), however when only looking at the GD cohort, Māori were less likely to have successful outcome than non-Māori (68.75% vs 89.4% p = .022). Following regression analysis ethnicity was no longer a variable associated with treatment failure. When controlling for other variables, factors found to increase the risk of failing RAI were diagnosis of TMNG/STA (OR 0.03; 95%CI 0.002-0.035), larger thyroid volumes (OR 1.04; 95%CI 1.01 - 1.07 per mL of thyroid volume) and smoking (OR 6.71; 95%CI 1.2 - 37.4 for current smokers).Conclusion - RAI is an effective definitive treatment option for thyrotoxicosis. Factors found to be associated with treatment outcome are aetiology of thyrotoxicosis, thyroid volume, and smoking status. These factors likely explain the ethnicity difference in treatment outcome following RAI in Māori vs non-Māori.References – 1. Tamatea JAU, Conaglen JV, Elston MS. Response to Radioiodine Therapy for Thyrotoxicosis: Disparate Outcomes for an Indigenous Population. International Journal of Endocrinology. 2016;2016:7863867. Presentation: 6/2/2024

Comparison of Thyroid Uptake Values Measured from 131I Scintigraphy and Uptake Probe in Hyperthyroid Patients

Objective: Thyroid uptake test plays an important role in diagnosis, treatment planning and radioiodine dose determination in patients with hyperthyroidism. The aim of this study was to compare the % uptake values calculated with gamma camera and uptake probe after diagnostic 131I application in hyperthyroid patients. Materials and Methods: In this study, % uptake values were measured using a thyroid uptake probe and gamma camera in 32 patients who underwent thyroid radioiodine uptake measurement in our Nuclear Medicine center. Thyroid uptake measurements were prepared in the neck phantom with 0.74–0.925 MBq activity of 131I radionuclide. After counting the phantom with 131I separately in the uptake probe and gamma camera, 131I sample was orally administered to the patient. % uptake values were calculated by the uptake probe measurements and drawing regions of interest (ROI) from scintigraphic images at 2 and 24 h. Results: The 2-h mean % uptake values in the probe and gamma camera were calculated as 30.5 ± 20.4 and 27.1 ± 18.6, respectively. The 24-h mean % uptake values in the thyroid probe and gamma camera were calculated as 57.6 ± 21.9 and 55.3 ± 21.5, respectively. Linear regression analyses for the 2- and 24-h % uptake values calculated with the probe and gamma camera were found as R2 = 0.8412 and R2 = 0.7313, respectively. Conclusion: The 2- and 24-h % uptake values with the probe and gamma camera were found to be consistent with each other, indicating that they can be safely used interchangeably in patients with hyperthyroidism.

Association of Free Thyroxine with Progression-Free Survival in Intermediate and High Risk Differentiated Thyroid Cancer.

Supraphysiologic thyroxine (T4) doses are used in intermediate and high-risk patients with differentiated thyroid cancer (IR/HR-DTC) to suppress tumor progression by thyrotropin (TSH). However, preclinical data suggest that T4 can also act as a growth stimulus for cancer, but there is no clinical evidence supporting this claim. We analyzed the association between free T4 (FT4) and progression-free survival (PFS) in patients with IR/HR-DTC. This longitudinal cohort study, approved by multi-institutional review board, included patients with IR/HR-DTC treated uniformly with total thyroidectomy, radioiodine (RAI), and TSH suppression therapy, with at least three TSH and FT4 values available. Association between FT4 and PFS at landmarks 6, 12, and 18 months was assessed by Kaplan-Meier survival curves, while competing risks were assessed through Cox proportional hazards model. From 739 screened patients 382 met the inclusion criteria and were characterized by a median age of 46 (34-59) years, 64.1% women, treated with a median RAI dosage of 159 (110-410) mCi. During follow up of 7.1 (3.4-12.7) years 34.6% experienced disease progression.Elevated FT4, observed in 29.3% of patients, was not associated with worse PFS (HR 0.9, CI 0.54-1.5, p=0.69), while age (HR 1.02, CI 1.004-1.04, p=0.01), tumor size (HR 1.15, CI 1.04-1.28, p=0.01), and metastases to the lateral neck lymph nodes (HR 2.9, CI 1.7-4.74, p<0.001), bones (HR 4.87, CI 1.79-13.3, p=0.002), and brain (HR 5.56, CI 2.54-12.2, p<0.001) were associated with shorter PFS. Contrary to preclinical evidence, elevated FT4 levels do not affect PFS in patients with IR/HR-DTC.

Evolution in the management of thyroid surgery over a period of 15 years in a Belgian center

BackgroundGuidelines for thyroid surgery have evolved to reflect advances in medical knowledge and decrease the overdiagnosis of low-risk thyroid cancer. Our goal was to analyze the change made in operative thyroid management and the impact on thyroid cancer diagnosis.BackgroundGuidelines for thyroid surgery have evolved to reflect advances in medical knowledge and decrease overdiagnosis of low risk thyroid cancer. Our goal was to study the evolution, over a long period, of pre- and postoperative management and the influence on histological cancer diagnosis and, more particularly, microcancer.MethodsIn this retrospective cohort study, we included 891 consecutive patients who underwent thyroid surgery between 2007 and 2020.ResultsRespectively 305, 290 and 266 patients underwent surgery over the 3 periods of 2007–2010, 2011–2015 and 2016–2020. In all three periods, women represented approximately 70% of the population, and the mean age was 54 years old (range: 67). Most surgeries (90%) involved total thyroidectomies. Over the study period, the proportion of preoperative fine needle aspiration (FNA) increased from 13 to 55%, p < 0,01. Cancer was found in a total of 116 patients: 35 (11%) patients between 2007 and 2010, 50 (17%) between 2011 and 2015 and 32 (12%) between 2016 and 2020 (p = 0.08). For all 3 periods, papillary thyroid cancer (PTC) was the most prevalent, at approximately 80%. The proportion of thyroid cancer > T1a increased significantly from 37% (2011–2015 period) to 81% (2016–2020 period), p = 0.001. Patients treated with radioiodine remained relatively stable (approximately 60%) but were more frequently treated with a low dose of radioiodine (p < 0.01) and recombinant human TSH (p < 0.01). Operative thyroid weight decreased over time in all but the low-risk T1a PTC cases.ConclusionsOver a period of 15 years and according to the evolution of recommendations, the care of patients who underwent thyroid surgery changed with the increased use of preoperative FNA. This change came with a decrease in low-risk T1a PTC.

Potential clinical application of anti-Müllerian hormone testing in radioiodine treatment of thyroid carcinoma

Differentiated thyroid cancer is the most common endocrinological malignancy. Radioiodine treatment has a clear benefit in locally aggressive and metastatic cancers. There are discussions about long-term and acute adverse events.Anti-Müllerian hormone is regarded as the best endocrine marker for evaluating the physiological loss of oocytes in healthy women with regard to age. The impact of radioiodine treatment on anti-Müllerian hormone levels has been more significantly reported in patients over 35 years of age. About reproductive dysfunction, calculations of individual absorbed doses of radioiodine in ovaries after thyroid cancer therapy have not been performed yet. The aim of our ongoing prospective study is to determine serum anti-Müllerian hormone to estimate ovarian reserve for premenopausal women treated with radioiodine and to compare anti-Müllerian hormone levels before and after radioiodine treatment. Predicting radioiodine side effects by evaluating a simple serum biomarker may help to select an appropriate treatment strategy for young women planning pregnancy, specifically in the assessment of ovarian reserve and premature ovarian failure with early onset of menopause.

Long-Term Follow-up of Patients With Autonomous Thyroid Nodules Treated With Radioiodine.

This article aims to describe the presentation of Plummer disease and its evolution after radioiodine treatment and determine factors that may influence treatment efficacy. The sample included retrospective medical records of 165 adult patients with toxic nodular goiter treated with radioiodine between 1997 and 2017, followed up at a single thyroid center. The efficacy of treatment with a single dose of radioiodine was higher than 90%. The mean radioiodine activity was 28.9 ± 3.4 mCi. The mean time between radioiodine performance and hyperthyroidism resolution was 3.6 ± 3.0 months, ranging from 1-12 months. After the first year, 33.9% of the patients were under hypothyroidism, 59.4% under euthyroidism, and 6.7% under hyperthyroidism. Among the nonresponders, the variables that showed statistical difference were the presence of multinodular goiter and the radioiodine activity (mean, 25.5 ± 6.5 mCi; median, 30 [15-30 mCi]). The cumulative rate of hypothyroidism was 48.9% over 20 years of follow-up. Radioiodine therapy is an effective and safe treatment. In Plummer disease, high rates of euthyroidism are expected after the radioiodine treatment. Therapeutic failure was observed mainly in patients with larger multinodular goiters treated with lower doses of radioiodine. The evolution to hypothyroidism was mostly observed in younger patients with larger and uninodular goiters.

Can Ethanol Ablation Achieve Durable Control of Neck Nodal Recurrences in Adults With Stage I Papillary Thyroid Cancer?

Results of ethanol ablation (EA) for controlling neck nodal metastases (NNM) in adult patients with papillary thyroid carcinoma (APTC) beyond 6 months have rarely been reported. We now describe outcome results in controlling 71 NNM in 40 node-positive stage I APTC patients followed for 66 to 269 months. All 40 patients were managed with bilateral thyroidectomy and radioiodine therapy and followed with neck ultrasound (US) for >48 months after EA. Cumulative radioiodine doses ranged from 30 to 550 mCi; pre-EA 27 patients (67%) had 36 additional neck surgeries. Cytologic diagnosis of PTC in 71 NNM selected for EA was confirmed by US-guided biopsy. EA technique and follow-up protocol were as previously described. The 40 patients had 1 to 4 NNM; 67/71 NNM (94%) received 2 to 4 ethanol injections (total median volume 0.8 cc). All ablated 71 NNM shrank (mean volume reduction of 93%); nodal hypervascularity was eliminated. Thirty-eight NNM (54%) with initial volumes of 12-1404 mm3 (median 164) disappeared on neck sonography. Thirty-three hypovascular foci from ablated NNM (pre-EA volume range 31-636 mm3; median 147) were still identifiable with volume reductions of 45% to 97% observed (median 81%). There were no complications and no postprocedure hoarseness. Final results were considered to be ideal or near ideal in 55% and satisfactory in 45%. There was no evidence of tumor regrowth after EA. Our results demonstrate that for patients with American Joint Committee on Cancer stage I APTC, who do not wish further surgery or radioiodine, and are uncomfortable with active surveillance, EA can achieve durable control of recurrent NNM.

Serum anti-Müllerian hormone is lower in patients with multiple radioiodine dose for treatment of pediatric thyroid cancer.

Treatment of patients with pediatric differentiated thyroid cancer (DTC) often involves radioiodine (RAI), which is associated with increased risks of short- and long-term adverse outcomes. The impact of RAI treatment on the female reproductive system remains uncertain. Anti-Müllerian hormone (AMH) is a marker of ovarian reserve and is related to fertility. The aim was to analyze the association between RAI and serum AMH level in women treated with RAI. We evaluated women with pediatric DTC treated with RAI at the age of ≤19 years. Serum AMH was measured. The study included 47 patients with a mean age of 25.1 years (12.4-50.8) at AMH measurement and follow-up of 11.8 ± 8.4 years. The mean RAI administered was 235 mCi (30-1150). Sixteen (34%) received multiple RAI doses (471 ± 215 mCi). Mean AMH level was 2.49 ng/mL (0.01-7.81); the level was 1.57 ng/mL (0.01-7.81) after multiple RAI doses and 2.99 ng/mL (0.01-6.63) after a single RAI dose (P = 0.01). Patients who received a cumulative RAI lower than 200 mCi had higher AMH levels (2.23 ng/mL, 0.39-7.81) than those who received more (1.0 ng/mL, 0.01-6.63; P = 0.02). In patients with similar cumulative RAI activities, administration of multiple RAI doses was significantly and independently associated with AMH level lower than the reference range for age (HR: 5.9, 1.55-52.2, P = 0.014) after age adjustments. Levels of AMH were lower after multiple RAI doses, especially after a cumulative RAI dose above 200 mCi. More studies are needed to clarify the impact of RAI on fertility considering its cumulative activity and treatment strategy.

SAT562 Metastatic Oncocytic (Formerly Hürthle Cell) Thyroid Carcinoma in a Patient With Birt-Hogg-Dubé Syndrome

Abstract Disclosure: S. Vaid: None. R. Klein: None. P. Veeraraghavan: None. D.M. Blakaj: None. A. Agrawal: None. J. Sipos: None. S.I. Sherman: None. J. Klubo-Gwiezdzinska: None. S. Gubbi: None. Introduction: Birt-Hogg-Dubé syndrome (BHD) is a rare, autosomal dominant disorder due to a germline loss-of-function mutation in the folliculin (FLCN) gene. Clinical manifestations include pulmonary cysts, renal cell carcinoma, and skin tumors, while tumors of other sites such as thyroid are uncommon. Here, we report an extremely rare case of oncocytic thyroid carcinoma (OTC) in a patient with BHD. Clinical case: A 55-year-old male with BHD noted a lump in his neck which was identified as a 3 cm right thyroid nodule on sonogram. Medical history only included BHD, which was diagnosed based on the presence of pulmonary cysts and two family members with BHD. No family members had thyroid tumors, and the patient denied any history of radiation exposure. Fine needle aspiration biopsy was indeterminate (Bethesda III). A total thyroidectomy and central lymph node (LN) dissection was performed as LN metastases were identified on intraoperative frozen section. Histopathology revealed 3 foci of OTC, largest being 3.8 cm, with extrathyroidal extension into fibroadipose tissue, 3/31 LN metastases with the largest deposit of 0.5 cm without extranodal extension. A 156.6 mCi dose of I-131 radioiodine (RAI) was administered. No uptake was noted on the post-therapy scan. Four months later, new right lateral cervical lymphadenopathy was noted on computed tomogram (CT). A right lateral selective neck dissection was performed, which identified 3/28 metastatic LNs without extranodal extension. Next generation gene sequencing testing of the metastatic tumor revealed the pathogenic FLCN (H429fs*27) variant, along with TP53 (R248Q), and DAXX (L666fs*29) pathogenic variants. Over the next 20 months, serum thyroglobulin increased from 1.8 ng/ml to 121 ng/mL (normal: 1.6 - 59.9 ng/mL). Several sub-centimeter lung nodules and new right cervical lymphadenopathy were noted on CT, and these lesions demonstrated increased uptake on fluorodeoxyglucose positron emission tomography (PET/CT) and on Ga-68 DOTATATE PET/CT scans. Due to close proximity to the right internal jugular vein, the cervical lymphadenopathy was deemed to be inoperable. Stereotactic radiation was administered to the neck, which resulted in substantial shrinkage of the neck metastases. The patient continues to be on active surveillance, with tyrosine kinase inhibitors or peptide receptor radionuclide therapy being potential future systemic therapy options in case of disease progression. Conclusion: Thyroid tumors have been occasionally reported in BHD. While most of them are papillary or follicular tumors, only one case of OTC in BHD has been previously reported in the literature [1]. This report underscores the importance of screening for thyroid neoplasms in patients with BHD. Reference: 1. Panagiotidis et al. World J Nucl Med. 2018;17(2):123-125 Presentation Date: Saturday, June 17, 2023

SAT519 Association of Free Thyroxine Level With Survival Outcome In Patients With Intermediate And High-Risk Differentiated Thyroid Cancer

Abstract Disclosure: R. Ghosh: None. S. Auh: None. S. Gubbi: None. P. Veeraraghavan: None. C. Cochran: None. L. Shobab: None. K.D. Burman: None. L. Wartofsky: None. J. Klubo-Gwiezdzinska: None. Background Total thyroidectomy followed by radioiodine (RAI) is a standard treatment for patients with intermediate and high-risk differentiated thyroid cancer (DTC). Long-term management consists of therapy with supraphysiologic doses of levothyroxine to suppress thyrotropin (TSH), as in vitro models have shown that TSH can act as a differentiation signal at physiologic concentrations, but as cancer proliferating stimulus in higher concentrations. On the other hand, preclinical studies have shown that thyroid hormones (T4/T3) can act as a growth stimulus in thyroid cancer cell lines. Moreover, supraphysiologic doses of T4/T3 are associated with an increased risk of atrial fibrillation and osteoporotic fractures. There are limited data on the role of elevated free T4 (FT4) on survival outcomes in patients with DTC. The goal of this study was to assess the association between FT4 levels and progression-free survival (PFS) in patients with intermediate-to-high-risk DTC. Material and Methods This cohort study was approved by the multi-institutional review board. Patients with DTC treated uniformly with total thyroidectomy and RAI between January 1, 1979, and March 1, 2015, and subjected to TSH suppression therapy, with at least 3 TSH and FT4 values available over time were included. The association between average FT4 level above the upper reference range (&amp;gt;1.8 ng/dl) at landmarks 6, 12, and 18 months was assessed by Kaplan-Meier survival curves. A Cox proportional hazards model was used to assess the contribution of competing risks such as age, sex, tumor size, lymph node, and distant metastases on PFS. Results The study included 382 patients, aged 46.6 ± 16.5 years, 245/382 (64.1%) women, treated with a median RAI dosage of 159 (110-410) mCi and followed for 8.5±6.2 years during which 132/382 (34.5%) experienced disease progression. During follow-up, 108/382 (28.3%) patients presented with an average FT4 of &amp;gt;1.8 ng/dl, while the remaining patients had FT4 within the normal range. Overall, elevated FT4 level was not associated with decreased PFS (HR 0.9, CI 0.54 -1.5, p=0.69), while age at diagnosis (HR 1.02, CI 1.004-1.04, p=0.01), tumor size (HR 1.15, CI 1.04 -1.28, p=0.01), lateral neck lymph node metastases (HR 2.9, CI 1.78 - 4.74, p&amp;lt;0.001), bone metastases (HR 4.87, CI 1.79 - 13.3, p=0.002) and brain metastases (HR 5.56, CI 2.54 - 12.2, p&amp;lt;0.001) were associated with shorter PFS. The landmark analysis performed to reduce the bias due to time-varying covariates at 6, 12, and 18 months confirmed these results. Conclusions Although high FT4 may stimulate thyroid cancer growth in vitro, elevated FT4 levels do not appear to worsen PFS. However, in managing patients with persistent DTC, clinicians must balance the benefits of TSH suppression with the potential detrimental effects of high FT4 on cardiovascular and bone health. Presentation Date: Saturday, June 17, 2023

Assessment of three different radioiodine doses for ablation therapy of thyroid remnants: Efficiency, complications and patient comfort.

I-131 radioiodine (RAI) ablation removes postoperative residual tissue and facilitates follow-up in low- and intermediate-risk differentiated thyroid cancer (DTC). Although low doses have been reported to be as effective as higher doses for ablation, the doses administered still vary depending on the patient and the practitioner. We aimed to evaluate the ablation efficiency, complications, and length of stay (LOS) of patients with DTC treated with 3 different doses for ablation. Patients with DTC who received RAI therapy were retrospectively reviewed. One hundred thirty patients with low-intermediate-risk, according to American Thyroid Association classification, without known lymph nodes or distant metastases were included. Patients were divided into 3 groups as 30 to 50 mCi, 75 mCi, and 100 mCi. Residue thyroid and salivary glands were evaluated from 9 to 12 months post-RAI I-131 scans. No significant difference was found between groups regarding ablation success (P = .795). In multivariable analyses, pretreatment thyroglobulin (hazard ratio = 0.8, 95% confidence interval 0.601-0.952, P = .017) and anti- thyroglobulin antibody (hazard ratio = 1.0, 95% confidence interval 0.967-0.998, P = .024) were 2 independent predictors of ablation success. The mean LOS was 2.1 ± 0.3, 2.6 ± 0.6, and 2.9 ± 0.4 days, respectively, (P = .001). LOS rates of ≥ 3 days were 13.2%, 54.3%, and 84.8%, respectively. Mild decreases in hemoglobin, white blood cell (WBC), and platelet counts were observed in all groups after 6 weeks without any clinically significant findings. A lower rate of change in WBC counts was observed in the 30 to 50 mCi group compared to others. There was no dose-dependent difference regarding the early complaints questioned. Ablation with 30 to 50 mCi provides benefits such as shorter LOS, better patient comfort, less salivary gland dysfunction, and less WBC suppression, thus reducing costs without decreasing efficacy.

Outcome of Radioiodine Treatment in Hyperthyroidism and Predictive Factors of Treatment Failure: A 10-Year Experience

Objective: To analyze the effectiveness of the first dose of radioiodine (I-131) treatment in patients with hyperthyroidism in Southern Thailand. The second objective was to predict the factors implicated in treatment failure. Materials and Methods: Patients with hyperthyroidism who received first dose of I-131 between January 2010 and December 2019 at Songklanagarind Hospital were enrolled in the present retrospective study. The data collected included age, gender, duration of the disease, type of disease, thyroid gland size (by palpation), type of antithyroid drug (ATD), ATD dose, and time of withholding ATD before and after I-131 treatment. The effectiveness of the first dose of I-131 treatment was assessed after six months of treatment. Treatment success was defined as a euthyroid or hypothyroid status. Results: One thousand four hundred twenty-four patients with hyperthyroidism at a median age of 44.5 years and including 73.2% women were included in this study. Graves’ disease was the most common cause at 95.8%. The median I-131 dose was 7 mCi. Six months after treatment, 703 patients or 49.4%, achieved treatment success, which increased to 859 patients (60.3%) after 12 months. The authors found three factors that influenced treatment failure, duration of disease of seven months or longer (p=0.001), thyroid gland size of 100 g or larger (p=0.004), and I-131 treatment dose 10 to 19 mCi (p=0.021). The patient cohort was divided into three groups based on thyroid gland size at less than 50 g, 50 to 99 g, and more than 100 g, the I-131 treatment dose that increased the success rate of treatment in each group was 5 mCi or more, 6 mCi or more, and 15 mCi or more, respectively. Conclusion: A single dose of I-131 could successfully treat hyperthyroidism. The duration of the disease, size of the thyroid gland, and the dose of I-131 treatment had a substantial impact on the result. Thus, the authors recommended early treatment with I-131 at a suitable dose for patients with hyperthyroidism. Keywords: Radioiodine treatment; I-131; Hyperthyroidism; First dose

The Prospective Implementation of the 2015 ATA Guidelines and Modified ATA Recurrence Risk Stratification System for Treatment of Differentiated Thyroid Cancer in a Canadian Tertiary Care Referral Setting.

Objective: To present clinical outcomes of the prospective implementation of the 2015 American Thyroid Association (ATA) guidelines for the management of thyroid nodules and differentiated thyroid cancer (DTC) using the modified ATA recurrence risk (RR) stratification system. Methods: We prospectively analyzed 612 patients with DTC treated between April 2017 and December 2021 in Calgary, Alberta. Each patient was prospectively assigned a modified ATA RR and American Joint Committee Cancer 8th edition stage. Initial risk stratification and consideration of the 2015 ATA guidelines guided surgical management as well as the indication for and dose of radioiodine (RAI) and other adjuvant therapies. Patients were assessed for their response to treatment (RTT) at 2-years postoperatively. Results: There were 479 patients who had 2-year follow-up data and were included in the study. Of these patients, there were 253 (53%) low-, 129 (27%) intermediate-, and 97 (20%) high-RR patients. Of these, 227 patients (47%) underwent total thyroidectomy (TTX) plus RAI, 178 (37%) underwent TTX only, and 74 (16%) underwent lobectomy. The RTT at 2 years was excellent for 89% (66) of patients with lobectomy, 84% (149) for TTX only, and 53% (121) for TTX plus RAI. Among 253 patients who were deemed low RR, 85% (216) had excellent RTT, 13% (32) indeterminate RTT, 2% (4) biochemical incomplete RTT, and 1 patient had structural incomplete RTT. The intermediate RR group had the following RTT outcomes: 64% (83) excellent, 23% (30) indeterminate, 6% (7) biochemical incomplete, and 7% (9) structural incomplete. The high RR group had the worst RTT outcomes, with 38% (37) excellent, 19% (18) indeterminate, 10% (10) biochemical incomplete, and 33% (32) structural incomplete RTT. Conclusions: The 2015 ATA RR stratification system is useful for predicting disease status at 2-year post-treatment in patients with DTC. The 2015 ATA guidelines and modified ATA RR stratification treatment recommendations may reduce thyroid cancer overtreatment by including lobectomy as a definitive treatment option for low-risk thyroid cancers and selective use of RAI for intermediate and high-risk patients.

Case report: combined pattern thyroid carcinoma

Thyroid cancer accounts for approximately 3% of all new cancer diagnoses per year globally.1 Papillary thyroid carcinoma (PTC) is the most common type, followed by follicular thyroid carcinoma (FTC).1 Recently, the simultaneous appearance of different histological variants in the same patient has been reported, being called combined pattern thyroid cancer, mixed tumors, hybrid tumors or compound tumors of the thyroid gland.2 Epidemiologically, combined pattern cancer is reported in less than 2% of cases, it presents the same proportion in men and women, and the age of presentation is between 18 and 45 years.3 Different associations are found, including mixed carcinomas: a) medullary cancer (CMT) and PTC; b) PTC and fasciitis-like stroma; c) CPT and CFT; and even combinations of CMT, CPT and CFT.4 Several studies suggest a more aggressive clinical behavior, which may be related to the coexistence of multiple patterns of aggressive variants, with early detection and rapid and aggressive treatment being of vital importance. It is based on surgical treatment, moderate-high dose radioiodine and TSH suppression (&lt;0.1mIU/L).4 This achieves a cure rate of up to 66% and survival three years after diagnosis of 90% and 10 years of 80% to 95%.

ODP531 Worsening of pretibial myxedema following repeated doses of radioiodine treatment in a patient with hyperthyroid Graves’ disease

Abstract Introduction The development of new-onset pretibial myxedema following radioiodine (RAI) treatment has been occasionally reported from the probable influences of thyrotropin receptor antibodies (TRAbs) similar to the RAI-associated Graves’ ophthalmopathy (GO). However, the worsening of pre-existing pretibial myxedema after RAI treatment has never been reported. Herein, we report an interesting case of fluctuating clinical course of pretibial myxedema following treatments of hyperthyroid Graves’ disease for over 3 years. Case Report A 49-year-old Thai woman with underlying hyperthyroid Graves’ disease with GO and pretibial myxedema for 1 year came to our hospital for relapsed hyperthyroidism and active, moderate-to-severe GO in 2019. A plague form of pretibial myxedema with indurated hyperpigmented lesion was found on both legs. Intravenous pulse methylprednisolone (IVMP) was given to control her active GO. Both GO and pretibial myxedema significantly improved after IVMP treatments. Then, RAI (30 mCi) was administered at 1 month later as a definitive treatment. Low dose of oral prednisolone (20 mg/ day) was also given before and after RAI treatment. Transient hypothyroidism developed at 4 months post-RAI and the estimated weights of the thyroid decreased from 60 grams to 30 grams. However, hyperthyroidism relapsed again within 6 months post-RAI treatment. At that time, her pretibial myxedema flared up slightly but her GO was still inactive. Eventually, a second dose of RAI (20 mCi) was given at 11 months apart from the first RAI administration. Low dose of oral prednisolone was also given. She developed post-radiation thyroiditis at 4 months after RAI with worsening of pretibial myxedema and mild exacerbation of GO. Topical corticosteroid ointment was given for pretibial myxedema and only local supportive measures was applied to treat GO. Finally, permanent hypothyroidism was achieved at 6 months after the second course of RAI. Currently, her pretibial myxedema is stable without further flareup. Conclusion Our case highlights the potential of RAI treatment to precipitate both GO and pretibial myxedema in patients with pre-existing skin lesions. Low dose prednisolone prophylaxis might not ensure preventative effect in exacerbation. Whether the risk of worsening of pretibial myxedema is higher in patients with persistent hyperthyroidism requiring a second dose of RAI is a question that warrants further studies. Presentation: No date and time listed

Alterations in Oral Microbiota of Differentiated Thyroid Carcinoma Patients With Xerostomia After Radioiodine Therapy.

Background and AimsOral xerostomia remains one of the most common complications of differentiated thyroid carcinoma patients (DTC) after radioiodine therapy (RAI). Environmental factors in the etiology of xerostomia are largely unknown. We aimed to characterize the oral microbiota signatures and related biological functions associated with xerostomia and identify environmental factors affecting them.MethodsSaliva was collected from 30 DTC patients with xerostomia (XAs), 32 patients without xerostomia (indicated as non-XAs) following RAI after total thyroidectomy, and 40 healthy people (HCs) for 16S rRNA sequencing analysis.ResultsThe oral microbiota of XAs and non-XAs exhibited significant differences in α and β diversities and bacterial taxa. The abundance of porphyromonas, fusobacterium, and treponema_2 were significantly higher in XAs, while the abundance of the streptococcus was lower in the microbiota of non-XAs. Fusobacterium, and porphyromonas were negatively correlated with unstimulated/stimulated whole salivary secretion (USW)/(SWS), while fusobacterium, porphyromonas, and treponema_2 genera levels were positively associated with cumulative radioiodine dose. PICRUSt2 and BugBase suggested a significant difference in the expression of potentially_pathogenic, anaerobic, gram_negative, the arachidonic acid metabolism, and lipopolysaccharide (LPS) biosynthesis between XAs and non-XAs, possibly interdependent on radioiodine-induced inflammation. NetShift analysis revealed that porphyromonas genus might play as a key driver during the process of xerostomia. Five genera effectively distinguished XAs from non-XAs (AUC = 0.87).ConclusionOur study suggests for the first time that DTC patients with xerostomia after RAI display microbiota profiles and associated functional changes that may promote a pro-inflammatory environment. Dysbiosis of the oral microbiota may contribute to exacerbating the severity of xerostomia. Our results provide a research direction of the interaction mechanism between oral microbiota alteration and the progress of xerostomia.

Analysis of Excellent Response, Persistent Disease and Recurrent Diseases of Radioiodine Treatment on Differentiated Thyroid Carcinoma Patients- 42 Years’ Experience at NINMAS

Background: Radioiodine treatment in thyroidectomized differentiated thyroid carcinoma (DTC) patients was introduced in the world in 1940s and in Bangladesh in 1980. Long experience of treatment and lifelong follow up of DTC patients with proper documentation of medical records enriched the archive of the thyroid division of National Institute of Nuclear Medicine &amp; Allied Sciences (NINMAS). Aims: To evaluate the response of radioiodine treatment in DTC patients at NINMAS and analyze the outcome and prognostic factors in this cohort of patients in a single institute of a developing country. Patients and Methods: This is a retrospective cohort study. A total of 7525 patients with DTC received RAI ablation therapy from 1980-2021 at NINMAS, among them 5448 patients were treated with radioiodine from 1980-2017. Data were obtained from the medical records of 3482 DTC patients who were followed up until 2021 and all relevant data were available. Demographical, histopathological, surgical, radioiodine ablation doses of 131I, serum biomarkers thyroglobulin (Tg), antithyroglobulin antibody (TgAb) and biochemical investigation data were analyzed systematically. Age, gender, tumor size, presence of local and distant metastases at presentation, extrathyroidal extension (ETE), disease recurrence, and cancer-specific survival were also evaluated. Risk stratifications for recurrence and staging were calculated for dosing of radioiodine. The single dose of radioiodine ranged from 30 mCi to 200 mCi was given according to the postsurgical risk assessment. Repeated doses of radioiodine were given in the cases of persistent disease (PD) and recurrent disease (RD). Results: The median age of DTC patients was 38 years, with a range of 5-87 years (39.90± 12.67 years), with the majority of patients falling within the 30-39 age group. The ratio of female to male was 3.74:1. Compared to the previous decade, patient number increased about 72 and 16-folds in relation to the 1980s and 1990s respectively at this institute. Papillary thyroid carcinoma (PTC) and follicular variant of thyroid carcinoma (FVPTC) together were evaluated in 3311(95.09%) cases and follicular thyroid carcinoma (FTC) was diagnosed in 171(4.91%). Excellent response (ER) was observed by a single dose of radioiodine ablation in 2853(81.94%) and PD and RD were noted in 388(11.14%) and 241(6.92%) respectively. Tg and TgAb levels at pre-therapy state were significantly higher in patients who had PD (P &lt;0.000) and RD (P &lt;0.000). Conclusion: Significant increase in the number of DTC patients was observed in the last two decades. ER was noted in 81.94% with a single dose of radioiodine. Serum Tg and TgAb are two prognostic factors for disease outcomes showing high Tg and TgAb in PD and RD cases. Bangladesh J. Nuclear Med. 25(2): 81-87, 2022

Ultrasound determination of pediatric thyroid mass.

Radioiodine therapy for Graves disease can be achieved with dosing based on estimated thyroid gland mass. Thyroid mass can be estimated using linear ultrasound measurements, and conversion factors for volume and density. The choice of conversion factors could impact estimated thyroid mass and thus administered radioiodine dose. The objective of this study was to define the relationship between thyroid mass estimated by ultrasound and measured thyroid mass following thyroidectomy. This was a retrospective, exempt study that included patients < 18 years of age with < 6 months between thyroid ultrasound and thyroidectomy January 2010-June 2020. Thyroid dimensions by ultrasound, thyroid mass at thyroidectomy and histopathological diagnosis were collected. Published conversion factors were used to estimate thyroid volume with conversion to mass using a density of 1.05g/cm3. Pearson correlations and Bland-Altman difference analyses were used to define the relationship between estimated mass and specimen weight. Linear regression was used to calculate an optimal conversion factor for estimating thyroid mass. We included 86 patients, 67 female (78%), with a mean age of 14.5 ± 3.15 years. Mass estimated using all tested conversion factors had similar strong, positive correlation with specimen weight (r = 0.95). The mean difference between thyroid mass estimated by ultrasound and measured mass ranged from - 0.34g (conversion factor = 0.523) to 1.69g (conversion factor = 0.554). The optimal simplified factor for estimation of thyroid mass for the study sample was 0.537. All published conversion factors for estimating thyroid mass based on linear ultrasound measurements produce good estimates of thyroid mass. Errors in estimated mass are less than 2g on average.

AN UNUSUAL CAUSE OF GAMMA CAMERA CONTAMINATION.

This report is of an unusual case of radioactive contamination of a gamma camera after scanning two individuals who had been treated 3 days prior with ablative doses of radioiodine (131I) for thyroid cancer. A combination of observed half-life and pulse-height spectroscopy were employed to identify the radio-contaminant. The source of the contamination was eventually found to be a single human hair, presumably contaminated by the individual sucking her hair while waiting for the scan to start. This case demonstrates that hair can be contaminated by saliva and potentially other bodily fluids in the post-ablation setting and that using physical characteristics, in this case the observed half-life and pulse-height spectroscopy, can be useful in identifying the radio-contaminant.