Multifocal Nonmetastatic Radioactive Iodine Avidity on Whole Body Scan After Thyroidectomy for Thyroid Cancer.

Background/Objective: Non-metastatic radioactive iodine (RAI) uptake can complicate the interpretation of whole-body scan (WBS) for differentiated thyroid carcinoma (DTC) post-thyroidectomy. We present a patient with DTC whose follow-up WBS showed nonmetastatic multifocal avidity in skeletal tissue, an uncommonly reported site of RAI uptake. Case report: A 42-year-old woman underwent a right hemithyroidectomy, followed by completion thyroidectomy and RAI remnant ablation therapy, for a 4.8 cm thyroid tumor consistent with stage pT3aNxMx follicular thyroid cancer. Follow-up WBS showed intense activity in the thyroid bed, right breast, left medial subcortical acetabulum, and several vertebral bodies. Her biochemical and clinical findings were not suggestive of cancer recurrence. Further workup with SPECT/CT and MRI showed no focal vertebral lesions and identified the left femoral lesion as a benign peripheral nerve sheath. Diagnostic mammography and ultrasound showed no evidence of suspicious breast lesions. Neck ultrasound was clear with no suspicious masses or pathologic lymphadenopathy. She remained in remission on continued active surveillance. Discussion: Nonmetastatic RAI uptake on WBS has many causes, including functional sodium-iodide symporter expression in nonthyroidal tissues, radioiodine accumulation in tissues and bodily fluids, and benign tumors. False-positive uptake can decrease the utility of post-treatment WBS in low-risk patients. Careful clinical examination, biochemical and radiologic follow-up, and close active surveillance can help distinguish false-positive uptake from metastatic or recurrent disease. Conclusion: We describe an uncommon case of RAI uptake in skeletal tissues after thyroidectomy for DTC, and we outline the steps taken to rule out underlying metastases.

Therapeutic efficacies of remnant ablation and radioiodine adjuvant therapy in differentiated thyroid cancer.

BACKGROUND: Successful ablation in 131I therapy for differentiated thyroid cancer (DTC) includes both remnant ablation (RA) and radioiodine adjuvant therapy (RAT). This study aimed to differentiate between the therapeutic efficacies of RA and RAT, investigate the factors associated with their effectiveness, and assess their impact on prognosis. METHODS: This retrospective study included patients with DTC who underwent initial 131I therapy at our tertiary center. The successful RA (SRA) and successful RAT (SRAT) was determined based on the 131I-diagnostic whole-body scan (Dx-WBS), TSH-stimulated thyroglobulin (sTg) levels, and neck ultrasound at the 6th month after 131I therapy. The patients were divided into complete response and persistent/recurrent disease groups during the follow-up period. RESULTS: A total of 232 patients were included, 91.8% (213/232) of patients achieved SRA, only 8.1% (19/232) failed RA (FRA). Among the 213 patients in the SRA group, 70.4% (150/213) achieved SRAT and 29.6% (63/213) failed RAT (FRAT). Only pre-ablation sTg >10 ng/mL (OR = 46.968, 95% CI 9.731-226.699, P < 0.001) was an independent risk factor predicting the failure of RAT. The prognostic analysis included 215 patients, and 6.1% (13/215) were classified as persistent/recurrent disease at the last follow-up. Both pre-ablation sTg >10 ng/mL (HR = 4.765, 95% CI 1.371-16.566, P = 0.014) and FRAT (HR = 10.104, 95% CI 1.071-95.304, P = 0.043) independently predicted persistent/recurrent disease. CONCLUSIONS: RA is easy to achieve successfully, whereas RAT evaluation provides greater value than RA for prognosis prediction. For patients with low Tg levels and no imaging evidence of disease, routine Dx-WBS during follow-up has minimal significance.

TERT promoter mutations contribute to adverse clinical outcomes and poor prognosis in radioiodine refractory differentiated thyroid cancer.

Telomerase reverse transcriptase promoter (TERTp) mutations are associated with non-radioiodine avidity. However, the role of these mutations in the clinical outcomes of patients with radioiodine-refractory differentiated thyroid cancer (RAIR-DTC) remains unknown. Herein, we aim to analyze gene mutations and clinical manifestations to verify TERTp's role in driving disease progression to RAIR-DTC and clinical outcomes. Next-generation sequencing data and clinical data were obtained from 243 patients with DTC. Of the 25 patients with TERTp mutations, 80% (20/25) had RAIR-DTC. RAIR-DTC was significantly less prevalent in patients with BRAFV600E (9/143, 6.3%) than those with both BRAFV600E and TERTp mutations (14/17, 82.4%). Patients with RAIR-DTC harboring both BRAFV600E and TERTp mutations were more likely to have > 3 distant metastatic sites (85.7%, 12/14) than those with BRAFV600E alone (33.3%, 3/9). Only one patient with both BRAFV600E and TERTp mutations had non-RAIR-DTC. The time from initial radioactive iodine therapy to RAIR-DTC diagnosis was significantly shorter in patients with TERTp mutations than in those without. Patients with BRAFV600E and TERTp mutations progressed faster to RAIR-DTC than those with BRAFV600E alone (p < 0.01). Our findings suggest that molecular testing for TERTp and other mutations like BRAFV600E may inform early diagnosis, prognosis, and treatment strategies before progression to RAIR-DTC.

Potential application of [18F]AlF-PSMA-11 PET/CT in radioiodine refractory thyroid carcinoma.

BACKGROUND: Patients diagnosed with radioiodine refractory (RAI-R) thyroid carcinoma (TC) have a significantly worse prognosis than patients with radiosensitive TC. These refractory malignancies are often dedifferentiated, hindering the effectiveness of iodine-based imaging. Additionally, the role of metabolic imaging using [18F]FDG PET/CT is also limited in these cases, making adequate staging of RAI-R TC challenging. Recent case series have shown promising results regarding the role of the prostate-specific membrane antigen (PSMA) in TC. In this study we explored the value of [18F]AlF-PSMA-11 PET/CT in RAI-R TC. METHODS: In this phase II study, lesions detected on [18F]AlF-PSMA-11 PET were compared to findings from [18F]FDG PET/CT. Additionally, the serologic soluble prostate-specific membrane antigen (sPSMA) was measured using ELISA. PSMA-expression on tumor tissue in any available resection specimens was analysed with an immunostainer. RESULTS: Eight patients were included, with a total of 39 identified lesions based on PET imaging. [18F]AlF-PSMA-11 PET identified 30 of 39 lesions, and [18F]FDG PET identified 33 lesions, leading to a detection rate of 76.9% and 84.6%, respectively. Interestingly, while nine lesions were solely visualized on [18F]FDG, six were uniquely seen on [18F]AlF-PSMA-11 PET. While sPSMA was immeasurable in all female patients, no correlation was found between sPSMA in male patients and disease-related factors. In five out of eight patients immunohistology showed PSMA expression on the primary tumor. CONCLUSIONS: Although not all lesions could be visualized, [18F]PSMA-11 PET identified multiple lesions imperceptible on [18F]FDG PET. These results display the potential additional diagnostic role of PSMA-targeted imaging in patients with RAI-R TC. Trial registration number No. EudraCT 2021-000456-19.

Long-term biological effects after acute 131I-administration of two rat models (with and without thyroid).

PURPOSE: Radioiodine-131 (RAI or iodine-131) is one of the most frequently used radionuclides for diagnosis and therapy of thyroid diseases (90% of all therapies in nuclear medicine). In order to optimize the patient protection, it is important to evaluate the long-term biological effects of RAI therapy on non-target organs. MATERIALS AND METHODS: An experimental animal model has been adopted, it consists on miming RAI therapy. An activity of RAI has been administrated in two models of Wistar rats: the first model with an intact thyroid gland (Thy + model), and the second one was thyroidectomized (Thy- model). For each model, 6 rats were orally contaminated with a solution 18.5 ± 1MBq of [131I]NaI and 6 others rats were used as controls. The 24 rats have been placed in individual cages for a period of 08 months then they were euthanized. The blood was collected by cardiac puncture and all organs were immediately removed. A fraction of thyroid, liver, kidneys and testicles was put in vials containing formaldehyde (10%) for histological investigation. RESULTS: Histological observations show some liver disorders more accentuated in the case of the Thy- model, the appearance of kidney tissue effects (hemosiderin deposits, fibrosis and glomerular necrosis) for both models and an absence of any anomaly for the testicles slides. The disturbance of blood parameters specific to each organ has been revealed. CONCLUSIONS: Long-term biological effect of 131I-administration shows the appearance of various histological disorders confirmed by disturbances in hepatic and renal functions.

Long-Term Outcome of Low- and High-Dose Radioiodine for Thyroid Remnant Ablation.

OBJECTIVE: We conducted a prospective randomized clinical trial to compare the efficacy of low- and high-dose radioiodine for remnant ablation in patients with low-risk differentiated thyroid cancer (DTC) in China. The first-stage results showed equivalence was observed between the two groups. Here, we report recurrence and survival at 3-5 and 6-10 years and biochemical parameters. DESIGN, PATIENTS AND METHODS: Between January 2013 and December 2014, adult patients with DTC were enroled. Patients had undergone total or near-total thyroidectomy, with or without cervical lymph node dissection, with tumour stages T1-T3 with or without lymph node metastasis, but without distant metastasis. Patients were randomly assigned to the low-dose (1850 MBq) or high-dose (3700 MBq) radioiodine group. They were then followed up for 3-5 and 6-10 years. Data on biochemical abnormalities, recurrence and survival were analysed using Kolmogorov-Smirnov and χ2 tests. RESULTS: The data of 228 patients (mean age = 42 years; 70.6% women) were analysed, with 117 patients in the low-dose group and 111 in the high-dose group. There were no significant differences in biochemical abnormalities, recurrence, or survival rates at the 6-10-year follow-up (all p > .05). Nine patients experienced recurrence in the low-dose group (8.7%), while eight patients experienced recurrence in the high-dose group (8.2%). The survival rates were 100% and 98.2% in the low- and high-dose groups, respectively. CONCLUSIONS: The long-term effectiveness and safety of low-dose (1850 MBq) radioiodine are the same as those of high-dose (3700 MBq) radioiodine for thyroid remnant ablation in Chinese patients with low-risk DTC.

Long-Term Outcome of Patients with Low-Risk Differentiated Thyroid Cancer Treated with Total Thyroidectomy Alone.

BACKGROUND: Differentiated thyroid carcinoma (DTC), mainly papillary (PTC), at low risk of recurrence is currently managed with active surveillance strategies or less aggressive surgeries. However, total thyroidectomy with 131I treatment is still performed both if these tumors are diagnosed before or occasionally after surgery. This real-life study aimed to evaluate the rate of biochemical, structural, and functional events in a large series of consecutive DTCs at low risk of recurrence treated by total thyroidectomy, but not with 131I, in a medium-long-term follow-up. PATIENTS AND METHODS: We evaluated clinical-pathologic data of 383 consecutive patients (2006-2012) with unifocal DTC [T1a/b(s)] at low risk of recurrence, treated with total thyroidectomy but without lymph node dissection and 131I treatment after surgery. We evaluated if structural, biochemical, and functional events were detected during the follow-up. RESULTS: Females accounted for 75.7% of our study group, and the median age was 50 years. The median tumor dimension was 0.4 cm (range 0.1-1.2). Most of the patients had a unifocal T1a tumor (98.9%), and 73.6% had a classic variant of PTC. We divided the patients according to the absence (group A-n = 276) or presence (group B-n = 107) of interfering TgAb at first control after surgery. After a median follow-up of 10 years, no structural events were detected. Sixteen out of three hundred and eighty-three (4.2%) patients developed biochemical events: 12/276 (4.3%) in group A and 4/107 (3.7%) in group B. The median time elapsed from surgery to detecting a biochemical event was 14.5 and 77.5 months in groups A and B, respectively. No patients performed additional treatments and were followed up with an active surveillance strategy. CONCLUSIONS: This study confirmed that patients with DTC at low risk of recurrence showed an excellent outcome in a medium long-term follow-up since no structural events were diagnosed. Significant variations in Tg/TgAb were detected in a few cases, all managed with an active surveillance strategy without the need for other treatments. Therefore, a relaxed follow-up with neck ultrasound and Tg/TgAb measurement is enough to early identify those very unusual cases of recurrence.

Effect of Presence of Uni- or Bilateral Thyroid Adenoma on Recovery of Pituitary-Thyroid Axis and Creatinine Concentration in Radioiodine-Treated Cats.

Radioiodine therapy (RAIT) is the gold standard for treatment of hyperthyroidism in cats. The aim of this study was to evaluate the effect of the presence of uni- or bilateral thyroid adenoma on changes in total thyroxine (TT4), thyroid-stimulating hormone (TSH), and creatinine concentration over a period of 6 to 12 months following RAIT. Fifty-one hyperthyroid cats presented for RAIT between April 2021 and April 2022 were prospectively enrolled. Cats with an increased creatinine concentration (creatinine ≥ 140 µmol/L), renal morphology abnormalities, and suspected thyroid carcinoma were excluded. TT4, TSH, and creatinine were determined before and one week and one, three, six, and twelve months following RAIT. The effects of the re-examination timepoint following RAIT and the presence of uni- or bilateral thyroid adenoma based on technetium-99m scintigraphy on TT4, TSH, and creatinine were analysed by mixed effects modelling. Cats with bilateral adenoma had significantly higher TSH concentrations after RAIT compared to those with unilateral adenoma. TT4 concentration significantly decreased one week (p < 0.001) and again one month following RAIT (p < 0.001). TSH and creatinine concentration significantly increased one month post RAIT (both p < 0.001). As indicated by an increase in TSH concentration, the pituitary-thyroid axis needs a minimum of one month post RAIT to recover from hyperthyroidism-induced suppression, but hypothyroidism necessitating levothyroxine supplementation might not be diagnosed before 6 or even 12 months post RAIT. Although creatinine did not increase significantly after one month post RAIT in this cohort, an increased creatinine concentration was detected at later timepoints in individual cats.

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.

Vitamin D receptor polymorphisms associate with the efficacy and toxicity of radioiodine-131 therapy in patients with differentiated thyroid cancer.

BACKGROUND: Radioiodine-131 (I-131) therapy is the common postoperative adjuvant therapy for differentiated thyroid cancer (DTC) However, methods to evaluate the efficacy and toxicity of I-131 on DTC are still lacking. OBJECTIVE: To evaluate the association between vitamin D receptor (VDR) gene polymorphisms and the efficacy and toxicity of I-131 in DTC patients. METHODS: A total of 256 DTC patients who received I-131 therapy were enrolled. The patients were divided into effective group and ineffective group. 4 single nucleotide polymorphisms (SNPs) (rs7975232, rs731236, rs1544410 and rs10735810) of VDR were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) Cell counting kit-8 (CCK-8) and flow cytometry were used to detect the proliferation and apoptosis of thyroid cancer cells. RESULTS: Patients in effective group had more CC genotype of rs7975232 and GG genotype of rs10735810 compared with patients in ineffective group They were also independent factors for influencing the efficacy of I-131. PTC-1 and FTC-133 cells transfected with CC genotype of rs7975232 showed lower proliferative activity and higher apoptosis rate after being treated with I-131 In addition, patients with CC genotype at rs7975232 had fewer adverse reactions after I-131 treatment. CONCLUSIONS: VDR gene polymorphisms may be associated with the efficacy and toxicity of I-131 in DTC patients, which will help to personalize the treatment for patients.

Efficacy and safety of targeted therapy for radioiodine-refractory differentiated thyroid cancer: a meta-analysis.

PURPOSE: To evaluate the efficacy and safety of current targeted drug therapies for radioiodine-refractory differentiated thyroid cancer (RR-DTC). METHODS: This was a meta-analysis of relevant randomized controlled trials (RCTs) and single-arm studies searched across PubMed, Embase, Cochranes, and Web of Sciences up to September 12, 2023. Stata15.0 software was used to assess overall survival (OS), progression-free survival (PFS), disease control rate (DCR), objective response rate (ORR), and adverse effects (AEs). The Cochrane Bias Risk tool was used to assess literature quality and trial bias and RevMan 5.4 was used to generate a quality assessment map. RESULTS: A total of 8 RCTs and 17 single-arm studies with 3,270 patients on 7 drugs-vandetanib, sorafenib, lenvatinib, cabozantinib, apatinib, donafenib, and anlotinib-were included. Targeted therapy with these drugs effectively prolonged PFS and OS in patients with RR-DTC with overall HRs of 0.35 (95% CI 0.23-0.53, P < 0.00001) and 0.53 (95% CI 0.32-0.86, P < 0.00001), respectively. ORR and DCR were also prolonged, with overall RRs of 27.63 (95% CI 12.39-61.61, P<0.00001) and 1.66 (95% CI 1.48-1.86, P<0.00001), respectively. The subgroup analysis using Effect Size (ES) showed that apatinib had the best effect on ORR with an ES of 0.66 (95% CI 0.49-0.83, P<0.00001) and DCR with a ES of 0.95 (95% CI 0.91-1.00, P<0.00001). Common drug adverse effects included hypertension, diarrhea, proteinuria, and fatigue. CONCLUSION: The currently used targeted drug therapies for RR-DTC can significantly improve clinical outcomes and the new drug apatinib demonstrates promise for potentially superior performance.

Excellent RAI therapeutic response on a patient presenting skull metastasis of follicular thyroid cancer after 15 years.

Bone is the second most common site of metastasis for differentiated thyroid carcinoma (DTC). Bone metastasis (BMs) occur in about 10% of patients with DTC and is observed more often in follicular thyroid carcinoma (FTC) (7-28%) than papillary thyroid carcinoma (PTC) (1-7%). Bone metastasis is associated with unfavorable clinical outcomes mainly including skeletal-related events (SREs), such as pathologic fractures, bone pain, spinal cord compressions, and hypercalcemia, which negatively impact the quality of life of patients and reduce their life expectancy. Patients with BMs from DTC require comprehensive and multimodal treatment approaches, including radioiodine (RAI) therapy, palliative care, surgery, external beam radiotherapy, and targeted drug therapy. RAI therapy is the first-line treatment, despite being rather ineffective, especially in large BMs. The response to RAI therapy, either alone or in combination with BM focal treatment depends on iodine avidity. This study reports a rare case of metachronous skull bone metastasis from FTC in a 72-year-old female patient 15 years after initial treatment. The patient had an excellent response to RAI therapy, which resulted in the abnormal uptake disappearing. Following treatment, the patient has been disease-free for six years. This case confirms that a complete response to RAI treatment for BM depends on the degree of dedifferentiation of cancer cells, which highlights the need for long-term follow-up, especially for FTC patients.

Neonatal Thyrotoxicosis in Infants of Mothers with Graves' Disease Treated for Radioiodine-Induced Hypothyroidism: A Literature Review.

Fetal and neonatal thyrotoxicosis occurs in up to 5% of pregnancies in mothers with Graves' disease (GD). This condition is caused by stimulating antibodies against the thyrotropin receptor (TRAbs) that cross the placenta and may stimulate the fetal thyroid, typically in the second half of pregnancy. GD is often treated with radioiodine, resulting in hypothyroidism in most patients, but TRAbs can persist for several years. Even if a pregnant mother is hypothyroid after radioiodine therapy or surgery, her TRAbs can still, although rarely, induce fetal hyperthyroidism. In this review, we first present two cases of neonatal hyperthyroidism in mothers with GD who became hypothyroid after prior radioiodine therapy, identified through a 10-year analysis of the National Perinatal System in Slovenia. Based on these cases, we provide an overview of existing data on this rare clinical condition in neonates. We also discuss the underlying mechanisms and clinical outcomes based on currently available data. In conclusion, our review highlights the importance of careful monitoring during pregnancy in all women with GD, even in those well managed after radioiodine therapy or surgery.

Prognostic factors in children and adolescents with differentiated thyroid cancer treated with total thyroidectomy and radioiodine therapy: a retrospective two-center study from China.

Purpose: This two-center study aimed to explore the main prognostic factors affecting the final disease status in children and adolescents with differentiated thyroid cancer (caDTC) following total thyroidectomy and radioiodine therapy (RAIT). Materials and methods: All caDTC patients from two centers in the period from 2004-2022 were retrospectively included. At the last follow-up, the patients' disease status was assessed and classified as an incomplete response (IR) or as an excellent or indeterminate response (EIDR). Then, the difference in preablation stimulated thyroglobulin (ps-Tg) levels between the two groups was compared, and the threshold for predicting IR was determined using receiver operating characteristic (ROC) analysis. Moreover, univariate and multivariate analyses were conducted to identify the factors influencing the patients' ultimate disease outcomes. Results: A total of 143 patients (98 females, 45 males; median age 16 years) were recruited. After a median follow-up of 42.9 months, 80 patients (55.9%) exhibited an EIDR, whereas 63 patients (44.1%) exhibited an IR. Patients with an IR had significantly greater ps-Tg levels than did those with an EIDR (median ps-Tg 79.2 ng/mL vs. 9.3 ng/mL, p<0.001). The ROC curve showed that ps-Tg ≥20 ng/mL was the most accurate for predicting IR at the last follow-up. According to multivariate analysis, only ps-Tg, T stage and the therapeutic response to initial RAIT were significantly associated with IR. Conclusion: In caDTC patients, the ps-Tg level, T stage, and response to initial RAIT are critical final outcome indicators.

Data-Driven Thyroglobulin Cutoffs for Low- and Intermediate-Risk Thyroid Cancer Follow-Up: ITCO Real-World Analysis.

CONTEXT: The utility of thyroglobulin (Tg) in the follow-up of differentiated thyroid cancer (DTC) patients has been well-documented. Although third-generation immunoassays have improved accuracy, limitations persist (interfering anti-Tg antibodies and measurement variability). Evolving treatment strategies require a reevaluation of Tg thresholds for optimal patient management. OBJECTIVE: To assess the performance of serum Tg testing in two populations: patients receiving total thyroidectomy and radioiodine remnant ablation (RRA), or treated with thyroidectomy alone. DESIGN: Prospective observational study. Setting. Centers contributing to the Italian Thyroid Cancer Observatory (ITCO) database. PATIENTS: We included 540 patients with 5 years of follow-up and negative anti-Tg antibodies. INTERVENTIONS: Serum Tg levels assessed at 1-year follow-up visit. MAIN OUTCOME MEASURE: Detection of structural disease within 5 years of follow-up. RESULTS: After excluding 26 patients with structural disease detected at any time point, the median Tg did not differ between patients treated with or without radioiodine. Data-driven Tg thresholds were established based on the 97th percentile of Tg levels in disease-free individuals: 1.97 ng/mL for patients undergoing thyroidectomy alone (lower than proposed by the MSKCC protocol and ESMO Guidelines, yet demonstrating good predictive ability, with a negative predictive value (NPV) of 98%) and 0.84 ng/mL for patients receiving post-surgical RRA. High sensitivity and NPV supported the potential of these thresholds in excluding structural disease. CONCLUSIONS: This real-world study provides evidence for the continued reliability of 1-year serum Tg levels. The data-driven Tg thresholds proposed offer valuable insights for clinical decision-making in patients undergoing total thyroidectomy with or without RRA.

Subjective and objective effects of radioiodine therapy on the sense of smell.

PURPOSE: Evaluating the impact of radioiodine therapy (RIT) on olfactory function in thyroid cancer patients through quantitative and qualitative olfactory tests. METHOD: In this cohort study, patients with thyroid cancer were included. Demographic, clinical, and laboratory data were collected. To subjectively evaluate the olfactory changes aftter RIT, the Visual Analog Scale (VAS), Self-Reported Mini-Olfactory Questionnaire (self-MOQ), and the University of Washington Quality of Life Questionnaire (UW-QOL) were assessed. Out of UW-QOL questions those related to saliva, taste, and overall health condition were analysed. For objective assessment, patients underwent both the Butanol Threshold Test (BTT) and the a version of Smell Identification Test (SIT). Patients were assessed before, one month, and six months after RIT. RESULTS: Ninety eight patients were included (Male = 17). A statistically significant decrement was observed in olfaction based on the VAS, between the baseline and one (pvalue = 0.015) and six months (pvalue = 0.031) of follow-up. Additionally, saliva (pvalue = 0.001), taste (pvalue = 0.000), and overall health condition (pvalue = 0.010) significantly decreased one-month after RIT. The measures were not different between the baseline and 6-month follow up and the improvement of index of taste was significant from 1-month to 6-months follow ups (pvalue = 0.000). However, none of the objective tests (the BTT and the SIT) indicated a significant decline in olfaction during the follow up. CONCLUSION: A subjective RIT related decrease in smell function, taste, and saliva production was documented without any objective olfactory dysfunction.

Normal reference values for Tc-99m pertechnetate thyroid uptake in northern Iranian population: A single-center experience.

Background: The normal reference values for the thyroid uptake of radioactive iodine and Tc-99m pertechnetate in euthyroid patients vary by geographical location as well as the amount of iodine intake in the diet. The present study examines the normal reference values for thyroid uptake of Tc-99m pertechnetate in the North of Iran. Methods: The participants of this study were 64 patients (all over 20 years of age) who had referred to the Nuclear Medicine Center of the Shahid Beheshti Hospital for thyroid scan over the period between March 2018 and May 2020. It is worth mentioning that relying on laboratory test results, only patients with normal thyroid function were included in this cross-sectional study. Results: The median, the 5th and 95th percentiles and thyroid uptake range of 99mTc-pertechnetate in euthyroid patients were 0.9, 0.6 to 1.8% and 0.54 - 1.80%, respectively. Conclusion: The percentage of uptake in the thyroid gland in each geographical area varies based on race and diet content, so it is necessary to determine the percentage of uptake in each specific region and even check it periodically.

Effect of recombinant human thyroid stimulating hormone on radioactive iodine uptake by thyroid carcinoma in dogs.

BACKGROUND: The high doses of radioiodine-131 (131I) and, subsequently, the high radioactive burden for dog and environment warrants optimization of 131I therapy in dogs with thyroid carcinoma (TC). HYPOTHESIS/OBJECTIVES: To evaluate the effect of a revised protocol with recombinant human thyroid stimulating hormone (rhTSH) on tumor radioactive iodine uptake (RAIU) in dogs with TC. ANIMALS: Nine client-owned dogs diagnosed with TC. METHODS: A prospective cross-over study in which tumor RAIU was calculated and compared at 8 hours (8h-RAIU) and 24 hours (24h-RAIU) after injection of radioactive iodine-123 (123I), once with and once without rhTSH (ie, 250 µg, IM, 24 and 12 hours before 123I) in each dog. Simultaneously, serum total thyroxine (TT4) and TSH were measured at baseline (T0), and 6 (T6), 12 (T12), 24 (T24), and 48 hours (T48) after the first rhTSH administration. RESULTS: Tumor RAIU was significantly higher at 24 hours with rhTSH compared to no rhTSH (mean difference = 8.85%, 95% CI of [1.56; 16.14]; P = .03), while this was non-significant at 8 hours (mean difference = 4.54%, 95% CI of [0.35; 8.73]; P = .05). A significant change of serum TT4 (median difference T24 - T0 = 35.86 nmol/L, interquartile range [IQR] = 15.74 nmol/L) and TSH (median difference T24 - T0 = 1.20 ng/mL, IQR = 1.55 ng/mL) concentrations occurred after administration of rhTSH (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Recombinant human TSH could optimize 131I treatment in dogs with TC by increasing tumor RAIU and thus 131I treatment efficacy.

Blood Micro-sampling: An alternative blood collection method for radioiodine therapy dosimetry.

PURPOSE: Collecting venous blood samples from patients post administration of high therapeutic activities results in radiation exposure to staff collecting the blood. This study investigated the use of finger-tip capillary-blood collection as an alternative to the venous-blood collection method recommended by the European Association of Nuclear Medicine (EANM) dosimetry protocol for quantifying 131I concentration in the critical organ after therapeutic dose of 131I. METHODS: The study included differentiated thyroid cancer patients referred to a thyroid cancer centre at St James's Hospital, Ireland, for therapeutic and diagnostic oral administration of 131I. The 15 patients recruited for this study provided 30 venous and capillary paired-blood samples. The activity concentration of the blood samples was compared between the type of blood (venous vs capillary) and the geometry/volume of the blood (1.0 ml versus 0.03 ml). Other variables were also investigated including administered activities, dose to staff performing the sampling, duration of sampling and time since administration. RESULTS: Blood samples were taken at 2.0-91.9 h post administration using 0.2 ± 0.0 GBq (n = 2) or 4.0 ± 0.1 GBq (n = 28) 131I activities. There was no significant difference found between different blood sampling types (-1.0 ± 4.3 %, p = 0.223), different blood volumes (-3.2 ± 10.0 %, p = 0.070), or between their combination. No significant correlation was found between the percentage differences and investigated parameters. CONCLUSION: A high degree of accuracy was achieved with blood radioactivity quantified using capillary blood collection using the finger-prick method. Further validation of the method would be required prior to implementation, to investigate patient specific factors which may affect accuracy.