Simplified Assessment of Radioiodine Biokinetics for Thyroid Cancer Patients: A Practical Approach Using Continuous External Radiation Monitoring

INTRODUCTION

The biokinetics of radioiodine (RAI) in thyroid cancer patients are complex. This study aims to develop a practical approach for assessing RAI biokinetics to predict patient discharge time and estimate radiation exposure to caregivers.

METHODS

We retrospectively reviewed data from patients with differentiated thyroid carcinoma undergoing RAI treatment. Serial radiation dose rates were dynamically collected during hospitalization and fitted to a biexponential model to assess the biokinetic features: RAI uptake fraction of thyroid tissue (Ft) and effective half-life of extra-thyroid tissue (Tet). Correlations with 99mTc thyroid uptake ratio (TcUR), radiation retention ratio (RR), renal function, and body mass index (BMI) were analyzed.

RESULTS

Thirty-five patients were enrolled. The derived Ft was 0.08 ± 0.06 and Tet was 7.57 ± 1.45 h. Pearson's correlation analysis revealed a significant association between Ft and both TcUR and RR (p < 0.05), while Tet correlated with renal function and BMI (p < 0.05).

CONCLUSION

This novel and practical method assessing RAI biokinetics demonstrates consistency with other parameters and related studies, enhancing the model reliability. It shows promise in predicting an appropriate discharge time and estimating radiation exposure to caregivers, allowing for modifications to radiation protection precautions to follow ALARA principle and minimize the potential risks from radiation exposure.

Immune Response Related to Lymphadenopathy Post COVID-19 Vaccination

Mass vaccination against coronavirus disease 2019 (COVID-19) is a global health strategy to control the COVID-19 pandemic. With the increasing number of vaccinations, COVID-19 vaccine-associated lymphadenopathy (C19-VAL) has been frequently reported. Current findings emphasize the characteristics of C19-VAL. The mechanism of C19-VAL is complicated to explore. Accumulated reports separately show that C19-VAL incidence is associated with receiver age and gender, reactive change within lymph nodes (LN), etc. We constructed a systematic review to evaluate the associated elements of C19-VAL and provide the mechanism of C19-VAL. Articles were searched from PubMed, Web of Science and EMBASE by using the processing of PRISMA. The search terms included combinations of the COVID-19 vaccine, COVID-19 vaccination and lymphadenopathy. Finally, sixty-two articles have been included in this study. Our results show that days post-vaccination and B cell germinal center response are negatively correlated with C19-VAL incidence. The reactive change within LN is highly related to C19-VAL development. The study results suggested that strong vaccine immune response may contribute to the C19-VAL development and perhaps through the B cell germinal center response post vaccination. From the perspective of imaging interpretation, it is important to carefully distinguish reactive lymph nodes from metastatic lymph node enlargement through medical history collection or evaluation, especially in patients with underlying malignancy.

Reversing "Flip-Flop" Phenomenon of 131 I and Glucose Avidity in RET-Fusion Positive Radioiodine-Refractory Thyroid Cancer Lesions After Treatment of Pralsetinib

ABSTRACT

A 61-year-old man presented with papillary thyroid cancer in radioiodine-refractory status after high-activity 131 I treatments following thyroidectomy. FDG-avid neck and pulmonary metastases but without 131 I-uptake were detected. CCDC6-RET fusion was identified from the tumor lesion. He was treated with pralsetinib, a RET inhibitor, followed by another high-activity 131 I therapy. Posttherapeutic scan displayed restoration of 131 I avidity at those lesions only shown on previous FDG PET/CT. Reduced FDG avidity of those lesions and decreased serum antithyroglobulin antibody titer were also noticed. This case illustrated successfully reinduced 131 I avidity in papillary thyroid cancer through redifferentiation with target therapy to suppress tumor RET overexpression.

Utilizing Proteomic Approach to Analyze Potential Antioxidant Proteins in Plant against Irradiation

Gamma-ray irradiation is an effective and clean method of sterilization by inactivating microorganisms. It can also be applied to induce anti-oxidants for future application. In this study, the mung bean (Vigna radiata) was exposed to gamma-ray irradiation under the dose of 0, 5 or 10 kGy. With increasing irradiation doses, the concentrations of malondiadehyde decreased while the levels of total flavonoids and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity increased. It has been shown that consuming flavonoids can provide protective effects. In addition, proteomic analysis identified several proteins having anti-oxidant activities in the 5 kGy irradiated group. These proteins are Apocytochrome f, Systemin receptor SR 160, DELLA protein DWARF8, DEAD-box ATP-dependent RNA helicase 9, ζ-carotene desaturase (ZDS), and Floral homeotic protein AGAMOUS. Our findings indicate that plants contain a variety of phytochemicals and antioxidant proteins which may effectively prevent oxidative stress caused by irradiated peroxidation.

Multikinase Inhibitors for the Treatment of Asymptomatic Radioactive Iodine-Refractory Differentiated Thyroid Cancer: Global Noninterventional Study (RIFTOS MKI)

Background: Sorafenib and lenvatinib are multikinase inhibitors (MKIs) approved for patients with radioactive iodine-refractory (RAI-R) differentiated thyroid cancer (DTC). There is no consensus on when to initiate MKI treatment. The objective of this study was to evaluate time to symptomatic progression (TTSP) in patients with RAI-R DTC for whom the decision to treat with an MKI was made at study entry. Methods: International, prospective, open-label, noninterventional cohort study (NCT02303444). Eligible patients had asymptomatic progressive RAI-R DTC, with ≥1 lesion ≥1 cm in diameter and life expectancy ≥6 months. The decision to treat with an MKI was at the treating physician's discretion. Primary endpoint was TTSP from study entry. Two cohorts were evaluated: patients for whom a decision to initiate an MKI was made at study entry (Cohort 1) and patients for whom there was a decision not to initiate an MKI at study entry (Cohort 2). Cohorts were compared descriptively. Results: The full analysis set (FAS) comprised 647 patients. The median duration of observation was 35.5 months (range <1-59.4). Of 344 MKI-treated patients, 209 received sorafenib, 191 received lenvatinib, and 19 received another MKI at some point. Median TTSP was 55.4 months (interquartile range [IQR] 18.6-not estimable [NE]) overall, 55.4 months (IQR 15.2-NE) in Cohort 1 (n = 169), and 51.4 months (IQR 20.0-NE) in Cohort 2 (n = 478). TTSP ≥36 months was achieved in 64.5% of patients overall, 59.5% of patients in Cohort 1, and 66.4% of patients in Cohort 2. Median overall survival from classification as RAI-R was 167 months and median progression-free survival from start of MKI therapy was 19.2 months and from start of sorafenib therapy 16.7 months. Among sorafenib-treated patients, 70% had dose modifications, 35% had a dose reduction, 89% experienced ≥1 treatment-emergent adverse event (TEAE), and 82% experienced ≥1 drug-related TEAE. Conclusions: This real-world study provides valuable insight into outcomes in patients with asymptomatic, progressive RAI-R DTC under observation or receiving MKI treatment. TTSP in the FAS provides insight into the current prognosis for patients with RAI-R DTC in the era of MKIs. Registration: NCT02303444.

A Rare Adverse Effect of the COVID-19 Vaccine on Autoimmune Encephalitis

Since countries commenced COVID-19 vaccination around the world, many vaccine-related adverse effects have been reported. Among them, short-term memory loss with autoimmune encephalitis (AE) was reported as a rare adverse effect. Since case numbers are limited, this brief report may draw the attention of the medical community to this uncommon adverse effect and serve as a reference for future vaccine improvement. However, given the high risk of adverse outcomes when infected with SARS-CoV-2 and the clearly favorable safety/tolerability profile of existing vaccines, vaccination is still recommended.

Incidental Finding of Moderna COVID-19 Vaccination-Related Axillary Lymphadenopathy on 201Tl Myocardial Perfusion Imaging

ABSTRACT

We presented here a 71-year-old man with a history of thyroid cancer post total thyroidectomy and 131I ablation and right renal cell carcinoma post right partial nephrectomy. He reported persistent chest tightness and pain after the first dose of the Moderna COVID-19 (mRNA-1273) vaccine. Thus, coronary heart disease was suspected, and the patient was referred for MPI (myocardial perfusion imaging). Focal 201Tl uptake in the left axillary region was found incidentally on MPI, and SPECT/CT revealed enlarged benign-looking lymph nodes. The diagnostic is in favor of reactive hyperplasia after the intramuscular injection of vaccine into left deltoid muscle.

Radioactive Iodine Treatment and the Risk of Long-Term Cardiovascular Morbidity and Mortality in Thyroid Cancer Patients: A Nationwide Cohort Study

(1) Background: This study aimed to investigate the association between radioactive iodine (RAI) and long-term cardiovascular disease (CVD) morbidity/mortality in thyroid cancer. (2) Methods: The study was conducted using data from the Taiwan National Health Insurance Database during 2000–2015. Thyroid cancer patients aged ≥20 years were categorized into RAI (thyroidectomy with RAI) and non-RAI (thyroidectomy only) groups. The Cox proportional hazard regression model and Kaplan–Meier method were used for analysis. (3) Results: A total of 13,310 patients were included. Kaplan–Meier analysis demonstrated that the two groups had similar cumulative risks of CVD (log-rank p = 0.72) and CVD-specific mortality (log-rank p = 0.62). On Cox regression analysis of different RAI doses, the risk of CVD was higher in the cumulative dosage >3.7 GBq (hazard ratio = 1.69, 95% confidence interval = 1.24–2.40, p < 0.001). (4) Conclusions: RAI was not associated with an increased risk of CVD in thyroid cancer. However, CVD surveillance is indicated in the patients receiving the cumulative RAI dosage above 3.7 GBq.

Effects of dose, intervention time, and radionuclide on sodium iodide symporter (NIS)-targeted radionuclide therapy

The sodium iodide symporter (NIS) mediates iodide uptake into thyrocytes and is the molecular basis of thyroid radioiodine therapy. We previously have shown that NIS gene transfer into the F98 rat gliomas facilitated tumor imaging and increased survival by radioiodine. In this study, we show that: (1) the therapeutic effectiveness of (131)I in prolonging the survival time of rats bearing F98/hNIS gliomas is dose- and treatment-time-dependent; (2) the number of remaining NIS-expressing tumor cells decreased greatly in RG2/hNIS gliomas post (131)I treatment and was inversely related to survival time; (3) 8 mCi each of (125)I/(131)I is as effective as 16 mCi (131)I alone, despite a smaller tumor absorbed dose; (4) (188)ReO(4), a potent beta(-) emitter, is more efficient than (131)I to enhance the survival of rats bearing F98/hNIS gliomas. These studies demonstrate the importance of radiopharmaceutical selection, dose, and timing of treatment to optimize the therapeutic effectiveness of NIS-targeted radionuclide therapy following gene transfer into gliomas.

In vivo imaging and radioiodine therapy following sodium iodide symporter gene transfer in animal model of intracerebral gliomas

Radioactive iodide uptake (RAIU) in thyroid follicular epithelial cells, mediated by the sodium iodide symporter (NIS), is the first rate-limiting step in iodide accumulation which provides a mechanism for effective radioiodide treatment for patients with thyroid cancer. We hypothesize that NIS gene transfer to non-thyroid tumor cells will enhance intracellular radioiodide accumulation and result in better tumor control. Here, we performed non-invasive tumor imaging and (131)I therapy studies using rats bearing intracerebral F98 gliomas that have been retrovirally transduced with human NIS. Our results show that: (1) NIS is expressed in the intracerebral F98/NIS gliomas; (2) F98/NIS gliomas can be imaged by (99m)TcO(4) (whose uptake is also mediated by NIS) and (123)I scintigraphy; (3) significant amounts of radioiodide were retained in the tumors at 24 h after (123)I injection; (4) RAIU and NIS expression in the thyroid gland can be reduced by feeding a thyroxine-supplemented diet; and (5) survival time was increased in rats bearing F98/hNIS tumors by (131)I treatment. These studies warrant further investigating tumor imaging and therapeutic strategies based on NIS gene transfer followed by radioiodide administration in a variety of human cancers.