RT Journal Article
SR Electronic
T1 Predictive Factors of the Therapeutic Effect of I-131 Therapy for Hyperthyroidism
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 3029
OP 3029
VO 62
IS supplement 1
A1 Haruna Ikeda
A1 Miho Nishio
A1 Yuka Ochi
A1 Mika Tamura
A1 Katsuhiko Kato
YR 2021
UL http://jnm.snmjournals.org/content/62/supplement_1/3029.abstract
AB 3029Objectives: In patients with hyperthyroidism, the therapeutic effect of radioiodine (I-131) therapy is attained after several months, and the treatment period (the period from I-131 administration to cure) varies for each patient. If we can predict the therapeutic effect and the treatment period before I-131 therapy, it will be easier to develop a treatment plan after therapy, which in turn can help reduce anxiety in patients with hyperthyroidism. In this study, we investigated the factors that predict the therapeutic effect of I-131 therapy and treatment period in patients with hyperthyroidism. Methods: Thirty-seven patients with Graves’ disease were recruited and retrospectively evaluated in this study. Our final analysis, however, included 50 cases as 13 patients underwent I-131 therapy twice. The radiation dose administered during I-131 therapy was determined using the Marinelli-Quimby formula. We performed follow-up after I-131 therapy and examined the period until euthyroidism or hypothyroidism. Treatment failure was defined as persistent hyperthyroidism after 6 months of I-131 therapy. We collected data on potential influencing factors, including the mean thyroid computed tomography (CT) density; volume of the thyroid gland; 24-h iodine uptake rate; effective half-life; levels of free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), and TSH receptor antibody (TRAb); and thyroid-absorbed dose calculated using the Marinelli-Quimby formula. The mean thyroid CT density and thyroid volume were obtained by setting the region of interest over the entire thyroid gland for X-ray CT. We used Spearman’s rank correlation coefficient to assess the relationship between each of these factors and the treatment period. In addition, patients were classified into the successful group (euthyroidism and hypothyroidism) and the unsuccessful group (hyperthyroidism), respectively. The aforementioned factors were then compared between the two groups using the Mann-Whitney U test. P < 0.05 was considered statistically significant. Results: The treatment period was significantly correlated with the thyroid CT density (r = 0.577, p < 0.001), effective half-life (r = 0.437, p < 0.01), and TRAb level (r = -0.367, p < 0.05). However, the thyroid volume; 24-h iodine uptake rate; levels of fT3, fT4, TSH, and TRAb; and absolute dose did not correlate with the treatment period. In addition, the successful group had a significantly smaller thyroid volume and a higher thyroid-absorbed dose than the unsuccessful group. Conclusions: The thyroid CT density, effective half-life, and TRAb level are significantly associated with the treatment period (from I-131 administration to cure). Moreover, the thyroid volume and thyroid-absorbed dose are factors that influence the success of I-131 therapy in patients with hyperthyroidism.