TY - JOUR ID - 12734 TI - Inaccuracy of Thyroid to Background Uptake Ratio in Evaluating Technetium-99m-pertechnetate Thyroid Uptake and Establishing an Improved Algorithm JO - Asia Oceania Journal of Nuclear Medicine and Biology JA - AOJNMB LA - en SN - 2322-5718 AU - Wang, Changyin AU - Zhao, Yanfen AU - Shen, Ying AD - Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Hubei, China AD - Department of Applied Mathematics, School of Mathematics and Statistics of Wuhan University, Hubei, China Y1 - 2019 PY - 2019 VL - 7 IS - 2 SP - 160 EP - 171 KW - Quantitative analysis KW - Sodium pertechnetate Tc-99m KW - Thyroid gland KW - Thyroid uptake KW - Uptake ratio of thyroid-to-background DO - 10.22038/aojnmb.2019.12734 N2 - Objective(s): The aim of this study was to explore the accuracy of thyroid to background uptake ratio (UR) in the evaluation of 99mTc-pertechnetate thyroid uptake (TcTU) and establishment of an improved algorithm. Methods: This study was conducted on the thyroid images of 322 patients with thyroid diseases and 67 controls. For the purpose of the study, URs of the images were calculated, and then corrected by standardized thyroid area size to establish a corrected uptake ratio (CUR). Subsequently, the accuracy between UR and CUR was compared. Results: The results of linear regression using weighted least squares (using TcTU as a dependent variable and CUR, UR, or thyroid area size as independent variables) showed that CUR (t=105.5, P=0.000), UR (t=31.9, P=0.000), and thyroid area size (t=15.9, P=0.000) are influential factors of TcTU. Furthermore, the standardized coefficient of CUR (β=0.983) was obviously higher than those of UR (β=0.851) and thyroid area size (β=0.629). The linear goodness-of-fit between CUR and TcTU (R=0.983) was better than that between UR and TcTU (R=0.851). In addition, the total concordance rate between CUR and TcTU (96.7%) was significantly higher than that between UR and TcTU (83.0%; χ2=42.9, P=0.000). Discordance rates of CUR in large thyroid area (1.4% vs. 13.4%, χ2=17.0, P=0.000) and small thyroid area (3.3% vs. 42.2 %, χ2=44.3, P=0.000), were significantly lower than that of UR. In the abnormal thyroid areas, the discordance rates of UR obviously increased as compared to those of CUR. The UR overestimated the thyroid uptake in small thyroid areas and underestimated it in large thyroid areas. Conclusion: Based on the findings, CUR is more accurate than UR in measuring 99mTcO4ˉ thyroid uptake; accordingly, it is more significant in the diagnosis of thyroid disease. UR - https://aojnmb.mums.ac.ir/article_12734.html L1 - https://aojnmb.mums.ac.ir/article_12734_64e2692ec362f71e7af2adf8b00115ca.pdf ER -