ObjectiveNegative Tc-99m-pertechnetate uptake of the thyroid bed indicates the absence or a small volume of remnant thyroid tissue (RTT) after total thyroidectomy (TT). The aim of this study is to evaluate the predictive value of negative Tc-99m-pertechnetate scintigraphy for excellent response (ER) to radioactive iodine therapy (RIT) in low- to intermediate-risk differentiated thyroid cancer (DTC) patients.PatientsOne-hundred and eighty-nine low- to intermediate-risk DTC patients who underwent TT, RIT with a single dose of 30mCi and suppressive therapy with thyroid-stimulating hormone (TSH) from July 2015 to February 2016 in our hospital were retrospectively evaluated. Tc-99m-pertechnetate thyroid scintigraphy was performed just before RIT and images were reported dichotomously as negative or positive. The response of patients was assessed for 23.23.8 months after RIT and dichotomized as excellent response (ER) or non-excellent response (NER). Tc-99m-pertechnetate uptake, age at diagnosis, gender, multifocality, T stage, N stage, preablative stimulated thyroglobulin (ps-Tg), and TSH were explored as potential predictors for ER.Results80.68% (71/88) of patients with negative Tc-99m-pertechnetate uptake achieved ER. When patients were evaluated according to different ps-Tg levels, we found that 94.83% (55/58) of patients with ps-Tg < 1ng/ml and negative Tc-99m-pertechnetate uptake achieved ER. Multivariate Cox regression analysis revealed that ps-Tg (P=0.0001) and Tc-99m-pertechnetate uptake (P=0.0473) were independent predictors for ER.Conclusions In addition to ps-Tg, negative Tc-99m-pertechnetate uptake is also a significant independent predictor for an excellent response in low- to intermediate-risk patients. It may be possible to omit RIT in patients with ps-Tg < 1ng/ml and concurrent negative Tc-99m-pertechnetate uptake.
[1]Jilin Univ, China Japan Union Hosp, Dept Nucl Med, Changchun, Jilin, Peoples R China.
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