99mTc-pertechnetate-avid metastases from differentiated thyroid cancer are prone to benefit from 131I therapy

Abstract

The aim of this study is to determine the contribution of neck and chest 99mTc-pertechnetate scan to the management of postoperative patients with suspicious metastatic differentiated thyroid cancer (DTC), particularly to the prediction of response to radioiodine (131I) therapy. Just before 131I administration, a total of 184 postoperative DTC patients with stimulated serum thyroglobulin (ssTg) >10 ng/mL were enrolled to undergo neck and chest 99mTc-pertechnetate scan, which were directly compared with post-therapeutic 131I scan to determine the concordance of site and number of metastatic lesions. The percentage changes in ssTg between 99mTc-pertechnetate-avid group and 99mTc-pertechnetate-nonavid group were compared, and the response to 131I in both groups was analyzed according to the nature of 99mTc-pertechnetate avidity as well. The percentages of concordance between 99mTc-pertechnetate and 131I scan in detecting metastases were 65.7% and 26.0% in per-patient and per-site analyses with low unweighted kappa, respectively. 99mTc-pertechnetate scan led to a change in therapeutic decision making in 19/184 (10.3%) patients. In 72 patients with 131I-avid metastases, the ssTg in 99mTc-pertechnetate-avid group (n = 13) decreased significantly compared with that in 99mTc-pertechnetate-nonavid group (n = 59) (median: −81.56% vs −48.14%; Z = −4.276, P = .000). The difference of therapeutic response between 99mTc-pertechnetate-avid group and 99mTc-pertechnetate-nonavid group was statistically significant (χ2 = 8.4; P = .03). Although the consistency between 99mTc-pertechnetate scan before 131I administration and post-therapy 131I scan in detecting metastases is low, identifying metastases in postoperative DTC patients with elevated ssTg via 99mTc-pertechnetate scan prior to 131I therapy provides incremental value for therapeutic decision making. Notably, patients with 99mTc-pertechnetate-avid metastases may be more prone to benefit from 131I therapy than those with 99mTc-pertechnetate-nonavid metastases.

Appropriate Use Criteria for Nuclear Medicine in the Evaluation and Treatment of Differentiated Thyroid Cancer

“…In addition, the authors showed that patients with concordant lesions had a much greater reduction in Tg levels than did those who had IA lesions that were negative on TcWBS. This correlation makes sense as reasoned by the authors, who explained that greater uptake of therapeutic 131 I would be expected in 99m Tc-pertechnetate-avid lesions (125). These results were confirmed in an observational cohort of 56 patients (128).…”

“…The sensitivity and specificity of TcWBS for lymph node metastases was 60% and 99%, respectively, and for distant metastases was 37% and 99%, respectively. In another study of 184 patients with DTC after thyroidectomy, 99m Tc pertechnetate neck and chest imaging combined with SPECT/CT had an overall concordance rate of 65.7% with a planar post-131 I therapy whole-body 131 I scan combined with SPECT/CT when metastases of all types (nodal, lung, bone) were included (125). In addition, the authors showed that patients with concordant lesions had a much greater reduction in Tg levels than did those who had IA lesions that were negative on TcWBS.…”

“…Under the stimulation of TSH, 99m Tc-pertechnetate can demonstrate postthyroidectomy benign remnant tissue and, in some cases, coexistent DTC tissue before RAI therapy. It can also show metastatic DTC on subsequent diagnostic imaging and may provide some insight into the ability of DTC to concentrate iodine (125).…”

Thyrotoxicosis with concomitant thyroid cancer

“…The hyperfunctioning metastases of DTC generally are well differentiated, displaying excellent 99m Tc-pertechnetate and 131 I uptake (Chantadisai & Kingpetch 2014). As we have demonstrated previously, 99m Tc-pertechnetate whole-body scan should be recommended for diagnoses as well as predicting the efficacy of 131 I therapy (Liu et al 2017). Figure 1 shows practical management procedures of a representative case with hyperfunctioning DTC metastases.…”

Clinical Significance of Extra-Thyroid99mTc-Pertechnetate Uptake Before Initial Radioiodine Therapy For Differentiated Thyroid Carcinoma

“…99m Tc-pertechnetatescanning is commonly used todetect any thyroid remnants following thyroidectomy, and may provide bene cial data on the extent of remnant tissue without the need for 131 I or 123 I.The 99m Tc-pertechnetate uptake of the thyroid bed can be used as a marker of thyroid remnants, and negative uptake does not indicate the absence of thyroid remnants, suggesting a small volume. Over the last few decades,extra-thyroid 99m Tc-pertechnetate uptake has rarely been reported [10,11,3]. Furthermore, almost all available literature includes case reports [14,5,9,8,2], most of which con rm DTC metastases.…”