Coexistant Iodine-Negative Pleural Metastasis With Iodine-Positive Lung and Bone Metastases in a Patient With Differentiated Thyroid Cancer

99mTc-pertechnetate-avid metastases from differentiated thyroid cancer are prone to benefit from 131I therapy: A prospective observational study

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

Rare renal metastases from differentiated thyroid carcinoma: early clinical detection and treatment based on radioiodine

OBJECTIVE

The aim of this study was to explore the clinical characteristics of renal metastatic cancer, the methods for its detection by radioiodine (131)I, and the response to (131)I treatment in fourteen patients with renal metastases from differentiated thyroid carcinoma (DTC).

SUBJECTS AND METHODS

DTC patients (n = 2,955) that received treatment with (131)I were retrospectively analyzed. Scans ((131)I-WBS, (31)I-SPECT/CT and/or (18)F-FDG-PET/CT) were performed after an oral therapeutic dose of (131)I. Therapeutic efficacy was evaluated based on changes in Tg and anatomical imaging changes at renal lesions.

RESULTS

Among these 14 patients, 11 had avidity for (131)I, but three patients did not accumulate (131)I after (131)I treatment. In the 11 (131)I-positive renal lesions, 10 cases were detected by (131)I-SPECT/CT combined with another imaging modality and one case by (131)I-WBS combined with ultrasonography (US). In the three (131)I-negative renal lesions, two cases were detected by 18F-FDG-PET/CT and one case by computed tomography (CT). In 11 patients with (131)I-avid renal metastases, Serum Tg levels in 81.82% (9/11) patients showed a gradual decline, and 18.18% (2/11) of the patients showed a significant elevation. There was no marked difference in serum Tg before the last (131)I treatment (Z = 0.157; p = 0.875). Only one patient presented partial response, eight patients exhibited stable disease, and renal metastases progressed in two patients showing progressive disease. No patients reached complete response.

CONCLUSION

(131)I-SPECT/CT, combined with another imaging modality after (131)I-WBS, can contribute to the early detection of renal metastases of DTC. (131)I therapy is a feasible and effective treatment for most DTC renal metastases with avidity for (131)I.