Utility of 99mTcO4- static imaging for detecting metastatic lesions in differentiated thyroid cancer

The aim of this study was to evaluate the utility of thyroid static imaging with 99mTcO4- for detecting metastatic lesions following surgery in patients with Differentiated Thyroid Cancer (DTC). A total of 420 consecutive post-total thyroidectomy patients with pathologically diagnosed differentiated thyroid cancer underwent thyroid static imaging with 99mTcO4- before 131I treatment to evaluate the size, location, and function of the residual thyroid. They also underwent 131I whole-body scanning (131IWBS), as well as single-photon emission computed tomography/computed tomography fusion imaging (when necessary), for evaluation of the lesions. The detection rates of thyroid static imaging with 99mTcO4- and 131I-WBS (therapeutic dose) were 83.81% and 98.33%, respectively. The sensitivity of 99mTcO4-  thyroid static imaging was 85.2%, and the rate of detection with both 99mTcO4- static imaging and 131I-WBS was 85.48%. The use of 99mTcO4- thyroid static imaging identified metastatic lesions in 10 patients; thus, the original planned treatment dose and protocol were adjusted in these patients. Based on our findings, we conclude that thyroid static imaging with 99mTcO4- can be used to evaluate the residual thyroid tissue after thyroid carcinoma resection and can identify metastatic lesions, thereby helping to guide the selection of the 131I treatment dose.