Figure 2.

¹³¹I-avid PTC metastatic pulmonary lesions accumulating ^99mTc-pertechnetate. A 50-year-old female patient with PTC presented with suspected metastatic disease in the lungs 1 month after total thyroidectomy with ssTg of 500.0 ng/mL and TSH of 77.45 mU/L. ^99mTc-pertechnetate SPECT/CT (A; arrow) and planar image (D) before ¹³¹I therapy showed pulmonary nodules with obviously increased ^99mTc-pertechnetate uptake. ¹³¹I SPECT/CT (B; arrowhead) and planar image (E) 5 days after the initial administration of 7.4 MBq (200 mCi) ¹³¹I correspondingly showed the pulmonary nodules with increased ¹³¹I accumulation. Six months later, ssTg decreased to 13.78 ng/mL with TSH of 37 mU/L just before the second course of ¹³¹I administration (7.4 MBq, 200 mCi), and the pulmonary nodules were not found on ¹³¹I SPECT/CT (C) and planar image (F). PTC = papillary thyroid carcinoma.