99mTc-MDP SPECT-CT and Ultrasound in the Diagnosis and Staging of Thyroid Metastasis From Osteosarcoma.

The classification of thyroid nodules in children is often difficult, especially in pretreated patients with metastatic disease. In osteosarcoma patients, Tc-MDP SPECT/CT is used for primary and follow-up staging. Bone and soft tissue metastases can be revealed because of Tc-MDP imaging of osteoid-producing metastases. We present Tc-MDP SPECT-CT, CT, and ultrasound images of a highly suspicious calcified thyroid lesion in a 17-year-old boy with osteosarcoma. High uptake in Tc-MDP SPECT-CT provides diagnosis of thyroid metastasis of osteosarcoma, which was proven by histopathology.