Imaging papillary thyroid cancer brain metastases using FDG-PET/CT

Learning Objectives 1. Recognize that brain metastases occur infrequently in patients with papillary thyroid carcinoma, but are not uncommon in patients with metastatic papillary thyroid carcinoma who develop new sites of disease. 2. Describe the appearance of papillary thyroid carcinoma brain metastases on FDG-PET/CT. 3. Discuss the value of FDG-PET for detecting brain metastases in general and the potential role it may play in detecting brain metastases from papillary thyroid carcinoma.

The overall incidence of brain metastases from papillary thyroid cancer is low; however, the brain is a major site for subsequent metastases in patients with metastatic papillary thyroid carcinoma who develop new sites of disease. FDG-PET generally is not useful detecting brain metastases, which often are small and may be obscured by the high FDG uptake of normal cortical gray matter, and there are few data on its role in the detection of metastatic thyroid carcinoma to the brain. We present 2 cases in which brain metastases from papillary thyroid carcinoma were readily detected using FDG-PET/CT. Methods: (1) Retrospective data review. (2) Compare PET/CT scan findings in 2 patients with papillary thyroid carcinoma metastatic to the brain with correlative clinical data including but not limited to contemporaneous MRI scans, I-131 scans and brain biopsy results. Conclusion: Our study demonstrated high avidity of papillary thyroid carcinoma brain metastases for FDG and therefore, consideration should be given to including the entire brain in FDG-PET/CT studies performed on patients with papillary thyroid cancer