Gallbladder Visualization on I-131 Post-Ablative Whole Body Imaging Mimicking Hepatic Metastases

A 52-year-old woman with follicular thyroid carcinoma presented for ablative radioiodide and whole body I-131 imaging following subtotal thyroidectomy. An abnormal focus of increased activity was present in the region of the gallbladder fossa, persistent on delayed imaging. Subsequent CT revealed no hepatic metastases. Contemporaneously, the patient described right upper quadrant abdominal pain. Abdominal ultrasound demonstrated cholelithiasis. Cholecystectomy revealed extensive cholelithiasis and evidence of chronic cholecystitis; no hepatic metastases were identified. This case demonstrates the potential pitfall of gallbladder activity on I-131 whole body imaging secondary to cholecystitis mimicking hepatic metastases.