68Ga-dotatate avid medullary thyroid cancer with occult liver metastases

A 50-year-old male patient with a history of medullary thyroid cancer and extensive previous investigation including FDG PET 18 months earlier presented for a Ga-dotatate scan. A single area of abnormal uptake was identified in the right ninth rib. An MRI scan and bone scan confirmed the bony metastasis; however, the MRI of the liver demonstrated multiple liver metastases not apparent on the PET study. These remained occult despite coregistration of the MRI and PET data. The occult nature of these lesions may have been due to a similar degree of uptake in the liver and metastases.