Colchicine must be stopped before imaging with [18F]-methylcholine PET/CT.

Choline is an essential amino acid, which is needed for the synthesis of membrane phospholipids. The choline uptake pathway is increasingly applied for molecular imaging of proliferating tumors. We describe a patient in whom we encountered an unexpected finding when he was referred for a routine [18F]-methylcholine PET/computed tomography scan to restage his prostate carcinoma. There was only visualization of circulating [18F]-methylcholine and no active uptake in any relevant organ. Owing to this abnormal biological behavior the scan was deemed uninterpretable. On checking his comorbidity and medication, the patient was found to take colchicine on a daily basis for his gout. After discontinuation of colchicine, the biodistribution of [18F]-methylcholine normalized. We present a possible explanation for these findings, with an impact on molecular imaging of the choline pathway and possibly reaching beyond colchicine alone.