Avid thallium-201 uptake in hepatic carcinoid metastases

While radiolabelled somatostatin analogues sensitively detect extrahepatic carcinoid tumour, intrahepatic metastases are frequently not visualised due to somatostatin accumulation in normal hepatic tissues. We report a case of avid thallium-201 uptake in multiple hepatic carcinoid metastases using single-photon emission tomography (SPET) and compare this to a SPET technetium-99m sulphur colloid scan in the same patient. The 99mTc sulphur colloid images demonstrate multiple focal defects at the site of known metastases in the hepatic right lobe (confirmed on both CT and surgery). However, there is avid uptake of thallium in the metastases on comparative SPET slices. 201Tl may be a useful agent for the detection and localisation of carcinoid tumour and in particular of intrahepatic carcinoid metastases.