Tumours associated with the carcinoid syndrome, VIPomas, glucagonomas, somatostatinomas and nonfunctioning tumours are usually greater than 2cm in diameter, and over fifty per cent will have metastasised at the time of diagnosis. Localisation of these tumours and their metastases is easily accomplished with ultrasonography and computed tomography (CT) scanning.
Forty percent of gastrinomas, however, are less than 1cm in diameter, and localisation of these tumours and other microadenomas is best achieved with a combination of ultrasonography, rapid and dynamic CT scanning following a bolus injection of contrast, and highly selective visceral angiography, which will identify some seventy per cent of cases.
