The localization of endocrine tumours using radionuclide scanning and sampling techniques

In the diagnosis of patients with functioning endocrine tumours, clinicians are frequently confronted with difficulties in detecting small benign tumours, or in determining the extent of metastatic spread. Routine investigations in these patients include non-invasive radiological techniques, ultrasound, computed tomography and magnetic resonance imaging. Radionuclide scanning provides metabolic information, thereby allowing localization of the tumour(s) or metastases during a safe screening of the entire body, despite the lack of anatomical detail. A more specific technique, peptide receptor scintigraphy, may be used to select patients for treatment with peptide analogs, or radiotherapy with a receptor analog labelled with a radionuclide. Sophisticated hormone level sampling techniques provide site-specific information and may assist in localization of the functional tumour. This paper reviews the application of sampling techniques and radionuclide scintigraphy, and their efficacy in localizing small primary tumours and metastatic disease.