Читать книгу Essential Endocrinology and Diabetes - Richard I. G. Holt - Страница 103

Positron emission tomography (PET) is a form of functional imaging which is widely used to assess metabolism in neoplasia and allows the identification of tumours that may be overlooked by conventional imaging. Cancer cells often have accelerated glucose metabolism and more readily take up glucose than surrounding healthy cells. This process can be visualized by using the radiotracer is 2‐[18F] fluoro‐2‐deoxyglucose [(¹⁸F)‐FDG] which crosses the cell membrane and is phosphorylated to become FDG‐6‐phosphate. This is resistant to further metabolic processes and can be imaged. When the kinetic energy of [(¹⁸F)‐FDG] is dispersed as a positron, this particle travels a short distance and interacts with an electron to release two photons which can be detected by a pair of detectors located on opposite sides of the patient. PET images are obtained simultaneously with CT images to match metabolic changes to specific anatomy.

A number of hormone precursors and amino acids are labelled with ¹¹C and used successfully in the management of parathyroid, adrenal and pituitary tumours but the short‐life of these tracers have limited the clinical application. Newer tracers with longer half‐lives, such as Gallium‐68, are now being applied to neuroendocrine tumours, including phaeochromocytoma.