PET–CT

Positron emission tomography–computed tomography (better known as PET–CT or PET/CT) is a nuclear medicine technique which combines, in a single gantry, a positron emission tomography (PET) and a computed tomography (CT) scanner, to acquire sequential images from both devices in the same session. The combination of image data are then integrated into a single superposed (co-registered) image that aligns anatomical structures from both imaging modalities into one. Thus, functional imaging obtained by PET, which depicts the spatial distribution of metabolic or biochemical activity in the body can be more precisely aligned or correlated with anatomic imaging obtained by CT scanning. Two- and three-dimensional image reconstruction may be rendered as a function of a common software and control system. PET–CT has revolutionized medical diagnosis in many fields by integrating the ability to improve quality in locating metabolically active regions to functional projection imaging such as CT. For example, many diagnostic imaging procedures in oncology, surgical planning, radiation therapy and cancer staging have been changing rapidly under the influence of PET–CT availability. Clinical sites that have been gradually substituting conventional PET devices with PET–CT systems have seen enhanced performance from the recently integrated imaging systems. The PET-CT system has the advantage of providing both functions of Positron emission tomography in three dimensions and Computed tomography in two dimensions to create high-quality, full-body diagnostic images. The integration of both modalities provide examinations that produce essential information like tumor localizations, volume size, and quantified metabolic activity levels. A disadvantage surrounding the use of the PET/PET–CT imaging systems is the difficulty in radiopharmaceuticals production and transportation. Radiopharmaceuticals, also known as radiotracers, have very a short half-life which makes production and transportation bound to extremely short distances from the imaging location. The production requires a very intricate cyclotron as well as a production line for the radiopharmaceuticals and at least one PET–CT radiopharmaceutical is made on site from a generator: Ga-68 from a gallium-68 generator. For example, one of the industry's most commonly used radiotracers fluorodeoxyglucose (18F-FDG) works by tracing glucose metabolic activity within the body and holds a half-life of approximately 120 minutes. Benefits of PET–CT By diagnosing with the help of a PET–CT, the advantages of the two individual methods are combined, and the result considerably exceeds images obtained by the two devices taken separately. The method allows identification of all cancerous formations in the body, regardless of their size or degree of development. The diagnosis time is short, the doctor can thus save precious time in the fight with the disease The substance used, although it is radioactive, presents a very low degree of risk, it is naturally eliminated by the body within a maximum of 24 hours after administration PET–MRI, like PET–CT, combines modalities to produce co-registered images.