What is PET/CT?

What is PET/CT?
  • PET/CT is an imaging device that combines positron emission tomography and computed tomography. PET/CT revolutionized medical imaging and was named medical “invention of the year” by TIME magazine in 2000.
  • PET is a nuclear medicine method that has been used for years and gives a 3D view of physiological processes in the body. By combining the PET device with CT, it provides anatomical and physiological information to be obtained in a single session and increases the accuracy of the examination.
  • It is 2-fluoro-2-deoxy D-glucose (radio-labeled sugar molecule) known as FDG (fluorodeoxy glucose) for PET/CT examination. FDG given intravenously; It accumulates in cells with high metabolic activity, such as tumor cells, as it proliferates rapidly.
  • For PET/CT, patients must be fasting for 6 hours before the examination. Patients can take their medications other than insulin or oral antidiabetic drugs. In diabetic patients, image quality may be suboptimal due to the competition of endogenous glucose with FDG. Therefore, before the FDG injection, the blood glucose level is determined and it is generally not recommended to perform the test at blood glucose levels above 180 mg/dL. PET/CT imaging is started 1 hour after FDG is injected.
  • The vast majority of PET/CT applications are in the field of oncology. It is used in the diagnosis, staging, restaging and evaluation of response to treatment in lung cancers, lymphoma, malignant melanoma, head and neck tumors, breast cancer, colorectal cancers, esophagus and stomach tumors, gynecological cancers, mesothelioma, primary bone tumors and metastases of unknown primary.
  • With FDG PET/CT examination, it leads to a 25-60% change in the staging, which will determine the pre-surgical (if diagnosed by biopsy) and/or post-operative treatment and the treatment to be applied. This change also plays an important role in determining the treatment method to be applied to patients. For example, patients who are considered inoperable can be operated (approximately 1/3 of the change after PET/CT), or the patient should not be operated unnecessarily, etc.
  • The FDG PET/CT examination plays an important role in imaging the living cells in the remaining tissue after the treatment applied and in deciding whether to continue the treatment, as it will accumulate in the living cells.
  • Another usage area of ​​PET/CT is to determine the amount of viable but hibernated tissue after myocardial infarction. PET/CT is accepted as the gold standard in this indication.
  • PET/CT also has uses in neurology, such as detecting epileptic focus and early diagnosis of Alzheimer’s disease, in order to evaluate the chance of surgery in refractory epilepsies.