What is petct?

PET, known as positron emission tomography PET, is an imaging device that reflects the genetic, molecular, metabolic and functional status of a disease. It is the use of positron nucleotide labeling glucose and other human metabolites as the imaging agent, through the lesion of the imaging agent uptake to reflect its metabolic changes, so as to provide clinical information on the biological metabolism of the disease. It is a new milestone in the development of today's life science and medical imaging technology.CT (Computed Tomography) is a familiar X-ray tomography technique. It can clearly obtain the anatomical structure information of the lesion, but there are limitations in diagnosing the disease only by the structural features, and it is difficult to make accurate judgment on the nature of some lesions, such as the benign or malignant nature of the tumor, and whether there is recurrence of the tumor after surgery. PET-CT integrates PET and CT in a single instrument to form a complete imaging system, called integrated PET-CT system, which allows the patient to obtain both CT anatomical images and PET functional metabolic images after rapid whole-body scanning during the examination, with the advantages of both images complementing each other. The two images complement each other, enabling doctors to understand the biological metabolic information while obtaining precise anatomical localization, so as to make a comprehensive and accurate judgment of the disease. PET utilizes positron-emitting nuclides to label physiologically necessary compounds or metabolic substrates such as glucose, fatty acids, amino acids, ligands for receptors, and water, etc., and then introduces them into the body and applies a positron scanner to obtain an in vivo chemical image. It is also called "in vivo biochemical imaging" for its ability to show the metabolic activity of organs or tissues and the function and distribution of receptors, which has been widely emphasized by clinics. It can be said that the emergence of PET makes medical imaging technology reach a brand new level, which makes it possible to non-invasive, dynamic, quantitative evaluation of physiological and biochemical changes in cellular metabolic activities of living tissues or organs in physiological state and in the process of disease, and to obtain molecular level information, which is currently unattainable by any other methods. Therefore, in developed countries, PET is widely used in clinical practice and has become the most effective means of diagnosing and guiding the treatment of the three major life-threatening diseases, namely, tumors, coronary heart disease and brain diseases. The most commonly used PET imaging agent is 18F-labeled FDG (18F-FDG fluorodeoxyglucose), a glucose analog. Application of PET/CT in tumor diseases 1.Early diagnosis and benign/malignant differentiation of tumors: One of the important characteristics of tumor tissues is their rapid growth and vigorous metabolism, especially the increased rate of glucose fermentation. Therefore, metabolic imaging is one of the most sensitive methods for early diagnosis of malignant tumors. If a single nodule is found in the lung and PET shows markedly active metabolism, it is suggestive of a malignant lesion. If there is no metabolic increase, it suggests that the possibility of benign lesions is high, and the choice of surgery should be careful. 2. Determine the staging and grading of various types of malignant tumors: PET can carry out whole-body tomographic imaging at one time, which is not possible with other imaging devices. In addition to discovering primary lesions, it can also discover whether there are metastatic lesions in all parts of the body, soft tissue organs and bones, which is very helpful for tumor staging and provides accurate sites for puncture or tissue biopsy, which assists clinicians in formulating the best treatment plan. 3. Evaluation of therapeutic effect and prognosis: Evaluate the therapeutic effect of various treatments of tumor and make prognosis judgment to guide further treatment. 4. Early identification of tumor recurrence and re-staging of tumor: PET can make early diagnosis of tumor residue or recurrence after treatment, and differentiate it from post-treatment fibrosis and necrosis, and re-stage it according to the distribution of post-treatment foci, which is difficult to be done by structural information-based imaging means such as CT and MRI. 5. Finding of primary tumor foci: Finding primary foci for unexplained metastatic tumors through rapid whole-body PET/CT scanning. 6. Radiotherapy biological target localization: help radiotherapists outline the biological target area. For example, in the case of lung cancer combined with lung atelectasis, etc., it is difficult for radiotherapists to determine the actual boundary of the tumor. PET will help to determine the extent of the metabolically active lesions, provide a more reasonable and accurate localization for radiotherapy (especially precision radiotherapy), and reduce the side effects of treatment. Myocardial survival research has become a hot topic in recent years, and it is generally believed that PET myocardial metabolic imaging is the most accurate way to determine the activity of cardiomyocytes, which is known as the "gold standard".PET imaging can help to determine and identify necrotic myocardium and reversible ischemic myocardium, which is an important guide to interventional therapy and coronary artery bypass grafting, and can significantly improve the quality of myocardial tissue. PET imaging can help to identify and differentiate necrotic myocardium from reversible ischemic myocardium, which is an important guide for interventional therapy and coronary artery bypass grafting surgery, and it can significantly improve the success rate of bypass grafting surgery, and at the same time, it can predict the recovery of cardiac function after surgery. Brain metabolic imaging can accurately understand the activity and metabolic changes of nerve cells under normal conditions and disease states, as well as the metabolism of the cerebral cortex under different physiological conditions of stimulation and thinking activities. Through PET, we can visualize the metabolic activities of the human brain and various physiological or pathological metabolic changes, and reflect them in the form of images. Specific applications: 1. epilepsy localization: accurate localization of epileptic foci in the brain, providing the basis for surgical or gamma knife resection of epileptic foci; 2. brain tumor characterization and recurrence judgment: benign and malignant characterization of brain tumors, determining the boundary of malignant gliomas, identifying radioactive necrosis and recurrence of tumors after tumor treatment, and selecting the site of tumor biopsies. 3. early diagnosis of dementia: early diagnosis and staging of senile dementia and differentiation from other types of dementia such as vascular dementia. 4. Brain receptor research: brain receptor analysis of Parkinson's disease, diagnosis and treatment guidance. 5. Cerebrovascular disease: PET can sensitively capture the cerebral metabolic changes caused by ischemic attack, so it can be used for early diagnosis and localization of transient ischemic attack (TIA) and cerebral infarction, as well as efficacy assessment and prognosis judgment. 6. Pharmaceutical research: conduct pharmacological evaluation of neuropsychotropic drugs and guide the use of drugs, observe the changes of cerebral glucose metabolism in patients with obsessive-compulsive disorder (OCD), etc., and provide the basis for stereotactic surgical treatments before the operation and the efficacy of follow-up after the operation. PET/CT is a highly sensitive, accurate and non-invasive means of examination, which has the value of early detection and early diagnosis of many diseases (especially common malignant tumors, etc.) PET/CT examination can be a one-time whole-body imaging, which is convenient to find out whether there are any dangerous tiny lesions in the whole body, and early diagnosis can enable the examinee to get early treatment and strive to achieve a cure. At the same time, PET/CT examination is also particularly suitable for determining whether there is early ischemia, hypoxia and other metabolic function abnormalities in the brain or heart, which can help guide the examinee to take timely targeted treatment or take appropriate preventive measures.