The heavyweight weapon of nuclear medicine department: pet-ct examination As an important auxiliary department of the hospital, many patients are not very familiar with it. PET-CT, the most advanced positron emission computed tomography and advanced high-resolution multi-row spiral CT, is a large functional metabolic and molecular imaging diagnostic device that combines the two strengths of PET and CT at the same time, achieving the true sense of complementary advantages (1+1>2). PET-CT is an epoch-making milestone in the history of medical imaging diagnostic technology, as it provides accurate information on anatomical structure and functional and metabolic changes of lesions (e.g. malignant tumors) at the same time, significantly improving the accuracy of disease diagnosis. At the same time, PET-CT is one of the most important high technologies in the international life science (brain function, gene protein function imaging diagnosis) research and its clinical application. Q: What are the advantages of PET-CT technology? A: Medical imaging modes can be broadly divided into two categories: anatomical imaging and functional imaging, the former mainly describes human anatomy and morphological change information, represented by X-ray radiography; the latter mainly describes human functional metabolism and molecular abnormality information, represented by nuclear medicine imaging, both have different characteristics. In contrast, nuclear medicine imaging detects the extremely weak signal changes emitted by the imaging drugs injected into the human body, known as disease “probes”, as imaging parameters, and the resulting images focus on reflecting the function of internal organs, metabolism and other physiological and biochemical processes. PET-CT combines the most advanced human function and metabolism imaging technology with the diagnostic radiological imaging technology of multi-row spiral CT, using the same examination bed and the same image processing workstation, with the dual examination function of PET and multi-row CT, providing precise anatomical structure and functional and metabolic changes of lesions (such as malignant tumors) at the same time in one examination. The diagnostic accuracy of PET-CT is significantly better than that of PET alone or multi-row CT alone, which is an epoch-making milestone in the history of medical imaging diagnostic technology today. Q: What are the characteristics of molecular diagnostic imaging technology for nuclear medicine tumor? A: After entering the 21st century, medicine has entered the era of “molecular medicine”. The understanding of diseases must be deepened from isolated organs and systems to the cellular molecular level of physiology and biochemistry, providing information on the cellular molecular level of disease changes and clarifying the metabolic activity of diseased tissues to help diagnosis, treatment and efficacy evaluation. Since tumor tissues are rich in blood supply, enhanced metabolism and increased energy consumption, nuclear medicine examination often uses molecular “probes” to understand the active degree of tumor metabolism in terms of sugar, fat and protein, which is of high clinical value for the differential diagnosis of benign and malignant tumors, tumor grading, metastasis detection, efficacy observation, differential diagnosis of necrosis caused by radiation therapy and chemotherapy and tumor recurrence, and helps in the proper management and prognosis of tumor patients. Therefore, nuclear medicine PET and PET-CT technologies are the best means of clinical tumor molecular imaging diagnostic technology at present. Q: What problems can PET and PET-CT solve for tumor patients? A: (1) Identification of benign and malignant tumors or lesions: As we all know, identification of benign and malignant tumors is very important, which not only relates to the treatment plan, but also directly affects the prognosis of patients. If a patient has a single nodule in the lung, after PET/CT examination, if the metabolic activity of the nodule is not high, it indicates a high possibility of benign lesion, and the choice of surgery should be cautious; on the contrary, if the metabolic activity of the nodule is high, it indicates a possibility of malignancy, and active treatment measures, including surgery, should be taken. (2) Tumor staging: tumor staging is an important basis for deciding the treatment plan of patients. one PET/CT whole body imaging can provide information on the presence or absence of metastases in various organs of the body, such as brain, lung, lymph nodes, liver, adrenal glands and bones, which is helpful for accurate clinical staging of various tumors, such as lung cancer, breast cancer, colon cancer, ovarian cancer and lymphoma. Taking the diagnosis of lymph node metastasis as an example, PET/CT is more accurate because CT or MRI is to consider enlarged lymph nodes (>25px) as metastases, which are not infrequently enlarged due to chronic inflammation or misjudge normal-sized lymph nodes that have been invaded by tumor tissues as normal, while PET is more accurate than considering only the lesion size to determine whether the lymph nodes are metastatic based on their metabolic activity. (3) Assessment of therapeutic efficacy: Because of the high sensitivity of PET/CT and its functional metabolic imaging, it is more accurate and sensitive in judging the efficacy of radiotherapy and chemotherapy, which is helpful to guide clinicians to adjust the treatment plan in time. (4) Identify necrosis, fibrosis and residual or recurrence after tumor treatment: PET/CT can identify necrosis, fibrosis and residual or recurrence after chemotherapy, radiotherapy and surgery, which is difficult to do by other imaging means. (5) Helping to formulate tumor radiotherapy plan: PET/CT can help radiotherapists to outline more reasonable biological target areas and help to formulate radiotherapy plan. (6) Searching for primary tumor foci: Patients who have clearly had tumor metastases can further search for the primary tumor foci through PET/CT examination. Q: Why do you say that PET and PET-CT examinations actually save medical costs for patients? A: Have you encountered the torture of not having CT, MRI, B-ultrasound, X-ray, biochemical examination etc. again and again in the hospital, which consumes precious time, a lot of energy and expensive medical expenses, and some people even pay the price of life …… A large number of economic studies at home and abroad have shown that PET and PET-CT examinations can significantly save medical costs if the costs and benefits of PET and PET-CT examinations are analyzed comprehensively. This is because PET-CT examinations allow for more accurate diagnosis of patients and enable them to receive timely and effective treatment, avoiding many inappropriate examinations, misdiagnoses and treatments, and as a result, medical costs are greatly saved in general. At the same time, it reduces the patient’s pain caused by inappropriate treatment and improves the quality of life. Due to the obvious advantages of PET-CT in saving medical costs, many health insurance companies in the United States and Western Europe are willing to pay for PET-CT in oncology and heart diseases, and according to the survey, PET-CT in oncology alone can save at least$200 million per year for U.S. health insurance.