[Medical Q&A] Why do some lung cancer patients need PET-CT?

Planner: Chinese Medical Association

Reviewer: Zhou Xin, Chief Physician, First People's Hospital, Shanghai Jiao Tong University School of Medicine

PET-CT is a relatively unfamiliar examination for many people, but it has important application value in the diagnosis, staging, treatment, evaluation and follow-up of lung cancer.

During a PET (positron emission tomography) examination, the examiner will inject a drug into the patient's body. This drug contains the metabolite glucose and radioactive isotopes, and the drug can be distributed throughout the body through blood circulation. Because malignant tumors proliferate rapidly and consume a lot of glucose, the radioactive drug containing glucose will be taken up by tumor cells, and the places where it gathers can also be detected and imaged by instruments. PET examination can distinguish normal tissue from diseased tissue, but the detailed anatomical structure and location of tumor cells still need to be provided by CT (computed tomography) examination, because CT examination has high spatial resolution and can clearly display tiny anatomical structures. PET-CT combines these two examination methods, performs synchronous scanning on the same machine, and fuses PET images and CT images together to generate a comprehensive three-dimensional image, which helps doctors locate and diagnose more accurately, and helps guide subsequent more targeted treatment. For nodules that are difficult to identify with other imaging examinations, PET-CT examination can help distinguish between benign and malignant. In addition, PET-CT performs a whole-body scan and can also evaluate whether the tumor has spread to other parts of the body, such as mediastinal lymph nodes, liver, bones, etc. In conclusion, PET-CT examination is of great significance and plays an important role in the diagnosis, treatment and management of lung cancer patients.