From the Guidelines
PET/CT is a medical imaging technique that combines positron emission tomography (PET) and computed tomography (CT) to provide detailed information about the structure and function of tissues and organs in the body. It merges PET, which uses a radioactive tracer to show metabolic activity in cells, with CT, which provides detailed anatomical images. During a PET/CT scan, patients receive an injection of a radioactive sugar solution (typically 18F-fluorodeoxyglucose or FDG) that is absorbed by cells with high metabolic activity, such as cancer cells. The PET scanner detects the radiation emitted by this tracer, while the CT scanner simultaneously creates cross-sectional images of the body's structures. This combination allows physicians to precisely locate areas of abnormal metabolic activity within specific anatomical structures.
The key advantages of PET/CT include:
- Increased accuracy and certainty of locating lesions 1
- Reduced time of acquisition and final diagnosis 1
- Improved staging and restaging accuracy 1
- Ability to differentiate physiological from pathological foci 1
PET/CT is particularly valuable in:
- Cancer diagnosis, staging, and treatment monitoring 1
- Evaluating certain neurological disorders and cardiac conditions 1
- Providing more information than PET alone or CT alone in the overall staging of non-small-cell lung cancer 1
The procedure typically takes 2-3 hours, including preparation time, and patients usually need to fast for 4-6 hours beforehand to ensure accurate results. The use of PET/CT can change the patient's management and improve patient outcomes 1. According to the most recent and highest quality study, PET/CT is a powerful tool that can display and quantify molecular processes in the entire body in a single noninvasive examination 1.
From the Research
Definition of PET/CT
- PET/CT (Positron Emission Tomography/Computed Tomography) is a medical imaging modality that combines the strengths of PET and CT scans to provide detailed information about the metabolic activity and anatomy of the body 2, 3, 4.
- PET scans use positron-emitting biomarkers to detect changes in cellular activity, while CT scans provide detailed anatomical information 2, 3.
Principles of PET/CT
- The combination of PET and CT allows for the accurate registration of metabolic and molecular aspects of disease with anatomical findings, adding valuable information to the diagnosis and staging of tumors 3.
- PET/CT scanners use a CT examination for attenuation correction of PET images, reducing examination time and improving image quality 3, 4.
Applications of PET/CT
- PET/CT is widely used in oncology for staging and restaging of various cancers, including colorectal cancer, lung cancer, breast cancer, head and neck cancer, and lymphoma 2, 5, 6.
- It is also used for monitoring response to therapy and detecting recurrence in asymptomatic patients with rising tumor marker levels 5, 6.
- PET/CT has been shown to change the course of management in approximately 27% of patients 5.
Advantages of PET/CT
- PET/CT offers several advantages over PET alone, including the ability to accurately localize increased FDG activity to specific normal or abnormal anatomic locations 4.
- It provides a unique combination of cross-sectional anatomic information and metabolic information, acquired during a single examination and fused 4.
- PET/CT is an efficient tool for whole-body staging and re-staging within one imaging modality 2, 6.