From the Guidelines
A PET-CT scan is a diagnostic imaging procedure that combines Positron Emission Tomography (PET) and Computed Tomography (CT) to provide detailed information about metabolic activity and anatomical structures in the body. This procedure involves the injection of a radioactive tracer, typically fluorodeoxyglucose (FDG), which accumulates in areas of high glucose metabolism, such as tumors, infections, and inflammatory processes 1. Before the scan, patients are required to fast for 4-6 hours, and diabetics may need special instructions to manage their blood sugar levels. After injection, patients rest for about 60 minutes to allow the tracer to circulate, and then undergo the scan, which typically takes 20-30 minutes and requires remaining still.
The PET-CT scan uses a combination of PET and CT technologies to provide both functional and anatomical information. The PET component measures the metabolic activity of cells, while the CT component provides detailed images of internal structures, allowing for accurate localization and characterization of lesions. The CT scan can be performed with or without contrast, and may involve a low-dose or diagnostic CT scan, depending on the specific clinical question and patient needs 1. The procedure is generally considered safe, with minimal radiation exposure, and the tracer typically clears the body within 24 hours.
Key aspects of the PET-CT scan include:
- Injection of a radioactive tracer, typically FDG
- Fasting for 4-6 hours before the procedure
- Resting for 60 minutes after injection to allow tracer circulation
- Scan duration of 20-30 minutes
- Combination of PET and CT technologies to provide functional and anatomical information
- Use of low-dose or diagnostic CT scan, with or without contrast
- Minimal radiation exposure and tracer clearance within 24 hours 1.
The PET-CT scan is a valuable diagnostic tool for detecting and managing various diseases, including cancer, infection, and inflammation, and its use is supported by recent guidelines and evidence-based recommendations 1.
From the Research
Overview of PET-CT
- Positron Emission Tomography-Computed Tomography (PET-CT) is a medical imaging modality that combines the metabolic and molecular information of PET with the anatomical information of CT 2, 3, 4, 5, 6.
- This combination allows for the accurate registration of metabolic and molecular aspects of disease with anatomical findings, providing valuable information for diagnosis, staging, and treatment monitoring of various diseases, particularly cancer 2, 3, 5, 6.
Components of PET-CT
- PET facilitates the evaluation of metabolic and molecular characteristics of diseases, while CT provides detailed anatomical information 2, 3, 5.
- The combination of PET and CT in a single scanner enables the acquisition of both metabolic and anatomical images in a single session, reducing examination time and improving image accuracy 2, 3.
Clinical Applications of PET-CT
- PET-CT has various clinical applications, including oncology, cardiology, neurology, and infection and inflammation imaging, with fluorine 18 fluorodeoxyglucose (FDG) being a commonly used tracer 3, 4, 6.
- In oncology, PET-CT is used for diagnosis, staging, treatment planning, and treatment monitoring, providing valuable information on tumor metabolism and anatomy 2, 3, 5, 6.
Technical Considerations
- The use of CT for attenuation correction in PET-CT scanners can reduce examination time, but metallic objects and contrast agents may lead to artifacts in PET images 2.
- Understanding the principles of PET-CT and optimal scanning techniques is essential for advantageous use of this imaging modality 5.