Positron Emission Tomography (PET) is a type of nuclear medicine imaging technique that uses radioactive tracers to visualize the functioning of organs in real time. PET scanner emits positrons, which are particles that interact with tissues and produce gamma rays. These gamma rays detected by the PET scanner, creates images that show the metabolic activity of cells. PET scans diagnoses conditions like cancer, heart disease, and brain disorders. They are particularly effective at showing areas of increased metabolic activity. A PET-CT scan combines the principles of both PET and CT scans.
PET scanner and a CT scanner when used together in a single machine, it allows for the fusion of functional (metabolic) and structural (anatomical) information. The PET-CT scan provides detailed images of both the body’s internal structures and the metabolic activity of cells and may provide a more accurate diagnosis than the two scans performed separately. This is especially useful for cancer staging, as it can help pinpoint the exact location of abnormal metabolic activity within the body.
How does a PET/CT work?
Before undergoing a PET/CT scan, you’ll receive an injection of a small amount of radioactive sugar called fluorodeoxyglucose-18 (also known as FGD-18 or tracer). Cells in your body naturally absorb sugar, and areas with higher energy consumption, such as cancer cells, absorb more of this radioactive sugar. The PET scan then visualizes where this radioactive tracer accumulates in your body.
During the CT scan, X-ray images from different angles are captured.Sometimes, healthcare professionals inject a dye before administering X-rays to highlight certain details. Subsequently, a computer combines the PET and CT images. This fusion produces a detailed 3D representation that highlights any anomalies, including tumors. This combined information helps doctors gain a comprehensive understanding of a condition.
Role of PET/CT in cancer treatment
A CT scan captures detailed images of your body’s organs and tissues. Meanwhile, a PET scan excels in detecting unusual activity. Doctors rely on PET-CT scans to gather extra insights about cancer. Apart from determining the cancer stage, a PET-CT scan assists doctors in
- Identifying the most suitable spot for a biopsy.
- Evaluating the effectiveness of ongoing cancer treatment.
- Check for any fresh cancer growth once treatment concludes.
- Strategizing radiation therapy plans.
Ideal Choice
The choice between a PET scan and a PET-CT scan depends on the specific diagnostic needs. PET scans are suitable when the focus is primarily on identifying metabolic activity and pinpointing areas of abnormal cell function. PET-CT scans make it more ideal when both anatomical and metabolic information is needed. This makes it particularly valuable for cancer staging and treatment planning.
In essence, the decision between a PET scan and a PET- CT scan is based on the clinical context and the information required by the doctor to make an accurate diagnosis and develop an appropriate treatment plan.