PET scans are an essential method of imaging in modern healthcare because they offer precise visualisations of the cellular operations of tissues and organs. PET scans are used in many different medical fields, including neurology, cardiology, and oncology.
They are often combined with other imaging techniques to provide a better understanding of diseases. The following article explores the many PET scan types, their purposes, the process, and how to analyse the results.
What is a PET Scan?
A medical imaging method called Positron Emission Tomography (PET) scan offers comprehensive information about the body’s metabolic and functional processes. It involves injecting a tiny amount of radioactive tracer into the body, usually connected to glucose. Areas with higher metabolic activity, such as cancer cells, absorb more of the tracer, allowing the PET scanner to produce 3D images that highlight abnormal activity.
PET scans provide essential information on the structure and functioning of tissues and organs. They are frequently used to identify cancer, evaluate heart health, and diagnose neurological conditions, including epilepsy and Alzheimer’s disease.
Types of PET Scans
PET scans can be classified based on the type of radiotracer used and the medical condition being investigated. Some of the primary types of PET scans include:
FDG-PET (Fluorodeoxyglucose PET)
Fluorodeoxyglucose (FDG), a glucose analogue, is used in the most common type of PET scan to track the body’s metabolic activities. Cancer is often identified using FDG-PET scans because malignant cells have higher glucose intake and metabolic rates. It can also be used to diagnose neurological conditions, including epilepsy and memory loss. FDG-PET can also monitor treatment responses by showing changes in metabolic activity after therapy.
Amyloid PET Scan
This kind of PET scan can detect amyloid plaques, which are linked to Alzheimer’s disease. Doctors can defuse a specialised tracer that attaches to amyloid particles in the brain to determine whether a patient has Alzheimer’s disease or another form of dementia. The scan also helps differentiate between different types of cognitive decline in patients.
Cardiac PET Scan
Cardiac PET scans assess cardiac blood flow and identify regions of anaemia or damaged heart tissue using various radiotracers, such as nitrogen-13 ammonia or rubidium-82. This type of PET scan greatly benefits diagnoses of coronary artery disease and appraisals of myocardial viability. It also helps forecast a patient’s chances of recovering from treatments like bypass surgery or angioplasty.
Dopamine PET Scan
Dopamine PET scans are used primarily in the field of neurology to evaluate dopamine receptors in the brain. This type of scan is often employed to diagnose and monitor neurodegenerative diseases like Parkinson’s disease, where dopamine levels are significantly affected. Psychological disorders like addiction and schizophrenia are also examined with dopamine PET scans.
Purpose of PET Scans
PET scans can be used for a variety of medical applications, depending on the condition or disease being addressed:
Cancer Detection and Monitoring
PET scans play a key role in the diagnosis and staging of malignancies, including lymphoma, lung, breast, and colon. By measuring how much glucose cancer cells consume, PET scans help identify tumours, assess whether they have spread, and monitor the effectiveness of treatments like chemotherapy.
PET scans are also helpful in distinguishing between scar tissue from post-treatment cancer and active malignancy. By identifying the precise location of cancerous tissues, they can help plan radiation therapy.
Heart Disease Evaluation
PET scans are used in cardiology to measure cardiac tissue viability, diagnose coronary artery disease, and check blood flow. This scan allows cardiologists to identify which areas of the heart are affected by heart attacks or other cardiac disorders and which are still functional.
PET scans can also be used to evaluate the efficacy of medical interventions such as angioplasty or bypass surgery by monitoring improvements in heart and blood flow.
Neurological Disorders
PET scans are essential in neurology for the diagnosis and ongoing observation of diseases such as Parkinson’s, epilepsy, and Alzheimer’s. By using PET scans, doctors can customise the parts of the brain affected by these disorders and customise treatment approaches. PET scans can also identify aberrant metabolic activity in the brain.
They are also used to identify brain tumours and investigate the brain’s workings, helping to create new treatments for neurological diseases.
Infection and Inflammation
PET scans can also detect areas of infection or inflammation in the body. It can be particularly useful for identifying sites of chronic inflammation, such as that in autoimmune diseases, or localising infections when other imaging techniques are inconclusive. PET scans are also helpful in evaluating the spread of infections in the body, such as in events of fever of unknown origin or tracking inflammatory conditions like sarcoidosis.
PET Scan Procedure
The following describes the process for a PET scan, including all the necessary procedures from planning to aftercare:
1. Preparation
Patients are usually advised to fast for four to six hours before a PET scan to guarantee that their blood glucose levels are low, as high blood glucose can compromise the accuracy of the results. Also, patients should refrain from intense physical activity prior to the scan because this could enhance the muscles’ absorption of glucose and provide false positive results.
Patients should notify their doctor in advance if they are taking any particular medications or if they have any allergies, especially to contrast materials or radiotracers. Before the scan, diabetic individuals may get specific advice on how to take insulin and manage their blood sugar.
2. Tracer Injection
A small amount of radioactive tracer is injected into the patient’s bloodstream. The type of tracer used depends on the specific PET scan being conducted. For example, FDG is used for cancer and brain disorders, while other tracers might be used for heart or neurological scans.
Patients usually wait 30 to 60 minutes following the injection to give the tracer time to move throughout the body and build up in the targeted tissues.
3. Scanning Process
Once the tracer has circulated, the patient lies on a table that glides inside the PET scanner, a sizable, doughnut-shaped device. The scan itself usually lasts 20 to 60 minutes, during which the patient must remain as still as possible to prevent motion artefacts from affecting the image quality.
The PET scanner identifies the radiation emitted by the tracer as it decays, creating detailed images of the body’s metabolic activity. The entire procedure is painless, although patients may experience slight discomfort from lying still for an extended period.
4. Post-Scan
Patients can immediately go back to their everyday lives after the scan. In a few hours, the radiotracer normally exits the body through the stools and urine. Drinking a lot of water is usually advised to help flush the tracer out more rapidly.
Conclusion
In conclusion, PET scans are essential for the diagnosis and treatment of many disorders because they provide information about the composition and functionality of tissues and organs. PET scans provide helpful information that helps with treatment decisions, whether they are used to diagnose neurological problems, assess heart disease, or detect cancer. Patients, as well as doctors, can more easily navigate the arduousness of medical diagnosis and treatment planning when they are aware of the types, purposes, procedures, and outcomes of PET scans.
