PET-CT is an important diagnostic and prognostic tool in cancer treatment. From diagnosis to staging, from monitoring to evaluating a patient’s treatment response, PET-CT plays a pivotal role in all major phases of the cancer journey.
PET-CT (Positron Emission Tomography/Computed Tomography) is a nuclear medicine imaging method that combines the structural information from the CT scan along with the metabolic activity information from the PET scan for better diagnostic support.
The data from PET and CT imaging are combined for two or three-dimensional image reconstruction with the help of a software system. These combined scans help oncologists in pinpointing anomalies and devising the best treatment plan for various cancers and other diseases.
How Does PET-CT Work?
Before the scan, the radiotracer is injected into the patient’s vein. A radiotracer comprises a radioactive isotope and a bio-molecule such as glucose. Later, the patient will be made to wait for 45 – 60 minutes for it to be absorbed by the body cells.
Once the radiotracer is injected, it reaches those regions in the body that utilise glucose.
Tumour cells, for instance, absorb more glucose as they need the energy to dividerapidly. During the imaging, we will be tracking the radioactive emissions by the radioactive isotope that is tagged with glucose. Those areas with increased glucose or radiotracer absorption appear as bright spots.
A special camera is used to detect these radioactive emissions and produce images of the metabolic activity of the scanned region. A CT scan that is carried out simultaneously captures the X-ray images of internal organs from different angles.
A computer then combines the data from PET and CT scans to produce 3-dimensional images of internal organs. Any abnormalities like tumours can be easily and accurately detected through a PET-CT scan.
Advantages of PET-CT Imaging
PET-CT imaging has numerous advantages:
- Through enhanced accuracy, PET-CT supports the right diagnosis and thereby, the right clinical decisions.
- PET-CT helps specialists detect cancers in their early stages when they can be treated with positive outcomes.
- By providing highly reliable information about the lesions or abnormal masses, PET-CT imaging helps in effective treatment planning.
- PET-CT imaging also helps assess the patient’s response to the treatment given.
- PET-CT can help prevent unnecessary invasive procedures and retests by providing helpful, comprehensive molecular and structural data at once.
- This imaging process is non-invasive and takes less time. There is no downtime or recovery required for the patients after the test.
- PET-CT imaging also plays an important role in radiotherapy planning.
Frequently Asked Questions
A radiotracer chemical is used during the imaging; however, the radiation exposure is low. It is a safe procedure. If you have any concerns about PET-CT, kindly discuss them with your doctor before the procedure.
Also, pregnant and lactating women should talk to their doctors before the procedure to understand the potential risks.
- You will be asked not to eat for about six hours before your scan.
- You will also be asked to refrain from exercising for 24 hours before the scan.
- Right before the procedure, you will be asked to remove metal objects like jewellery, eyeglasses, hairpins, dentures, etc., as these may affect the CT scan results.
- Women should always inform their doctor if they are pregnant or breastfeeding.
Eat normally and drink plenty of fluids once the procedure is complete. You should be okay after the scan and can resume normal activities right after the procedure.
FDG, which is the radiotracer injected, is similar to glucose. However, it is injected in smaller quantities, and it will not affect your blood glucose level.