PET CT – The Gold Standard For Cancer Diagnosis

07 Mar, 2022

The right diagnosis could be one of the best weapons against cancer.

Oncologists always say that the success of any cancer treatment lies in the diagnosis. Simply put - if you get the diagnosis right, you get the treatment right. Receiving the right diagnosis has become more important than ever, as the consequences of misdiagnoses are already well-known.

Cancer is diagnosed through numerous means; however, imaging is considered to be one of the most varied and accurate forms of diagnosis. In the past, oncological imaging involved MRI, endoscopy, ultrasound, CT imaging, PET imaging, etc. However, the field of cancer diagnostics is constantly evolving and moving towards combining different techniques (multimodal) to study both the molecular and physical aspects of the tumour. One such technological innovation is PET CT imaging. PET CT imaging helps oncologists arrive at more accurate diagnostics and devise treatment plans that are focused on treating the tumour without harming the healthy tissues.

What is PET CT Imaging?

PET CT (Positron Emission Tomography/Computed Tomography) is a nuclear medicine imaging technique that combines the structural information from the CT scan along with the metabolic or biochemical activity information from the PET scan.

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 abnormal metabolic activity and devising the best treatment plan for various cancers. Also, PET CT may provide a more accurate diagnosis when compared to the diagnosis obtained from PET or CT alone.

PET CT imaging helps in staging, treatment planning, treatment monitoring, restaging and recurrence evaluation.

How Does PET CT Work?

PET CT imaging is a non-invasive and painless procedure. This testing method uses radiolabelled molecules known as ‘radiotracers’ or ‘radiopharmaceuticals’ in small quantities. These radiotracers will be used to detect or study abnormal cellular activity throughout the body. Fluorodeoxyglucose (18F), which is a radioactive form of glucose, is a commonly used radiotracer during PET CT imaging. This radiotracer will be injected into the body before the scanning.

Cells need glucose for energy. Cancer cells, due to their higher metabolic activity, need more glucose. This increased glucose absorption can be tracked during the imaging as the radiotracer starts emitting radiation. Those areas with increased glucose 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.

How Does PET CT Imaging Help Doctors (and Patients)?

PET CT scanning helps both the patients and the doctors in numerous ways:

  • 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 successfully.
  • 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 by providing helpful 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.

Frequently Asked Questions on PET CT Imaging

1. How long does the procedure take?

The entire procedure may take up to 60 to 90 minutes. The radiotracer that is injected into the vein takes nearly an hour to travel throughout the body and get absorbed by the tissues. The imaging takes around 30 minutes.

2. Is there a hospital admission required for a PET CT scan?

No, you don’t need a hospital admission for your PET CT scan. However, there will special instructions provided by your doctor, pertaining to your food and water intake before your scan – this has to be followed without fail. This is an outpatient procedure. You can get back to your daily activities almost immediately after the procedure.

3. Is PET CT imaging safe? Are there any side effects?

PET CT imaging is a safe, non-invasive and painless procedure. There are no major side effects associated with the scan. However, a few patients may experience mild discomfort, which wears off with time. If it concerns you, you can talk to your doctor.

4. When will I get my PET CT results?

The PET CT results will be available in 24-48 hours.

5. Can a PET CT scan worsen my claustrophobia?

The scan happens in a confined chamber, and it is normal for claustrophobic patients to get stressed. If you are claustrophobic, please talk to your doctor, who will help you with medications that’ll keep you relaxed during the procedure. Apart from this, there are few more things that you can do to reduce your anxiety, such as listening to music, covering your eyes, focusing on breathing, following a distraction technique like counting, etc.

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