INFORMATION FOR PATIENTS

I have an appointment for PET scan. What preparation is necessary?

•Bring - Please bring all your previous medical records and investigation reports. 

•Comfort – PET CT scans are completely painless with no side effects.

•Clothing – Dress comfortably and warmly, as the scanner room is cold. You may need to change to hospital clothes if your dress has metal clips or fittings. All metal objects are to be removed.

•Food and drinks – Generally you should limit the amount of sugar and caffeine on the day before the scan and remain fasting except water for approximately 6 hours prior to the scan.

•Rest – Avoid strenuous exertion approximately 12 hours prior to the study.

•Medications – You may take your scheduled medications prior to arriving for your scan, if they can be tolerated on empty stomach. Please bring all the medications.

•Diabetic – Please consult us for specific instruction regarding insulin and medication.

What is the procedure for PET-CT?

Please remain fasting for 6 hours before the procedure. Only water is allowed during this period. You will be called 1 hour prior to the start of the study. Upon arriving at the PET–CT center report to the receptionist. After noting your clinical details you will receive an injection of radioactive glucose (FDG), which will take approximately 60 minutes to distribute throughout your body. Post injection you will be asked to take approximately 2 litres of water. You will have to restrict movements during this time. You will be asked to empty your bladder repeatedly and then lie down on the scanner bed with arms extended backwards. The scan takes approximately 30minutes, depending upon the type of scan performed. It is important that you lie still during this process. If you need pain medication please bring it with you. You should plan on being at the PET center for approximately 3 hours. 

Your waiting period may be longer if there is a delay in the supply of the radioactive material or in case of any emergency patient requiring immediate attention. 

As a matter of policy, the preference will be in this order : Sick patients > Children > Others.

Is the procedure painful?

PET CT is essentially painless procedure. You will have a single injection (Intravenous canula placement at the start of the procedure) which is similar to pain from any other injection.

Can i do my routine activities after the scan?

Yes, You can proceed with your normal routine after the scan. 

When can i eat after PET scan?

After your doctor and technologist confirms that the scan is over, you can have your routine food. 

I already have an appointment. Can i cancel it the day before ? 

PET-CT scan uses radioactive material which decays as time progresses. Hence, refund of the deposit made for the medicine (FDG) is not possible under any circumstance. No request for cancellation will be entertained if the same is made less than 48 hours of the time of appointment.

General information about PET-CT scan

What is PET?

PET is the abbreviation for Positron emission tomography. PET scan involves injection of a positron emitting radio-isotope. The emitting positron after undergoing annihilation emit two gamma rays in opposite direction. This is imaged using PET scanner.

What is PET-CT scan?

When a PET scan is combined with a CT scan it is called PET-CT scan. Almost all the PET scanners are fitted with latest CT scan. So, almost all the PET scanners are actually PET-CT scanners.

What is FDG?

FDG is abbreviation for Fluoro-deoxyglucose. FDG is a glucose analogue (meaning it behaves like glucose). The difference between glucose and FDG is that FDG does not undergo glucose metabolism and is hence trapped intra-cellularly. Cancer cells use excess glucose for their metabolism. So when FDG is injected, cancer cells take up more FDG. FDG also gets trapped intra-cellularly and hence they are seen as hot spots on PET scan.

Where is PET scanning used?

PET scanning was initially used in the evaluation of neurological conditions. FDG was found to accumulate in cancers. This finding revolutionized oncology imaging. PET scan was initially used in lymphoma and lung cancer. But now, FDG-PET scan has been shown to be useful in almost all the fast growing cancers. Most of the cancers like lymphoma, breast cancer, lung cancer, esophageal cancer, head and neck cancer, colo-rectal cancer, cholangiocarcinoma, gynecological malignancies, testicular cancer show intense affinity for FDG. FDG PET scan also has been found to change the management of more than 15% to upto 40% of these cancer patients.

How is FDG produced?

FDG is positron emitting radiopharmaceutical. It is produced in a medical cyclotron. Medical cyclotron is an instrument to accelerate particle and produce radio-isotopes. For the synthesis of FDG, radioactive fluoride is produced in medical cyclotron. Fluoride is then subjected to chemical reaction with mannanose triflate to produce FDG.

Are there any medical cyclotrons in kerala?

No. At present there is no medical cyclotron in kerala. FDG is purchased from vendors in chennai, banglore or bombay. In near future, medical cyclotron may come up in kerala or kerala-tamilnadu border.

Why do we need PET scan when there is already CT scan?

PET-CT scan is functional-anatomical fusion imaging technique. PET scan specifically deals with the functional changes in an organ, long before morphological changes occur.
For example, when a cancer arises, initially there wont be much change in the morphology or structure of the organ. When the cancer grows to a particular size, it may be visualised using CT scan. However, PET scan detects cancer even before structural changes occur. Hence, very early detection of cancer is possible with PET scan. Of all the available imaging modalities, PET scan detects the cancer at the earliest. Early detection of cancer leads to curative treatment, even before spread to other sites of the body.

After treatment such as radiation and surgery, fibrosis occurs. CT scan is unable to differentiate between fibrosis and recurrent cancer. PET scan owing to its functional nature can easily differentiate between fibrosis and recurrent tumor.

Inclusion of PET scan leads to significant change in the patient management (upto 40% of the patients).

Why is PET-CT scan costly?

PET-CT scan uses FDG as the medicine. Currently, the cost of FDG is high. Secondly, PET-CT scan involves scanning the entire body (Head to mid-thigh). Considering that the scan involves the whole body, the cost is acceptable.

Is there any risk of allergy while undergoing PET scan?

No. There is no known allergic reaction to FDG. However, CT part of the PET scan utilises intravenous contrast. If you are allergic to intravenous contrast, please inform the staff. Scan will be done without using intravenous contrast and hence allergic reaction can be avoided.