PET or positron emission tomography scan is a very helpful imaging diagnostic modality that offers great insight into the metabolic or biochemical function of the tissues and organs of a human body. A PET scan shows both...
Introduction
PET or positron emission tomography scan is a very helpful imaging diagnostic modality that offers great insight into the metabolic or biochemical function of the tissues and organs of a human body. A PET scan shows both typical and atypical metabolic activity by using a radioactive drug known as a tracer.
It is very useful in detecting the atypical metabolism of the tracer in diseases much earlier compared to other imaging tests, such as CT (computerized tomography) scans and MRI (magnetic resonance imaging).
The tracer is usually injected into a patient’s vein within the hand or arm. After that, the tracer collects into areas of the patient’s body that show higher levels of metabolic or biochemical activity. So, this is an indication and it often spots the exact location of the disease. The PET images are generally clubbed with CT or MRI and that is why they are called PET-CT or PET-MRI scans.
Here we will delve into the details of a PET-CT scan:
Why do doctors advise PET CT scans?
A PET CT scan is very helpful and an effective diagnostic modality for the medical fraternity. It is a great technique to detect a variety of conditions such as cancer, heart disease, and brain disorders.
The doctors use these findings and interpret the information to diagnose, monitor or treat a patient’s condition.
Cancer
In PET scans cancer cells are revealed as bright spots as they are characterized by a higher metabolic rate than typical cells. So, PET scans may be helpful in:
- Diagnosing cancer.
- To ascertain if there is spreading of the cancer.
- To find out if treatment for the cancer is working.
- To detect a cancer recurrence.
It is also worthwhile to mention that PET scans need to be interpreted very carefully because noncancerous conditions also appear like cancer. Moreover, some cancers may not even come up on PET scans. It is with PET CT scans, many types of solid tumors are detectable, including:
- Cervical
- Brain
- Breast
- Colorectal
- Head and neck
- Esophageal
- Lymphatic system
- Lung
- Prostate
- Pancreatic
- Thyroid
- Skin
- Heart disease, etc.
PET scans can expose areas that have decreased blood flow in the heart. This information is paramount in helping a patient and the doctor to decide, the type of subsequent intervention. It can provide great information and help in taking decisions whether a patient might benefit from coronary artery bypass surgery or needs angioplasty, a procedure in which clogged heart arteries are opened.
Brain disorders
PET scans are equally helpful in diagnosing certain brain disorders, including tumors, Alzheimer's disease, and seizures.
What to do before a PET scan?
It is important to be transparent for the patient and he or she should divulge everything to the consulting doctor. The patient should talk frankly with the physician and inform them about everything including the following:
- If the patient had any bad allergic reaction earlier.
- If the patient has been sick in the recent past or has another medical issue, such as diabetes.
- If they have been taking any medicines, herbal supplements, or vitamins.
- If one is pregnant or may doubt being pregnant.
- If one is breastfeeding.
- If a patient has claustrophobia and is scared of enclosed spaces.
After this elaborate discussion, the doctor usually gives detailed instructions about preparing for the PET scan. As a thumb rule, one should avoid doing strenuous exercise for a couple of days before undergoing the scan and also avoid eating four hours before the scan.
So, a patient can get all the information about what to eat before a PET scan by discussing it with the doctor.
What to expect with a PET scan?
The PET-CT scanner uses a large machine, which appears like a giant doughnut standing tall, and they are akin to CT or MRI scanners.
The whole process of a PET CT scan is completed in about two hours and it does not call for in-patient requirements. A patient doesn’t have to stay overnight in a hospital for the PET-CT scan.
On arrival at the hospital or facility, a patient may be basked certain things like changing into a gown provided by the hospital. So, if you wanted to know what to wear for a PET scan, it will always be loose clothes, mostly provided by the facility.
The patient will be asked to evacuate the bladder. After that, a technician, who is part of the evaluation team, will inject the tracer into a vein of the patient in the arm or hand. The patient may feel a slight cold sensation moving up the arm. Then, the patient will have to lie down silently in a reclining chair for 30 minutes to an hour so that the tracer is absorbed in the body.
PET CT scan procedure
When all the preliminary formalities and preparations are done satisfactorily, the patient is ready to undergo the PET CT scan. The patient has to lie down on a narrow, padded examination table that goes into the scanner, which represents the shape of a doughnut hole. The patient should remain motionless, which will ensure that the images come out crystal clear and not blurry. It takes about half an hour for the complete PET-CT scan while it is 45 minutes for a PET-MRI scan. The patient should be aware beforehand that the PET CT scan machine will make buzzing and clicking sounds.
This test is painless, but if the patient has claustrophobia, he or she may feel slightly uneasy while inside the scanner. This is nothing to worry about. The patient should disclose being wary of enclosed spaces so that the doctor could give an anxiety medicine to calm the nerves and induce relaxation. However, it is important to know that a patient should always take any medication prescribed by the doctor only. The technicians may not be eligible to prescribe any medicines.
What to do after a PET CT scan?
Once the PET CT scan is over the patient is free to carry on with the daily chores as usual. It is only after the doctor tells otherwise there is nothing special a patient has to do after a PET CT scan. The patient should also drink plenty of water or fluids so that the tracer is flushed out from the body.
Interpretations
After the scan is over, a radiologist will take over the proceedings. A radiologist is a specialist trained who interprets the scan images. He or she will then report the findings to the concerned or consulting doctor of the patient.
The radiologist is likely to make a comparison of the patient’s PET images with images from other tests he or she may have undergone recently, including an MRI or CT. The radiologist may also combine the PET images to provide more details about the patient’s current condition. Once the interpretation is complete, the final report is sent to the doctor, who initiates the next intervention steps accordingly.
Conclusion
Hence, we have seen that a PET CT scan is an invaluable imaging tool to diagnose a host of critical illnesses and help the doctor to devise effective treatment solutions for the patient. A patient should strictly adhere to the instructions provided by the doctor to ensure accurate and detailed findings for a better treatment.
FAQs
What should one not do before a PET scan?
One should avoid doing exercise 24 hours before the PET CT scan. The patient should follow a special diet for 12 to 24 hours suggested by the doctor before the scan. One should also refrain from eating and drinking anything, except water, for six hours before the scan.
What preparation is needed for a PET scan?
One should not eat or drink anything, barring water, for six hours before the PET CT scan. However, the patient should drink as much water as possible because it would be helpful, until arrival. It is also allowed to take routine medicines but it should be consulted beforehand with the doctor regarding this.
What should one not do after a PET scan?
After a PET scan, a patient may be advised not to go near a pregnant woman and stay in close contact for a longer time. One should also avoid going closer to babies or young children for a few hours after a PET scan. This is because the patient might still be radioactive during this time.
What is the disadvantage of a PET scan?
There may be a few disadvantages of a PET scan, though it is very rare. PET scans might provide false results at times, especially when the chemical balances within the body are abnormal. It is especially true of diabetic patients or patients who had consumed food within a few hours before the scan. These scenarios can adversely impact the results due to the altered blood sugar or blood insulin levels in the patient.
