Differentiating Positron Emission Tomography- Computed Tomography (PET/CT) and a Magnetic Resonance Imaging (MRI)
- As per a study published in the Journal of the American Medical Association (JAMA), a whole body PET/CT is more useful in determining the extent of tumor as compared to a whole body MRI
- An MRI produces an external magnetic field which allows the viewing of the internal organs in a three dimensional format. On the other hand, a PET/CT machine combines imaging with nuclear medicine which allows “functional imaging”. Hence the PET/CT is capable of depicting spatial distribution of metabolic activities in the body, by simply correlating information from the two different devices. A software technology allows the two dimensional images (of the PET scan) and three dimensional images (of the CT scan) to be superimposed and help to reconstruct the image of the internal organ.
- Though MRI and PET/CT both are used for a whole body tumor staging in a single session, Magnetic Resonance Imaging (MRI), mainly focuses on morphological or structural characteristics of the tissue, on the other hand Positron Emission Tomography when used in conjunction with a CT scan provides metabolic functional information about the tissue cells
- The functional metabolic information will help in appropriate staging of different malignancies. This gives a PET/CT an edge over the MRI.
Preparing for the Positron Emission Tomography- Computed Tomography Examination:
There are no special considerations for the preparation, for the scan tests; however certain guidelines are to be followed,
- The patient is expected to share a detailed medical history with the technologist and the presiding physician. This will keep them informed about the patient’s condition and also guide them in terms of what to specifically look for in the scans
- An intravenous contrast material will be injected during the scan and hence patients with previous history of any form of allergic reaction (to sea food, iodine, etc) should inform the technologist before hand. In such cases, they would use an alternate contrast material
- For breast feeding mothers, it is recommended that mothers extract breast milk prior to the procedure and store it to feed their babies, till the contrast material is completed excreted from the body ( which is approximately 12 hours after the tests)
- Metal objects, jewellery, dentures, eye glasses, etc are not allowed inside the scan room and should not be carried to the scanning centre.
- The patient is asked to refrain from ingesting anything after midnight of the day prior to when the surgery is scheduled (i.e. for about 12 hours prior to the scan). Except for diabetic patients who are made special recommendations to avoid hypoglycemic attacks
Positron Emission Tomography- Computed Tomography:
The principal of how a PET scan operates can be explained as follows,
- A typical X ray, releases beams that pass through the body via an external source, which create an image of the internal organs on a film
- On the other hand, for a PET scan, a radioactive substance called a radiotracer or radiopharmaceutical is injected in the patient’s body. This material, then collects in the tissue or organ which has to be examined, are releases gamma rays (from inside the body) which are detected by special a camera called “Gamma camera”. This gives a more comprehensive understanding of the internal structure.
- Also the radiotracer or radiopharmaceutical accumulates in the organ depending upon the metabolic or chemical activity. Hence, the radioactive material is found in a greater concentration in areas where the metabolic or chemical activity is high and in lesser concentration in areas where the metabolic or chemical activity is low. This allows the physician to understand the physiological process within the body in addition to understanding the anatomy and structure.
Positron Emission Tomography- Computed Tomography: The procedure
- The procedure doesn’t require hospitalization, and is normally performed as an out patient procedure.
- The patient is appropriately positioned on the examination table of the imaging device.
- A radiotracer or radiopharmaceutical is injected intravenously. Alternatively, the patient may be asked to swallow or inhale the radiotracer depending upon the organ that is to be examined
- After the ingestion or injection of the radiotracer, the patient is requested to rest without moving or talking for approximately about an hour. During this time the radiotracer travels through the body and is gets accumulated into the tissue or the organ that is to be studied.
- Subsequently, the patient is given contrast material to drink which localize and accumulates in intestinal tissue and facilitate the radiologist in interpreting the findings of the examination.
- Now, the patient is moved to the scanning room and the process of imaging begins. The patient is asked to not to move during the imaging process.
- First, the CT scan examination is done, and then the PET scanning examination is done. CT scan examination takes hardly a couple of minutes, while PET scan examination takes approximately half an hour.
- On completion of the examination, the technologist would review the images and check if there is a need to take additional images. On some occasions, additional images may be required. Please don’t panic in such situation, as the additional images help the radiologist to gain greater clarity over the examination and visualize certain areas more clearly.
Limitation of the Positron Emission Tomography- Computed Tomography test
- The procedure requires the radiotracer to accumulate in a particular organ or body part which is to be examined. This could take hours or even days, though newer technologies have hastened the process. Further the imaging studies could take a few hours.
- Since PET scan primarily focuses on studying the metabolic functions in the organ tissues, chemical imbalances within the body may give false test results. This is most commonly observed in patients having diabetes.
- The radioactive substance used has a very short half life and decays very fast. Therefore, in any case, if there is any delay, the procedure needs to be invariably rescheduled
Precautions to be taken after a Positron Emission Tomography- Computed Tomography Test
- The radiotracer injected has a very short half life and will decay very soon. It is excreted within the first few hours after the examination. Hence the patient is requested to drink lots of water to hasten the excretion of the radiotracer
- Since the radiotracer is excreted through urine, the patient is instructed to follow special precautions like flushing the toilet two times after using it and washing the hands thoroughly to avoid accumulation of the radioactive substance.
- Occasionally, patients are known to suffer from allergic reactions to the radiotracer or the contrast material which is used. The patients are instructed to inform the doctor immediately in such a situation, to help take immediate remedial action
- Site of intravenous injection of the radiotracer may cause slight pain and irritation for a few hours after the examination.
Positron Emission Tomography- Computed Tomography Test in India:
India is one of the fastest growing nations in the world, with its healthcare system registering a growth of over 15% annually. This exponential growth in all sectors has propelled the development and has put India on the map of the best medical tourism destinations across the world.
Positron Emission Tomography- Computed Tomography Test in South Korea:
With superior quality of medical and healthcare infrastructure, and highly trained and skilled medical teams, South Korea has the best healthcare facilities. These facilities house the very best and ultra modern equipments that have contributed significantly in the improvement of the overall quality and effectiveness of medical care services.
Positron Emission Tomography- Computed Tomography Test in Mexico:
Mexico has several JCI accredited hospitals (adhering to international infrastructural norms for hospitals), which are specially designed to cater to foreign medical tourists especially from the neighboring United States of America. Mexico gives the advantage of cost and proximity to American Medical Tourists.
Positron Emission Tomography- Computed Tomography Test in Jordan:
Jordan is one of the fastest growing medical tourism destinations in the world. The country has registered an astonishing increase in the number of medical tourists visiting annually. Jordan predominately caters to the European nations, but has also gained strong reputation among several Americans medical tourists.
Positron Emission Tomography- Computed Tomography Test in Turkey:
Turkey has evolved as a centre of international medical care, as it caters to most of the Middle Eastern countries. Turkey’s biggest strengths are its highly trained and qualified manpower and low cost services. Its proximity to the Middle East has helped it grow as a medical tourism destination.
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Medical Tourism Corporation facilitates whole body positron emission and computed tomography (PET/CT) in Europe (Turkey) and other overseas world-class oncology treatment destinations.