Significance of PET – Positron Emission Tomography in Clinical Trials
PET also known as Positron Emission Tomography is a medical imaging procedure or technique widely used in clinical research. It is a type of nuclear medicine imaging. Nuclear imaging is an area of medical imaging in which the severity of diseases or treating the condition is determined with the use of radioactive material. Nuclear medicine procedures are non invasive with intravenous injection as an exception which is usually painless.
PET scanners are used to produce 3-dimensional image of functional process within the human body. It helps to reveal the functioning of tissues and organs. The scanner detects pairs of gamma radiation that are emitted by the radioactive tracer given to the patient.
The images are then reconstructed by computer analysis. The radioactive tracer might be injected in the body, swallowed or inhaled as a gas depending on the area or the organ in the body to be examined. Eventually this radioactive material got accumulated in the body organ to be scanned. Radioactive material generally accumulated more in the area which has high level of chemical activity.
In many clinical or imaging trials PET images might be superimposed with CT – Computed Tomography to produce special views, this practice known as image fusion. In this case, positron emission tomography will produce the functional aspect of the body (for example blood flow, use of oxygen, metabolism of glucose etc.) while the computed tomography will produce the structural aspect of the body organs (for example lungs, liver, stomach, pelvis, and many more). Combined use of positron emission tomography and computed tomography is immensely useful as the fused images produced by this technique can predict very accurately the anatomic location of any abnormal metabolic activity in the body.
To undergo a PET scan, patients have to fast for 4 to 6 hours prior to scanning procedures, but they have to consume plenty of water. Then the radiotracer would be injected into the arm or swallowed or inhaled which may take about 30 – 90 minutes to reach the target cells. For this duration the patient has to fast. After this the patient has to be scanned. Once the necessary part of the body is scanned the patient is again asked to consume plenty of water so as to flush the radioactive tracers out of the body more quickly. It might take about 3 to 4 hours for the radioactive tracers to completely wash out from the body system. It’s not recommended for pregnant women to undergo PET scanning as there is a risk for the baby.
PET – Positron Emission Tomography is used in the imaging part of a clinical trial in studies on Hodgkin’s or non-Hodgkin's lymphoma, colorectal, lung, breast cancer and melanoma. It is also used in pre-clinical studies in animals in order to facilitate repeat investigation in the same subject, thus helping in oncology research studies leading to an increase in statistical quality of the data and substantially decreasing the number of animals required for any given study. Thus using PET scanner for clinical trials is a valuable technique.
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