Positron Emission Tomography (PET)

         Positron emission tomography (PET) is a type of nuclear medicine procedure that measure metabolic activity of the cells of body tissues. PET is actually a combination of nuclear medicine and biochemical analysis. Used mostly in patients with brain or heart conditions and cancer, PET helps to visualize the biochemical changes taking place in the body, such as the metabolism (the process by which cells change food into energy after food is digested and absorbed into the blood) of the heart muscle.

      Since PET is a type of nuclear medicine procedure, this means that a tiny amount of a radioactive substance, called a radiopharmaceutical (radionuclide or radioactive tracer) is used during the procedure to assist in the examination of the tissue under study. Specifically, PET studies evaluate the metabolism of a particular organ or tissue, so that information about the physiology (functionality) and anatomy (structure) of the organ or tissue is evaluated, as well as its biochemical properties. Thus, PET may detect biochemical changes in an organ or tissue that can identify the onset of a disease process before anatomical changes related to the disease can be seen with other imaging process such as computed tomography (CT) or magnetic resonance imaging (MRI).

      PET is distinct from other nuclear medicine tests in that it measure metabolism inside human tissues, whereas other tests measure the concentration of radioactive material in a particular area of a body tissue to assess that tissue's function.

     Cardiologists, neurologists, and neurosurgeons (doctors who specialize in treating and operating on disorders of the brain and neurological system) are the medical professionals most likely to employ PET (doctors specializing in the treatment of the heart). However, as PET technology develops further, this process is starting to be applied more frequently in other fields.

       In order to provide more conclusive information on malignant (cancerous) tumors and other lesions, PET may also be utilized in conjunction with other diagnostic procedures like computed tomography (CT) or magnetic resonance imaging (MRI). The PET/CT scanner, a more recent innovation, combines the PET and CT technologies. When used to diagnose and treat lung cancer as well as to assess epilepsy, Alzheimer's disease, and coronary artery disease, PET/CT has considerable promise.

      PET is most frequently utilized by oncologists (specialists having some expertise in malignant growth treatment), nervous system specialists and neurosurgeons (specialists work in treatment and medical procedure of the cerebrum and sensory system), and cardiologists (specialists spend significant time in the therapy of the heart). In any case, as advances in PET innovations proceed, this method is starting to be utilized all the more broadly in different regions.

      PET may likewise be utilized related to other indicative tests, like figured tomography (CT) or attractive reverberation imaging (X-ray) to give more conclusive data about harmful (malignant) growths and different sores. More up to date innovation consolidates PET and CT into one scanner, known as PET/CT. PET/CT shows specific commitment in the conclusion and therapy of cellular breakdown in the lungs, assessing epilepsy, Alzheimer's illness and coronary conduit sickness.

      Initially, PET methods were acted in devoted PET places, in light of the fact that the gear to make the radiopharmaceuticals, including a cyclotron and a radiochemistry lab, must be accessible, notwithstanding the PET scanner. Presently, the radiopharmaceuticals are delivered in numerous areas and are shipped off PET places, with the goal that main the scanner is expected to play out a PET sweep.

      Further expanding the accessibility of PET imaging is an innovation called gamma camera frameworks (gadgets used to filter patients who have been infused with limited quantities of radionuclides and as of now being used with other atomic medication methods). These frameworks have been adjusted for use in PET sweep methods. The gamma camera framework can finish a sweep all the more rapidly, and at less expense, than a customary PET output.

     WORKING PRINCIPLE

                PET detects photons—subatomic particles—emitted by a radionuclide in the organ or tissue being studied using a scanning device, a machine having a large hole in the middle.

         The radioactive atoms that are attached to chemical compounds that are naturally utilized by the specific organ or tissue throughout its metabolic process result in the radionuclides that are employed in PET scans. For instance, because the brain utilizes glucose for metabolism, a radioactive atom is used to turn blood sugar into the radionuclide fluorodeoxyglucose (FDG) during brain PET scans. There is a lot of FDG utilized in PET scanning.

        Depending on the scan's objective, other chemicals could be employed. A radioactive form of oxygen, carbon, nitrogen, or gallium may be used as the radionuclide if the blood flow and perfusion of a particular organ or tissue are of interest.

        An intravenous (IV) line is used to inject the radionuclide into a vein. Then, the bodily portion being studied is progressively passed over by the PET scanner. The radionuclide's breakdown releases particles. When positrons clash with electrons close to the decay event, gamma rays known as annihilation photons are produced. The annihilation photons are then detected by the scanner when they coincidentally arrive at the detectors 180 degrees apart.

     These gamma rays are examined by a computer, which then utilizes the data to build an imaging map of the organ or tissue under investigation.